amx programing course

8/2/2019 AMX Programing Course

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Table of Contents


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Welcome....................................................................................................................1

Course objectives....................................................................................................1

Introduction...............................................................................................................2

The AMX Language Course.............................................................. 2What is NetLinx?.............................................................................. 2

Unit 1: Language Basics..........................................................................................3

Chapter 1 - Simply the Basics.................................................................................3

Introduction.................................................................................... 3

Format of the language.................................................................... 3

Statements and Compound Statements.............................................. 4

Comments Within the Program.......................................................... 5

Identifiers......................................................................................... 6

Reserved Words.................................................................................. 6

Special Characters and Operators.........................................................6

Chapter 2 - The Definition Sections........................................................................7

Starting a New Program..................................................................... 7

Defining Devices................................................................................ 7

Defining Constants............................................................................... 9

Defining Variables................................................................................. 10

Startup Code......................................................................................... 11

DEFINE_EVENT and Mainlinein NetLinx.................................................... 11

Chapter 3 - Using Input and Output......................................................................13

Controlling Something Over There................................................. 13

The device Channel Concept........................................................ 13

All About the channel................................................................ 13

Changing the State of a channel................................................... 15

Putting input and Output Together.................................................. 18

Chapter 4 - Channel Characteristics.....................................................................19

The Parts of an Output Channel....................................................... 19

Mutually Exclusive............................................................................ 19

Putting it All to Work........................................................................... 21

Programming Feedback....................................................................... 23

Grouping Feedback Statements............................................................... 24Unit 2: Conditionals and Waits........................................................................................25

Chapter 5 Conditional Expressions................................................................... 25

Introduction..................................................................................................................... 25


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Conditional Expressions.................................................................................................. 33

The IF Statement............................................................................................................ 33

The IF...ELSE Set of Statements.................................................................................... 33

Repeating IF...ELSE Set of Statements.......................................................................... 34Nesting............................................................................................................................ 34

The SELECT...ACTIVE Statement.................................................................................. 35

Trying it Out..................................................................................................................... 36

Conditional Operators..................................................................................................... 39

Chapter 6 The Wait Keywords............................................................................ 41

Controlling Time Within the AMX System....................................................................... 41

The WAIT List................................................................................................................. 41

Multiple Wait Statements................................................................................................ 43

Special Uses of Wait....................................................................................................... 45

Naming Wait Statements................................................................................................ 45

Canceling, Pausing, and Restarting Wait Statements.................................................... 46

The WAIT_UNTIL Keyword............................................................................................. 46

Misusing WAIT_UNTIL.................................................................................................... 47

Naming and Removing WAIT_UNTIL Statements.......................................................... 47

Unit 3: Levels.......................................................................................................... 49

Chapter 7 Creating and Using Levels................................................................ 49

Introduction..................................................................................................................... 49

What is a Level?.............................................................................................................. 49

Creating Levels............................................................................................................... 49

Reading Levels............................................................................................................... 52

Making a Preset.............................................................................................................. 52

Using Bar Graphs............................................................................................................ 53

Connecting Levels........................................................................................................... 53

Unit 4: Arrays and Sending and Receiving Strings............................................ 55

Chapter 8 Arrays and Strings............................................................................. 55

Introduction..................................................................................................................... 55

Defining Arrays................................................................................................................ 55

Accessing and Storing Array Values............................................................................... 56

Data Types...................................................................................................................... 59

Strings............................................................................................................................. 60

The String Expression..................................................................................................... 61String Elements............................................................................................................... 61


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String Lengths................................................................................................................. 62

Sending Strings and Arrays............................................................................................. 63

ASCII Codes.................................................................................................................... 6

4Integer Arrays.................................................................................................................. 64Chapter 9 Working with Arrays..........................................................................67

Grouping Data................................................................................................................. 67

Conversion keywords...................................................................................................... 67

Array Manipulation Keywords.......................................................................................... 69

UPPERCASE vs. lowercase........................................................................................... 71

Setting Uppercase and Lowercase................................................................................. 71

Chapter 10 Receiving Strings.............................................................................73

Listening to the Outside World........................................................................................ 73

Receiving Strings............................................................................................................ 73

Storing characters........................................................................................................... 73

Retrieving Characters...................................................................................................... 74

Appendix: Troubleshooting...................................................................................75

ESCAPE.......................................................................................................................... 75

Appendix: Standard IR Function Order................................................................77

Appendix: ASCII Code Chart.................................................................................79

Welcome


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Welcome to Introduction to AMX Programming. This self-paced course is for new

Programmers,

Installers who want to learn AMX programming, and Technical Support Personnel and

teaches the

basic techniques for programming an AMX Control System. A person completing this self-

paced

course will be able to understand a basic AMX program and have the basis for successful

completion of subsequent AMX programming classes.

This manual is designed to be both a reference for on the job and a tool for self-paced

training.

White space is available on every page for taking notes. There is references to programming

code

that accompanies this manual. The companion code files are in the zip file that also contains

this

manual. Good luck!

Course Objectives

Upon completion of this self-paced course you will be able to:

! Understand the basic principles of AMX Programming

! Understand the core components of AMX devices

! Understand how to program channels, levels, and strings related to each device

! Understand Buffer/ String Processing functions! Utilize the basic techniques to debug programming errors in a NetLinx program

IntroductionThe AMX Language Course

This self-paced course takes the approach of teaching the common elements of AMX

Programming

languages while developing real world AMX Control System programs. You will start with the

basic commands and simple control scenarios, and progress on to more complex

programming as

you discover new programming functions and techniques. With the exception of additional

keywords and objects in the NetLinx programming language, there are very few differences in

many programs.

What is NetLinx?

In the continuing evolutionary process of control systems AMX introduced the NetLinx Control

System. NetLinx is the most advanced control system developed in that process. The NetLinxsystem can not only control devices connected directly to its control ports and local control


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networks but can control and communicate seamlessly to other control systems and devices

on

Ethernet networks and the Internet. The NetLinx hardware takes the experience gained from

more

than a decade of Axcess system installations to make a more powerful control system.

To enable this giant step in system development the Axcess programming language, the

basis of the

Axcess control system, was enhanced and supplemented to provide the programming power

for

NetLinx.

The NetLinx system is an Event driven system. As inputs come into the system that input is

compared against an Event table. This Event table can keep track of things such as button

presses

on a panel, channels turning on and off, and responses received from connected devices.

You will

see many Events in examples throughout the tutorial, and this concept will be discussed later

in

Chapter 2 inDEFINE_EVENT and Mainline in NetLinx on page 11 and in greater detail in

AMX

Programmer I.

Unit 1: Language BasicsChapter 1 - Simply the BasicsIntroduction

This unit will help you start writing AMX programs. By the end of this unit you should be

familiar

with several concepts:

! Basic ground rules for writing AMX programs

! The device channel concept

! The different sections that make up an AMX program

! How NetLinx executes a program

! Basic input and output functions

! Simple feedback.

As you progress through the chapters you will develop a simple Axcess program containing

these


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basic features, and you will build on this program in later units.

Format of the Language

The AMX languages can be written in a free format, meaning that the source code is

independent of

tabs and carriage returns. Because of this, it is advised to use a consistent method of code

placement in order to make the code more readable. In this manual, an outline format is

used; that

is, each subsection of a section is slightly indented. For example:

BUTTON_EVENT[PANEL,1]

{

PUSH:

{

IF (X = 1)

{

Y = 2

Z = 3

}

}

}

Statements and Compound Statements

During programming, most of the keywords and operators require a complete statement. A

keyword is a word or series of words that signifies the operation for the system to execute.

That

keyword and all its parameters form the statement. For example, the keyword to turn a

channel on is

merely ON. However, the statement to turn on a particular channel (lets say channel 6) is

ON[RELAY_CARD,6]. Statements can also involve mathematical or logical operations when

operators are used. An operator is a character that performs a specific mathematical or

relationalfunction. For example, the operator used to set a variable equal to a value is theequal sign (=). Asexpected, the statement used to set variable X to the number5is X = 5.

You will frequently have to group several different statements together into one compound

statement. The braces { } are used to enclose this type of statement. Compound

statements are

used if several statements are to be executed in a situation where program syntax will allow

just

one. The statements are executed in the sequence in which they are programmed. The

number of


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open braces { and close braces } must be the same in your program. For each open brace

there

should be a corresponding close brace. The compiler will point out this error to you if the

quantities

are different after compiling.

Compound statements give you the ability to group multiple statements together into one unit,

much like grouping sentences together into one paragraph. The most common example of

compound statements occurs with thePUSH keyword. (This keyword is explained in depth

later.)


{

PUSH:

{

ON [RELAY_CARD,5]

X = 5

}

}

In this example, when button 1 onPANEL is pressed, relay 5 onRELAY_CARD is turned on.

Also, the

variableX is assigned the value of 5. The open brace indicates the beginning of the

compoundstatement, and the close brace ends it. If you only needed the relay to be turned on, the

statement

could have been written like this:


{

PUSH:

{

ON [RELAY_CARD,5]

}

}

The code example on the previous page uses two special operators. The chart below list

more detail

about these operators. You will see these used throughout the manual.


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Special OperatorsSpecial OperatorsSpecial operator

operator name Function

{} Braces Combine several statements into a

compound statement

[] Brackets Enclose the device-channel: [device,channel]

Enclose the size or location of a storage

space in an array

Enclose the instance number used with a

SYSTEM_CALL

Enclose a variable to be turned on or off

() Parentheses Enclose the expression after an IF statement

Enclose a mutually exclusive set in the

Define section

Group a mathematical operation

Notes: The uses of braces, brackets, and parentheses cannot be interchanged within the program

Comments Within the Program

AMX programming languages allow you to place helpful comments inside your program. A

comment is a description or remark that is not considered part of the actual program. Once

something is marked as a comment it will not be compiled. It exists only to help people read

the

code. There are three ways to mark something as a comment. The quickest method is to use

a//.

Any text following// will not be compiled. However, the // only designates that the text until the

end of that current line is a comment. The text which would appear on the next line would be

compiled.

//This section will define all the devices used.

DEFINE_DEVICE

VCR = 1:1:0 // ACME VIDEO CASSETTE RECORDER MODEL 1000

CD = 2:1:0// ACME COMPACT DISC PLAYER MODEL 2000

In the above code the first line is just a header. It is preceded by a// so it is not compiled. After

the

devices VCR and CD are addressed there is a comment explaining that line of code. This

method

requires a// to be entered everywhere you want to make a comment. But, there may besituations


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where you want to mark several lines as a comment. You could use// but you would have to

insert

that before each line. To make this easier, NetLinx supports two more methods of making

comments. Both methods work the same way. Any text after(* and before *), or after/*and

before*/ will also not be compiled, even if the text is separated over several lines. See the

following example:

BUTTON_EVENT [T_PANEL,1] // SLIDE PRESET

{

PUSH:

{

(* HERE IS WHERE I WILL PLACE SEVERAL

LINES OF CODE TO BE RUN WHEN BUTTON

NUMBER 1 IS PUSHED ON THE PANEL*)

}

}BUTTON_EVENT [T_PANEL,2]// VHS PRESET

{

PUSH:

{

/* HERE IS WHERE I WILL PLACE SEVERAL

LINES OF CODE TO BE RUN WHEN BUTTON

NUMBER 2 IS PUSHED ON THE PANEL*/

}}

Here the button is labeled using// but the longer comments are marked using a

different(* or*/.You can place any number of comments in your program. However, when the

program is compiled,they will be passed over. Comments have no effect on the actual

operation of the program. It is wiseto use comments. They are especially helpful in a long

program where you can label each part ofthe program for future reference. If changes have to

be made, you can merely look for the label ofthe section you need to edit. As illustrated

above, descriptions ofPUSH statements are very useful.


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Chapter 2 - The Definition SectionsStarting a New Program

Now that the ground rules are laid out, you can start writing your first program! When you

begin anew program, also referred to as a source code file, in NetLinx Studio you are not

given an emptyfile with which to work. Instead, there are several definition headings to signify

what should bedefined in each section. The definition sections that are given to you are the

following:

! D E F I N E_ D E V I C E

! D E F I N E_ C O N S T A NT

! D E F I N E_ T Y P E

! D E F I N E_ V A R I A B LE

! D E F I N E_ L A T C H I NG

! D E F I N E_ M U T U A L LY _ E X C L U S IV E

! D E F I N E_ S T A R T

! D E F I N E_ E V E N T

! D E F I N E_ P R O G R A M

Feel free to delete any of these headings you do not need, and keep those that you do. If you

do not

have any statements under one of these headings, your program will not operate any

differently.

However, you might want to keep the headings there for future reference. Although thedefinition

sections are not used within the main program, they create the materials the main program

needs.

Devices and their channels are given names, channels are given different characteristics, and

variables are formed. Even the immediate startup procedures of the AMX control systems are

within a definition section. If you develop a good understanding of the Define statements, you

will

be able to build an excellent foundation for the main part of your program.

Defining Devices

When you start writing a program, you should first label each device in the system. Each

device

connected to the master must have a unique device number. Card 1 may have device

number 1, and

card 2 may have device number 2. Any time these device numbers are referenced in the

program,

the master checks the corresponding device. However, with a long list of devices connected

tothecontrol networks, these numbers can be difficult for a programmer to


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remember.Assigning actual

names to these devices is much easier.

This is the function of theDEFINE_DEVICE section. It is placed at the beginning of the

program,and it lets you name the devices. Whenever you use this device name in your

program, the compilerwill automatically use the corresponding device number to reference the

device.

VCR CD CASS

Port 9 Port 10 Port 11

FIG. 1NI-3000 is Device 5001

You should start writing your program by first defining the devices in your system. Suppose

youhave a VCR, a CD player, and a cassette deck, and you are controlling them with the first

three IRoutputs on an NI-3000. These IR outputs have device

numbers5001:9:0, 5001:10:0and

5001:11:0. They will have these device numbers because these devices are connected to

ports 9,

10 and 11 on the NI-3000. The program will reference the port that you need to control. You

can

name that port after the device you are going to connect to it. That way the code will make

sense forpeople who read it. The compiler will continue to reference the full port address. The

naming is justfor readability.

Additionally, you also want to control a projection screen, some drapes, and lights. The relays

ofthe NI-3000 will control the screen and drapes and the I/O device of the NI-3000 will control

thelights. A Touch Panel will be the user interface to control all of these devices (in this

instance anNXT-CV15). Here is what yourDEFINE_DEVICE section should look like:


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DEFINE_DEVICE

RELAY= 5001:8:0

(*NI-3000 RELAY OUTPUTS 1-8 *)

VCR

= 5001:9:0

(*NI-3000 IR OUTPUT #1*)

CD

= 5001:10:0(*NI-3000 IR OUTPUT #2*)

CASS

= 5001:11:0(*NI-3000 IR OUTPUT #3*)

LIGHTS = 5001:16:0(*NI-3000 I/O 1-4*)

TP

= 10128:1:0(*NXT-CV15 TOUCH PANEL*)

From this point on, you can reference device 9 with the nameVCR, device 10 with the

nameCD, and

so on. The compiler will understand that when the code references CD it is actually referring

to

5001:10:0 and so everything will work properly.

Notice the Touch Panel is the only device not addressed with5001. That is because theTouch

Panel is an independent device. It is not integrated into the NI-3000 like the other references.

Where as theVCR, CD, CASSand LIGHTS are all controlled by different ports on the NI-3000,

the

Touch Panel is a stand alone device; therefore, the addressing must be different.


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Defining Constants

Constants are identifiers whose values remain unchanged throughout the entire program. The

process of defining them is very similar to defining devices. Assigning a value to an identifier

in

this section locks that value to the identifier for the entire program, making it possible to use

descriptive names instead of just numbers in your program.

In your system, the VCR, CD player, and cassette deck IR devices have channels that

activate thevarious transport functions, such as Play and Stop. As a general rule, Play is

usually channel 1 andStop is channel 2. You could define these channel numbers as

constants in your program to make itmore readable.

DEFINE_CONSTANT

(* TRANSPORT (IR DEVICE) CHANNEL NUMBERS *)

PLAY= 1

STOP= 2

PAUSE = 3

FFWD= 4

REW

= 5

(* THE RELAY DEVICE CHANNEL DEFINITIONS *)SCREEN_UP

=1SCREEN_DOWN = 2SYS_POWER

=3DRAPE_OPEN= 4DRAPE_CLOSE = 5DRAPE_STOP= 6

(* THE LIGHTS DEVICE CHANNEL DEFINITIONS *)

LIGHT_FULL = 1

LIGHT_MED= 2

LIGHT_LOW= 3

LIGHT_OFF= 4

The value of the constantPLAY is 1.STOP has a value of 2. Both of these values cannot be

changed

anywhere in the program. Later in your program when you need to activate the Play function

of the

VCR, you dont have to remember that it is channel 1 of the devicejust use the

constant PLAYand

the system knows to use channel 1. This works in a similar fashion to

theDEFINE_DEVICE section.You don't have to remember the full address of the device just

what you called it. So you can writecode as:


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PULSE [VCR, PLAY]

This used theDEFINE_DEVICE reference and theDEFINE constant reference. Without these

references the code would have to be written as:

PULSE [5001:8:0, 1]

If you have a number of devices with varying functions the device and channel numbers could

be

difficult to remember.DEFINE_DEVICE andDEFINE_CONSTANT can help reduce that

confusion.

By definition, the same constant cannot reference more than one number. This may seem

obvious,but this type of error could work its way into large programs. If you make this mistake,

the compilerwill notify you with a Duplicate symbol error message upon compiling.

Defining VariablesVariables are places to store data that will change as the program is executed. Think of a

variable as

a "storage box;" nearly anything can be placed in here. Variables can hold many types of

data. But,

any single variable can only hold one type of data. Since a variable can hold only one of

several

possible types of data, you must specify what type of data is going into the variable when it is

defined. This 'box' that we are referring to is really an allocation of memory inside theprocessor.

Inside that memory the processor will store a value that can change based on the events that

occur

and how the program is written to handle those events. Depending on what you are trying to

accomplish you may need to store integer values. An integer is an numeric value between 0

and

65535. Then again, you may have a situation which requires you to store character values.

Characters are letters or numbers between 0 and 255. If you do not define the type of data to

be

stored in a variable when it is defined the processor will default the variable type to Integer.

Just as variables can store different types of data, they have different behavior

characteristics.

Some variables retain there values even after the Master processor is powered off and some

do not.Some variables can be used throughout the whole program and some only in certain

subsections.These concepts will be covered in further detail as you get more involved in

programming. For now,you just need to understand that variables can hold different types of

data and that these values canchange while the program is running.


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In your first program you will not be using variables, but keep theDEFINE_VARIABLEheader

because you will be using them in the future. TheDEFINE_MUTUALLY_EXCLUSIVE section

is also

used and explained later.

Startup CodeWhen the AMX Control System is turned on, the program that was last loaded into the system

willbegin to operate. However, you can tell the system to run a series of statements

immediately whenthe system is turned on. These statements are placed under

theDEFINE_START header, and theyare run only once on power-up. They cannot be

executed again until another system power-up. Inyour program, you may want to reset all

three decks toSTOP when the system is powered up. Hereis what

yourDEFINE_STARTsection should look like:

DEFINE_START

PULSE[VCR,STOP]

PULSE[CD,STOP]

PULSE[CASS,STOP]

Remember, code in this section will only run when the Master processor powers up. Typically,

control systems will not be rebooted once they are in place. However, they may lose power,

have

code reloaded, system maintenance, etc. Any of these situations could cause a reboot of the

Masterwhich would allow theDEFINE_START code to run.

DEFINE_EVENT and Mainline in NetLinx

TheDEFINE_EVENT section and theDEFINE_PROGRAM section is where most of the

programmingwill take place. These two sections run concurrently but in different ways to give

the programmeroptions on how the system could work. TheDEFINE_EVENT section allows

extremely fast programfunctions. It makes no difference how large the program is, each

button press or other input is

immediately accomplished. This section is where the majority of our programming is

completed.

TheDEFINE_PROGRAM section (also calledMainline) accesses its programming in a loop

fashion.

The processor continually scans the program looking to keep all of its information current. The

processor starts at the beginning runs through the end of the program in order. Because of

that, if

this section has a very large amount of programming, it could adversely affect the speed or

timing

of the program. Therefore, it is recommended to put most of our programming in the


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DEFINE_EVENTsection.

Because theDEFINE_EVENT section is more efficient, when there is programming for a

particular

button press in both sections, the Master will perform the programming in theDEFINE_EVENT

section and the programming in theDEFINE_PROGRAM section will be bypassed. So, the

DEFINE_PROGRAM section's primary role is maintaining feedback.

You should avoid putting button presses in both sections of code even though the

mainline section will be ignored in this event.

Figure 2,on page 12 illustrates message and mainline processing as it appears in the NetLinx

system. Note that bus servicing is taken care of by a separate process thread (Connection

Manager

& Message Dispatcher) and therefore is not a task that must follow mainline.


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Chapter 3 - Using Input and OutputControlling Something Over There

The basic idea behind remote control is to do something over here to make something

happen overthere. In an AMX system, the something over here is usually some kind of

control panel, such asa wireless remote control panel or a Touch Panel to generate an input.

The something over therecan range from a simple relay to a complex lighting system to

receive the output from the controlsystem.

InDEFINE_EVENT you define what happens when these inputs occur. But how do you get

your

inputs in the program? How do you generate an output? The answer: you use devices and

channels.

The Device-Channel Concept

Everything that is controlled by an AMX control system is considered to be a device on the

system.Each device in that system communicates to the master through control networks.

Netlinx used 4control networks: AXlink, ICSNet, ICSHub and Ethernet. Most devices, such as

a Touch Panel or arelay card, have channels which either accept an input, generate an

output, or both. These inputsand outputs are referred to in the program as a device-channel

pair, which is written like this:

[8:1:0,1]

This device-channel references channel 1 of device 8 on port 1 in system 0. If device names

and

constants are used instead of numbers, the same reference could look like this:

[VCR,PLAY]

Using device names and constants is obviously much more readable. This concept of the

device-

channel is the most basic concept of the entire AMX control system, as it is the most common

way

that the program communicates to the outside world.

All About the Channel

Almost all methods of control using an AMX system require the use of channels on devices.

Everychannel has two aspects: the input function and the output function. When a button is

pressed on acontrol panel, the input function of the button sends an input change to your

program. The inputchange alerts the Master to scan your program for a reference to that

input.

In the NetLinx system a device can have multiple ports, therefore each port must be

addressed. Additionally, since many NetLinx systems can be connected together, up

to 65,535, each device receives the system ID of the connected Master. This

addressing scheme is referred to as the Device:Port:System triplet.


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When there is an input change, the Master passes through the EVENT LIST section once to

see ifthe change is referenced. If so, the Master executes the statement(s) in the program

associated withthe input change. There are 3 keywords used in conjunction with input

changes:

PUSHThePUSH keyword is used to find out if a channel has had an input change from off to on,

suchas when a button is pressed. If the channel has been turned on, the

correspondingPUSH statement isactivated. The operation or operations following thisP

USH statement are only executed once afterthe channel is turned on.

The BUTTON_EVENT/ PUSH keyword requires two parameters: a device number and a

particularchannel enclosed in brackets. A device name or constant can be used in place of a

literal number.For example:

BUTTON_EVENT [10128:1:0,1]

{

PUSH:

{

Y = 2

Z = 3

}

}

IfPANEL is defined as device number10128:1:0, andPLAY is defined as a constant with avalue

of 1, the following is the same:

BUTTON_EVENT [PANEL, PLAY]

{

PUSH:

{

Y = 2

Z = 3

}

}

Following thePUSH statement is the operation to be executed when thePUSH occurs. If more

thanone event must happen, a compound statement must follow thePUSH. (See the earlier

discussion oncompound statements.)


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RELEASE

TheRELEASE keyword is used in the same way as a PUSH, except that the statements

following a

RELEASE statement will be executed if the associated channel is released. For a button on a

touch

panel this happens when you let up on the button.

BUTTON_EVENT [PANEL, PLAY]

{

RELEASE:

{

Y=1

}

}HOLD

AHOLD keyword specifies the actions that should be performed when a button is pressed and

heldfor a minimum length of time indicated by the Time Parameter. (TIME is specified in 0.1

secondincrements). If a repeated action is desired at the same time increment, add the

keywordREPEATwithin the Time Parameter brackets. Remember,REPEAT is optional.

BUTTON_EVENT [PANEL,PLAY]

{

HOLD [TIME PARAMETER,REPEAT]:

{

Z=1

}

}

All three of the keywords can be placed under the sameBUTTON_EVENT.

BUTTON_EVENT[PANEL,PLAY]

{

PUSH:

}RELEASE:{

Y = 1

}HOLD[5]:

{

Z = 1

}

}


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Changing the State of a Channel

So now you can respond to an input change in your program, and you want it to activate a

different

device-channel. The next series of keywords allow you to activate channels based on an input

change. This activation is called an output change, which is a message to the output function

of a

channel. The keywords to do this are:

ON

TO

OFF

PULSE

TOTAL_OFF

MIN_TO

When you use one of these keywords to activate a channel in a device, the device starts the

operation that is associated with the channel. For instance, activating channel 5 on a relay

card

activates the physical relay number 5, whereas channel 5 on an infrared/serial card causes it

to

generate the infrared pattern it has stored at location 5.

Variables can be used as output channels also, but doing so does not actually cause an

outputchange. When a variable is activated as a channel, turning it on gives it a value of 1 (or

makes it

true), and turning it off gives it a value of 0 (or makes it false). Remember that in NetLinx

programming language off = false = 0 and on = true = any number greater than zero.

Following are brief definitions of each of the output change keywords.

ON

TheON keyword simply turns on a channel or variable. If the channel or variable is already on,

its

status will remain unchanged. Here are two different examples:

ON[RELAY_CARD,2]

//THIS TURNS ON CHANNEL 2 OF RELAY_CARD.

ON[TEMP]

//This sets the value of the variable TEMP to 1.

A variable is considered on if it contains a nonzero number; in this case, the value is 1. If a

variable contains the value zero, it is considered off.


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OFF

TheOFF keyword turns a channel or variable off. The channel or variable will remain off if it is

already off. Here are two different examples:

OFF[RELAY_CARD,2]

//THIS TURNS OFF CHANNEL 2 OF RELAY_CARD.

OFF[TEMP]

//This sets the value of the variable TEMP to zero.

TOTAL_OFF

TheTOTAL_OFFkeyword acts in the same manner as OFF, except that it also turns off the

status ofa channel or variable that is in a mutually exclusive set. Mutually exclusive sets are

discussed laterin this unit.

PULSE

ThePULSE keyword turns on a channel or variable for a certain amount of time. Once the

time

elapses, the channel or variable is turned off. As an example, refer back to the discussion on

DEFINE_START. The PULSE keyword was used to activate the three decks Stop function.

The

default duration of this pulse is one half-second, but it can be changed if necessary with the

SET_PULSE_TIME keyword. The pulse time is measured in tenths of seconds. The pulse

time

remains the same value until it is changed within the program. For example:

SET_PULSE_TIME (12)

This sets the current duration of future pulses throughout the whole program to 1.2 seconds.

TO

TheTO keyword is used to activate a channel or variable for as long as the corresponding

device-

channel of itsPUSH statement is activated. When the device-channel referenced by

the PUSH

statement changes fromOFFto ON, the TO starts activating the device-channel or variable inthe

brackets following it. When the device-channel of itsPU SH is released, theTO statement

stops

activating its device-channel or variable. The TO keyword has several conditions:


24/93

! It must be used only below aPUSH statement.

! It cannot be used with theWAIT keyword. (This will be explained later.)

! It cannot be placed within theDEFINE_START section.

The channel or variable will act under the rules set byDEFINE_MUTUALLY_EXCLUSIVE.

You will

learn what that definition section means later when you add more to your program.

BUTTON_EVENT [PANEL, 6]

{PUSH:

{

TO [RELAY, 6]// THE RELAY WILL TURN ON WHILE BUTTON HELD

TO [TEMP]// THE VARIABLE WILL BE TRUE WHILE BUTTON HELD

}

}

MIN_TO

TheMIN_TO keyword is used to activate a channel or variable for at least a minimum amount

of

time or as long as the corresponding device-channel of itsPUSH statement is activated. When

the

device-channel referenced by thePUSH statement changes from OFFto ON,

the MIN_TOstarts

activating the device-channel or variable in the brackets following it. When the device-channel

of

itsPUSH is released, the MIN_TO statement stops activating its device-channel or variable if

the

button was held for at least the minimum amount of time as set by the pulse time.

TheMIN_TO

keyword has the same conditions as theTOkey wo rd :


25/93

! It must be used only below a PUSH statement.

! It cannot be used with the WAIT keyword.

! It cannot be placed within the DEFINE_START section.

Direct Assignment

There is another method of generating an output change, but it does not involve the use of

any

keywords. Any reference to a device-channel that does not have the

keywordsPUSHorRELEASEpreceding it is a reference to the output side of the channel. Thus assigning a value directly to

a

device-channel changes the output of the channel. For example:

[PANEL,1] = 1

This statement will send an output change to channel 1 of devicePANEL, telling the channel

to turn

on since the master interprets any non-zero number as on. Putting this statement in

mainline will

make the channel be forever on. Using direct assignment is only appropriate in feedback

statements. In most other situations, the keywordsON, OFF, and TO are more appropriate.


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Putting Input and Output Together

Combining input and output changes into one statement is the basis of most AMX Control

Systemprogramming. Now that you have these tools, you can write the code that can actually

accomplishthis. On your Touch Panel, you will have button numbers 1 through 5 activate the

five transportfunctions of the VCR: Play, Stop, Pause, Fast Forward, and Rewind. Here is

your first section ofprogram code:

BUTTON_EVENT[TP,1]

{

PUSH:

{

PULSE[VCR,PLAY]

}}BUTTON_EVENT[TP,2]

{

PUSH:

{

PULSE[VCR,STOP]


{

PUSH:

{

PULSE[VCR,PAUSE]}

In this code, there are actually five separate but similar statements. Examine the first to see

how it

all fits together. First there is aBUTTON_EVENT, meaning we are programming in the

DEFINE_EVENT section. This is followed by a device-channel reference, in this case [TP,1].

Next,

an action takes place on thePUSH. This tells the control system, "If channel 1 on

the 10128:1:0

device receives an input change fromOFFto ON (i.e. someone pushed a button) execute the

statement that follows." If such an input change occurs, the correspondingPULSEstatement

executes. ThePULSE statement tells the control system, When channel 1 on

device10128:1:0 is

activated,PULSEd ev i c e 5001:8:0, channel 1. You may be wondering where the numbers

came

from, since thePUSH andPULSE statements have the wordsTP,VCR, andPLAY.

Remember,TP and


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VCR are identifiers for devices 10128:1:0and 5001:8:0 respectively and PLAY is a constant

with

a value of 1.

Duplicate the above section for the CD player and the cassette deck,

replacingVCR withCD and

CASS where needed. Also be sure to use different channel numbers for

the PUSH statements, or one

activation of channel 1 could make all three decks play at the same time. Touch Panel

BUTTON_EVENT numbers for the CD player are 9-13, for the Cassette deck use channels

17-21.

Now that you have the transport functions of your decks programmed, you can add the rest of

thefunctions on your panel to the program. But before you do that, you need to learn about

the otherdefinition sections: those that define the characteristics of a channel.


28/93

Chapter 4 - Channel CharacteristicsThe Parts of an Output Channel

An output channel actually has two parts, the physical part and the status part (simply

referred to as

status). The physical part is the device-dependent physical control, such as a relay on a

relay

card, a button light (lamp) on a Touch Panel, or an infrared pattern in an infrared card. The

physical part of a channel can be only one of two things, on or off. The status is what records

the

state of the physical part and reports it to the Master. In most applications, these two parts act

exactly the same; when one is on, so is the other.

However, you can change the way the status (or reporting) part of an output channel

behaves. In this

chapter, you will be shown how to change the status behavior, which in turn changes the way

a

channel reacts when it is activated by the output change keywords.

All channels are momentary by default.1 When a momentary channel is activated with aTO

keyword, it activates its output and status only as long as the button which activated

theTOkey wo r d

is pressed. For example, the Focus channel for a certain slide projector is momentary. When

the

corresponding Focus button is pressed, the slide projector will focus. The projector will

continue to

do so until the button is released.

Mutually Exclusive

Channels can also be defined as mutually exclusive. This will change their functionality

somewhat.A mutually exclusive group is a set of channels in which only one channel of the

set can be turnedon at a time. When a channel is activated in a mutually exclusive set, it turns

on its physical outputfor the time period specified by the keyword being used. However, whenthe physical output stopsthe status does not follow as it normally would. Even after the

physical output stops, the status stillindicates that the channel is on until another channel in

the mutually exclusive set is activated. Thestatus is on to let you know which channel in the

set was last activated. This is sometimes calledlast button pressed feedback.

Before a channel or variable in this set is activated, all the other members of the set are

turned off

beforehand. This is called break before make logic. This prevents an accidental activation of

more than one channel at the same time, which could cause serious damage to some

devices.


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For example, consider the drape and screen channels of the deviceRELAY. Since you cannot

openand close a drape all at once, and you cannot raise a screen and lower it at the same

instant (it coulddamage some motors if you tried!), only one channel can be turned on at a

time. They must be

defined as mutually exclusive. WhenSCREEN_UP is activated, the SCREEN_DOWN channel

is turned

1.Actually, the correct terminology here is the status of all channels is momentary by

default.However, in the common language of programmers, status is understood. From this

pointon in the manual, the behavior of status will be described in this manner.

off andSCREEN_UP turns on. The correspondingSCREEN_UP status stays on even though

the relay

is de-energized when the button is released. WhenSCREEN_DOWN is

activated, SCREEN_UPisturned off. TheSCREEN_DOWN status is now the only status turned on.

You also will define the lighting relays as mutually exclusive so that you can utilize the last

buttonpressed logic when you program the feedback for these buttons. This will allow the

user to look atthe panel and know which lighting preset he or she activated last.

Members of a mutually exclusive set are placed in parentheses underneath the

DEFINE_MUTUALLY_EXCLUSIVEkeyword. The double period (..) shortcut is used to

indicate a

range of channels. The example below would be used to define Mutually Exclusive channels

for the

devices and channels illustrated on FIG. 1 on page 8 of this manual:

DEFINE_MUTUALLY_EXCLUSIVE

([RELAY,SCREEN_UP],[RELAY,SCREEN_DOWN])

//

RELAY CHANNELS 1 AND 2

([RELAY,DRAPE_OPEN]..[RELAY,DRAPE_STOP])// RELAY CHANNELS 4 - 6

([LIGHTS,LIGHT_FULL]..[LIGHTS,LIGHT_OFF])

// LIGHTS CHANNELS 1 - 4

([VCR,PLAY]..[VCR,REW])

// VCR TRANSPORT CHANNELS 1 - 5

([CASS,PLAY]..[CASS,REW])

// CASS TRANSPORT CHANNELS 1 - 5

([CD,PLAY]..[CD,REW])

// CD TRANSPORT CHANNELS 1 - 5

The first set defines the two screen channels as mutually exclusive. Using the shortcut, the

secondset defines the three drape channels as mutually exclusive, and the third set defines

the four lightingrelays as mutually exclusive. The fourth through the last sets also use the


30/93

shortcut to define the fivetransport functions as mutually exclusive. This is done to achieve

last button pressed status forthose decks. When you add the feedback statements to the

program, the buttons for the VCR, CDplayer, and cassette deck will indicate the last button

selected from each group.

Once a channel has its status turned on in a mutually exclusive group, there will always be

one

channel with its status on in that group, unless it is turned off with theTOTAL_OFFkeyword.

The

TOTAL_OFF keyword is used when you need to turn off the physical channel and its status.

Putting it All to Work

Now that you know how all these different types of channels operate, you can skip down to

the

mainline section of the program and add these lines to activate your system power, screen,

drape,

and lighting relays:

BUTTON_EVENT[TP,31]

{

PUSH:

{

ON[RELAY,SYS_POWER]


{

PUSH:

{

OFF[RELAY,SYS_POWER]

}

}BUTTON_EVENT[TP,33]

{

PUSH:

{

PULSE[RELAY,SCREEN_UP]

}


{

PUSH:

{

PULSE[RELAY,SCREEN_DOWN]


31/93

}


{

PUSH:

{

ON [RELAY,DRAPE_OPEN]

}RELEASE:

{OFF [RELAY, DRAPE_OPEN]

}


{

PUSH:

{

TO[RELAY,DRAPE_CLOSE]

}


{

PUSH:{

PULSE[RELAY,DRAPE_STOP]

}RELEASE:

{

OFF[RELAY,DRAPE_STOP]

}


{

PUSH:

{

ON[LIGHTS,LIGHT_FULL]

}


{

PUSH:

{

ON[LIGHTS,LIGHT_MED]


32/93

}


{

PUSH[TP,48]

{

ON[LIGHTS,LIGHT_OFF]

}

}

This section accomplishes several tasks:

! A press of the System Power On button turns on theSYS_POWER channel on the

device

RELAY.

! A press of the System Power Off button turns off theSYS_POWER channel on the

device

RELAY.

! A press of the Screen Up button will pulse theSCREEN_UP channel on deviceRELAY,

after turning offSCREEN_DOWN. The Screen Down button acts the same way as the

Screen Up button, but with the opposite channels. Remember that the PULSE command

will activate the channel for the specified pulse time. The default pulse time is one half

second.

! Pressing Drape Open, Drape Close or Drape Stop does several things. Button event 41is

written

! so that the Drape Open channel will turn on when the button is pressed and off when the

button is released.

! If it is off, it makes sure the other drape channels are off (due to its mutually exclusive

relationship), before it turns on. Button event 42 accomplishes the same thing but it usestheT

O keyword. The TO keyword automatically turns the channel on when the button ispressed

and off when it is released. With theTO keyword, the programmer does not haveto handle

theONand OFF commands with the PUSHand RELEASE of the button. Thesetwo buttons will

do the same thing. When the Drape Stop button is pressed it

willPULSEtheDRAPE_STOP relay on the relay device. The physical relay will only be active

for thepulse but its status (feedback) remains on. (Remember, to turn off the status of a

channelin a mutually exclusive group, use the keywordTOTAL_OFF.)

! Since theLIGHTS channels are mutually exclusive, a press of the Lights Full button turns

on theLIGHT_FULL channel on the device LIGHTS, after turning off any LIGHTSchannel

that was previously on. The otherLIGHTS channels operate in a similar fashion. Sincethis

code is written using theON command both the physical relay and the status of thatrelay will


33/93

stay on indefinitely unless another one of the relays in the Mutually ExclusiveGroup is

pressed. Notice that the program has no way to turn off any of the channels.This is done by

the fact that channels are part of a Mutually Exclusive Group.

Programming Feedback

So far you have been shown how a channels output is affected in a program. You know what

to dowith the input changes and how to create output changes, but now you want to see

some feedbackon your control panel. Feedback refers to the lighting of a button during and

after it is pressed. TheMaster will not do this automatically; you must tell the system how to

light the button. Feedbackinvolves only one statement per button. The first part of the

statement references the device-channelof the button that is going to be lit. It is followed by

an equal sign (=) and the device-channel

corresponding to the source of the feedback, this is called Direct Assignment Feedback. For

example:

[TP,1] = [VCR,PLAY]

The light of touch panel channel one will be on when VCR channel 1 (constant value ofPLAY)

ison. When the channel is off, the light will be off. Remember that any reference to a device-

channelthat does not have the keywordPUSHorRELEASE preceding it is referring to the

output side of thechannel. This is a very important concept, because it is the basis of how

feedback works.

Also recall that one way of creating an output change is to assign a value directly to the

device-channel. If the value that you are assigning is another device-channel reference, this is in

effect

saying to the system, Take the output status of channelPLAY on device VCR, and send it as

an

output change to channel 1 of deviceTP. (In other words, reading from left to right.)"Make

this

([TP,1]) equal to that ([VCR, PLAY])." So the first device-channel pair is going to be changed

to equal the state of the second pair. "Since you defined the device-channel[VCR,PLAY]as

being

Remember that the left side always equals the right side. So, for feedback purposesyou will

always need to list the device channel pairing of the touch panel to the left ofthe device

channel pairing that you wish to tie the feedback to. Touch Panel channel 1must be equal

toVCR channelP L AY. If you write the code the opposite way, the

meaning changes entirely

in a mutually exclusive group, its status will be on if it was the last channel activated in that

set, andthe feedback assignment will light button 1 on the control panel. Once a channel has

feedback on ina mutually exclusive group, there will always be one channel with feedback on

in that group, untilturned off withTOTAL_OFF.


34/93

Grouping Feedback Statements

The feedback statements can be grouped together in a feedback section at the end of the

program.

as shown below:

[TP,1] = [VCR,PLAY]

[TP,2] = [VCR,STOP]

[TP,3] = [VCR,PAUSE]

Direct Assignment feedback statements should only be placed in

theDEFINE_PROGRAM section of

the program, so it will be updated on a regular basis regardless of event status.

It is recommended that you break your feedback into groups with headings. You cancreate

headings by using comments in your program. This will allow the feedback tobe broken into

groups in the Mainline section of code that corresponds to hoe thecode is written in

theDEFINE_EVENT section. For smaller programs this may not benecessary.


35/93

Unit 2: Conditionals and WaitsChapter 5 Conditional ExpressionsIntroduction

While your first program may look complicated at first, it really doesnt show the power of

theAMX programming languages. The program is what we at AMX call one-to-one. That

meansthat each button has one and only one function, with no special conditions or

considerations. Thecontrol panel has a separate section of buttons for each piece of

equipment. (See FIG. 1)

The companion code to this section is called STEP 1a.

PROGRAM_NAME='STEP1'

(* DATE:03/15/02 TIME:12:00:00 *)

(***********************************************************)

(* DEVICE NUMBER DEFINITIONS GO BELOW *)

(***********************************************************)

DEFINE_DEVICE

RELAY= 5001:8:0(*NI-3000 RELAY OUTPUTS 1-8 *)

VCR

= 5001:9:0(*NI-3000 IR OUTPUT #1*)

CD= 5001:10:0 (*NI-3000 IR OUTPUT #2*)


36/93

CASS

= 5001:11:0 (*NI-3000 IR OUTPUT #3*)

LIGHTS = 5001:16:0 (*NI-3000 I/O 1-4*)

TP= 10128:1:0 (*NXT-CV15 TOUCH PANEL*)

(***********************************************************)

(* CONSTANT DEFINITIONS GO BELOW *)

(***********************************************************)

DEFINE_CONSTANT

(* TRANSPORT CHANNEL NUMBERS *)

PLAY= 1

STOP= 2

PAUSE = 3

FFWD= 4

REW

= 5

(* THE RELAY CARD CHANNEL DEFINITIONS *)

SCREEN_UP

=1SCREEN_DOWN = 2SYS_POWER

= 3

DRAPE_OPEN= 4

DRAPE_CLOSE = 5

DRAPE_STOP= 6

(* THE LIGHT CARD CHANNEL DEFINITIONS *)

LIGHT_FULL = 1

LIGHT_MED= 2

LIGHT_LOW= 3

LIGHT_OFF= 4

(***********************************************************)

(* VARIABLE DEFINITIONS GO BELOW *)

(***********************************************************)

DEFINE_VARIABLE

(***********************************************************)

(* LATCHING DEFINITIONS GO BELOW *)

(***********************************************************)

DEFINE_LATCHING


37/93

(***********************************************************)

(* MUTUALLY EXCLUSIVE DEFINITIONS GO BELOW *)

(***********************************************************)

DEFINE_MUTUALLY_EXCLUSIVE([RELAY,SCREEN_UP],[RELAY,SCREEN_DOWN])

([RELAY,DRAPE_OPEN]..[RELAY,DRAPE_STOP])

([LIGHTS,LIGHT_FULL]..[LIGHTS,LIGHT_OFF])

([VCR,PLAY]..[VCR,REW])

([CASS,PLAY]..[CASS,REW])

([CD,PLAY]..[CD,REW])

(***********************************************************)

(* STARTUP CODE GOES BELOW *)

(***********************************************************)

DEFINE_START

PULSE [VCR,STOP]

PULSE [CD,STOP]

PULSE [CASS,STOP]

(***********************************************************)

(* THE EVENTS GO BELOW *)

(***********************************************************)

DEFINE_EVENT

BUTTON_EVENT[TP,1]

{

PUSH:

{

PULSE[VCR,PLAY]

}

}BUTTON_EVENT[TP,2]

{

PUSH:

{

PULSE[VCR,STOP]

}

}BUTTON_EVENT[TP,3]


38/93

{

PUSH:

{

PULSE[VCR,PAUSE]}

}BUTTON_EVENT[TP,4]

{

PUSH:

{

PULSE[VCR,FFWD]

}

}BUTTON_EVENT[TP,5]{

PUSH:

{

PULSE[VCR,REW]

}

}BUTTON_EVENT[TP,9]

{

PUSH:

{

PULSE[CD,PLAY]

}


{

PUSH:

{

PULSE[CD,STOP]}


{

PUSH:

{

PULSE[CD,PAUSE]

}



39/93

{

PUSH:

{

PULSE[CD,FFWD]}


{

PUSH:

{

PULSE[CD,REW]

}


PUSH:

{

PULSE[CASS,PLAY]

}


{

PUSH:

{

PULSE[CASS,STOP]

}


{

PUSH:

{

PULSE[CASS,PAUSE]

}


{

PUSH:

{

PULSE[CASS,FFWD]

}



40/93

{

PUSH:

{

PULSE[CASS,REW]}


{

PUSH:

{

ON[RELAY,SYS_POWER]

}


PUSH:

{

OFF[RELAY,SYS_POWER]

}


{

PUSH:

{

PULSE[RELAY,SCREEN_UP]

}


{

PUSH:

{

PULSE[RELAY,SCREEN_DOWN]

}


{

PUSH:

{

ON [RELAY,DRAPE_OPEN]

}RELEASE:

{

OFF [RELAY, DRAPE_OPEN]


41/93

}


{

PUSH:

{

TO [RELAY,DRAPE_CLOSE]

}


{

PUSH:

{

PULSE[RELAY,DRAPE_STOP]

}


{

PUSH:

{

ON[LIGHTS,LIGHT_FULL]

}


{

PUSH:

{

ON [LIGHTS,LIGHT_MED]

}


{

PUSH:

{

ON [LIGHTS,LIGHT_LOW]

}


{

PUSH:

{

ON[LIGHTS,LIGHT_OFF]}


42/93

}(***********************************************************)

(* THE ACTUAL PROGRAM GOES BELOW *)

(***********************************************************)

(* FEEDBACK *)[TP,1] = [VCR,PLAY]

[TP,2] = [VCR,STOP]

[TP,3] = [VCR,PAUSE]

[TP,4] = [VCR,FFWD]

[TP,5] = [VCR,REW]

[TP,9] = [CD,PLAY]

[TP,10] = [CD,STOP]

[TP,11] = [CD,PAUSE]

[TP,12] = [CD,FFWD]

[TP,13] = [CD,REW]

[TP,17] = [CASS,PLAY]

[TP,18] = [CASS,STOP]

[TP,19] = [CASS,PAUSE]

[TP,20] = [CASS,FFWD]

[TP,21] = [CASS,REW]

[TP,31] = [RELAY,SYS_POWER]

[TP,32] = ([RELAY,SYS_POWER] = 0)

//SYS_POWER RELAY IS OFF

[TP,33] = [RELAY,SCREEN_UP]

[TP,34] = [RELAY,SCREEN_DOWN]

[TP,41] = [RELAY,DRAPE_OPEN]

[TP,42] = [RELAY,DRAPE_CLOSE]

[TP,43] = [RELAY,DRAPE_STOP]

[TP,45] = [LIGHTS,LIGHT_FULL]

[TP,46] = [LIGHTS,LIGHT_MED]

[TP,47] = [LIGHTS,LIGHT_LOW]

[TP,48] = [LIGHTS,LIGHT_OFF]

(***********************************************************)

(* END OF PROGRAM *)

(* DO NOT PUT ANY CODE BELOW THIS COMMENT *)

(***********************************************************)

But suppose you want the same number of functions with fewer buttons. A common solution

is to


43/93

have several groups of buttons with similar functions reduced to one group, with a set of

buttons

that selects which piece of equipment the buttons control. In your program, you could have

one

button for each piece of equipment to select each deck, and one set of transport buttons.

Your panel

could now look like FIG. 2:

FIG. 2G3 Panel with multi-functional transport buttons

The companion code to this section is STEP2a

You now have fewer buttons than you did before. What you want to happen with this panel is

thatthe user selects the deck with a Select button, then controls it with the Transport buttons.

This willnot be a one-to-one program because the Transport buttons each have three possible

functions. Inthe program you will use conditional expressions to select the correct function of

the Transportbuttons. Additionally, the System Power has been reduced to one toggling

button, which will haveits feedback turned on when the system is powered and off when the

system is not powered. Inother words, one button will perform different functions based on a

given condition.


44/93

Conditional Expressions

A conditional expression is used to tell the system whether or not to execute a particular

function orfunctions in the program. Picture yourself walking along a path in the country.

Suddenly you comeupon a fork in the road. Which way should you go? If you guess, you

might become lost. Thereforeyou judge certain conditions before continuing. Is the left road

heading north? Is the right road

heading east?

This is what the Master must do whenever you branch off in different directions in your

program.

Either the Master continues in the direction it is going, or it must jump to a different section.

A conditional expression can have one of two results, true or false. In AMX programming, any

non-zero value is true and a zero value is false. When the Master evaluates a conditional

expression, itassigns a 1 for a true result, and a zero for a false result.

The IF Statement

The most common keyword in AMX programming that uses conditional expressions is theIF

keyword. EveryIF statement must be followed by a conditional expression enclosed in

parentheses. This provides the beginning of a conditional execution of statements. The

structure is

as follows:

IF(conditional expression)

{Statement 1

}

If the conditional expression is true, the Master executes Statement 1 and then continues with

whatever statements follow. If the conditional expression is false, Statement 1 is ignored. The

braces indicate that the statement below the condition is a subset. As such, the subset will

only be

executed if the condition is true.


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The IF...ELSE Set of Statements

This is similar to the basicIF statement, with the addition of one more branch. If the

conditionalexpression is false, the Master executes a function independent of the true

conditional expression.For example:

IF(conditional expression)

{

Statement 1

}ELSE

{

Statement 2

}

If the conditional statement is true, then Statement 1 is executed. Statement 2, underneath

theELSEstatement, is ignored. If the conditional statement is false, then Statement 2 is

executed. Rememberthat Statement 1 is automatically ignored if the expression is false.

Repeating IF...ELSE Set of Statements

Using IF... ELSE allows two different paths for conditional branching. By repeating the

IF... ELSE statements multiple paths can be created. The Master will stop conditional

evaluation

at the first true conditional expression and execute the associated statements. After

completion, it

goes on to the rest of the program. For example:

IF(Conditional expression)

{

Statement 1

}ELSE

{


{

Statement 2}ELSE

{


{

Statement 3

}ELSE

{

Statement 4

}


46/93

}

}

The lastELSE statement placed at the end of the conditional branching operates as a default

statement. That is, if the Master processor does not find a trueIFstatement, it executes the

final

ELSE statement. However, the last ELSE statement is not necessary.

Nesting

Once the Master processor is traversing along anIF branch you can tell it to branch off again

withanotherIF statement. This branch within a branch is called nesting. An IF can be within

an IFwithin anIF, and so on. The only restriction is the amount of memory available.

When you are nesting IF... ELSE statements, be sure to use braces. Look at the following

incorrect example:

IF(X = 5)

{

Statement 1A

IF(Y = 10)

{

Statement 1B

}ELSE{

Statement 2

}}

Even though the alignment suggests the ELSE goes with the first IF, the braces force it to go

withthe second (nested) IF. The secondIFstatement is not supposed to have an ELSE

counterpart inthis example. However, such is not the case. The Master pairs the

secondIFstatement with theELSE, because both are within the compound statement created

by the first and last braces. Byrearranging the braces you can force the compiler to associate

the ELSE with IF(X = 5). Fo rexample:

IF(X = 5)

{

Statement 1A

IF(Y = 10)

{

Statement 1B

}

}ELSE

{

Statement 2}


47/93

By using the braces, you isolate the IF(Y = 10) statement from the IF... ELSE set of

statements.

The SELECT...ACTIVE Statement

There is a way to make nesting easier: theSELECT...ACTIVE statement. This allows the easy

placement of several branches from one path. Here is the format:

SELECT

{

ACTIVE(conditional expression 1):

{

Statement 1

}ACTIVE(conditional expression 2):

{

Statement 2


{

Statement 3

}(* ...etc. *)

}

Each one of the conditional expressions, in order, is evaluated until one is found to be true.

The

statements associated with that true expression are then executed, and the path then flows to

whatever statements follow the closing brace. So if there are five conditional statements to

evaluate

and the second one is true, its statements will be executed. The 3rd, 4th and 5th conditional

statements will never be checked. The processor will go to the statement following the closing

brace of theSELECT...ACTIVE. Using a SELECT...ACTIVEis much preferred to multiple

IF...ELSEstatements; it uses less memory and it runs faster. If too many IF...ELSE

statements are chained together, they can overflow the Master processor memory and crash

theSo what happens in aSELECT...ACTIVE if none of the conditions evaluate as true? In such a

case, no code of anyACTIVE statement will be executed, since SELECT...ACTIVEhas no

default

statement. You can, however, create your own default for aSELECT...ACTIVE:

SELECT

{

ACTIVE(conditional expression 1):

{

Statement 1


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{

Statement 2


{

Statement 3

}ACTIVE(1):

{

Default statement

}

}

Here, the lastACTIVE will always be true (remember in AMX programming a 1 is true and a 0

isfalse), and will execute only if all of the conditions of the previousACTIVE statements are

false.This makes the lastACTIVE statement the default statement.

Trying it Out

Now you can write the code for your new panel layout. Before you do, however, you will need

toupdate your definition sections a little. The preferred method of implementing select

groups is touse one variable and change its value based on which deck is selected.

The Variable Assignment Method

Assigning different values to one variable depending on what is selected is the preferred

method ofprogramming select groups. This method is actually more powerful than other methods, as it

provides more flexibility while using a lot less code.

First add just one variable,DECK to the program you wrote previously. This will be the

selectvariable. For a NetLinx Master you will define the variable to contain NetLinx device

addressinformation by using theD EV keyword as shown below:

! D E F I N E_ V A R I A B LE

! DEV DECK

As we learned early in this manual, there are different types of variables. Meaning that

variables

can hold different types of data.DEV is one type available to you in Netlinx. A DEV variable

can

hold the Netlinx device address information in it. Meaning that if we create a variable

calledDECK

of typeD EV,DECK will be able to store D:P:S info of any of the devices we declared in the

DEFINE_DEVICEsectio n.

Based on the code we already wrote in Step 1,DECK would be able to hold the Netlinx

address


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value ofRELAY, VCR, CD, CASS, LIGHTSorTP. However, we don't want to hold all of these,

we just want to differentiate between which deck we are currently choosing to control.

The code below allows us to use certain buttons to change the value ofDECK. Notice there is

no wayto makeDECK equal to TP. Even though ourDEV variable can hold that information,

that is not whatwe want. We only want to be able to switch between theVCR, CDorCASS.

That is done by using theDevice Select buttons on FIG. 2 on page 32 and the code written

just below:

BUTTON_EVENT[TP,1]

{

PUSH:

{

DECK=VCR

}

}BUTTON_EVENT[TP,2]

{

PUSH:

{

DECK=CD

}

}BUTTON_EVENT[TP,3]

{PUSH:

{

DECK=CASS

}

}

You can reduce the number of transport sections from three to just one by using the

variableDECK

as the device number in thePULSE statements, instead of using VCR, CD, and CASS. Heres

the

section of code:

BUTTON_EVENT[TP,17]

{

PUSH:

{

PULSE[DECK,PLAY]

}



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{

PUSH:

{

PULSE[DECK,STOP]

}


{

PUSH:

{

PULSE[DECK,PAUSE]

}


{

PUSH[TP,20]

{

PULSE[DECK,FFWD]

}


{

PUSH:

{PULSE[DECK,REW]

}

}

Notice that noIF statement and no mutually exclusive variables are necessary for the variable

DECK, and this is the only deck transport section of programming needed in the whole

program! But

how does this work? Suppose you want to play theCD player. First you press theCD Select

button.This assigns the value5001:10:0 (the constant value of CD device) to the

variable DECK. Now thedevice-channel references of thePULSE transport statements will

reference device number

5001:10:0 (the CD device). Pressing button number 17 on the Touch Panel will activate

[DECK,PLAY], which the Master will interpret as [5001:10:0,1].

The feedback for the transport section works in the same manner as the control section. The

feedback statements use theDECK variable as the device from which to get the feedback.

These

statements for the selection buttons, however, are something new:


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[TP,1] = (DECK=VCR)

[TP,2] = (DECK=CD)

[TP,3] = (DECK=CASS)

These statements, like all feedback statements, are direct assignment output changes;

however, the

source of the assignment is a conditional expression. In interpreting this kind of feedback

statement, the master first evaluates the conditional expression. If the expression is evaluated

as

true, the expression is replaced with a 1; otherwise it is replaced with a zero. (Remember,

only one

of these will be evaluated as true because a variable cannot have two different values at one

time.)

Thus the direct assignment will assign a 1 (on) to the Touch Panel button for which the

expression is true, and a zero (off) to the false ones. Recall that assigning a 1 to a device-

channel

is the same as turning the output of a device-channel on

Conditional Operators

The previously discussedIF andIF...ELSE statements can only base the program flow on

onecondition. You can, however, combine two of these conditions with a conditional operator.

Thisoperator sets the rules for determining the end result.

The conditional operators used in AMX systems areAND, OR, XOR, and NOT. These areplaced in

between the two conditions after theIF statement. For example:

IF((X = 10) AND (Y = 5))

{

Statement 1

}

For this condition to be met, 2 things have to be true. X must be equal to 10 and Y must be

equal to5. If the end result of the conditional expression is true, the system continues with

Statement 1. Ifthe end result is false, the system simply ignores Statement 1.

In most conditional expressions, the possible conditions of two statements are analyzed to

achieve

one result. A text formula can be followed to find that result:

""If , then the result of the expression is true or false."

The result is found by basing the conditions of the statements against the rules set by the

conditional operator. Here are those specific rules:


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AND

Both statements must be true for the result to be true.

OR

At least one of the conditions must be true for the result to be true.

XOR

Only one statement can be true for the result to be true.

NOT

If the statement is true, the result is false. On the contrary, if the condition is false, the

result is true. This expression uses only one statement.

Consider the followingIFstatement:

IF((NUM1 = 5) AND (NUM2 = 4))

Assume that it has been previously defined that NUM1 = 5 and NUM2 = 3. Insert the

variables from

the example into the text formula:

IfNUM1 = 5 is true and NUM2 = 4 is false, then the result of the expression is false.

The statement would have been true ifNUM2 had been equal to 3, because in

anAND expression both

statements must be true.

We can use theNOT operator to allow us to program the single power button on this touch

panellayout. Since the state of an output channel can be on (1) or off (0), using

theNOT operator on adevice channel will change its state from off to on or on to off. The codefor this button is shownbelow:

BUTTON_EVENT[TP,31]

{

PUSH:

{

[RELAY,SYS_POWER] = NOT[RELAY,SYS_POWER]

}

}

Each press of the button will toggle the state of theSYS_POWER relay. If we did not use the

NOToperator to toggle the state, ofSYS_POWER we would have to write out the conditional

evaluationsand each action separately. The code below does the same thing without

theNOT operator. Noticethe extra lines of code required.

BUTTON_EVENT[TP,31]

{

PUSH:

{

IF ([RELAY, SYS_POWER])


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{

OFF [RELAY,SYS_POWER]

}ELSE IF ([RELAY, SYS_POWER]=0)

{

ON [RELAY, SYS_POWER]

}

}

}

The feedback for this button will track the state of the relay channel:

[TP,31] = [RELAY,SYS_POWER]

This would work with either method of code above.

The conditional operators can be abbreviated in your program as shown below:

Condional operator Abbreviations

Abbreviation Function Abbreviation Function

&& Logical AND & Bitwise AND

II Logical OR I Bitwise OR

^^ Logical XOR ^ Bitwise XOR

! Logical NOT ~ Bitwise NOT


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Chapter 6 The Wait KeywordsControlling Time Within the AMX System

Within the AMX system there are a variety of timing keywords available for your use.

Functionscan be delayed for a few seconds, or they can be delayed until certain conditions

are right. Thischapter will help you learn each of these keywords and show you how to apply

them to yourprograms.

You will build on your previous program, but this time you will not be changing the layout of

your

Touch Panel, youll just add more functions to the existing buttons.

The WAIT List

The most common keyword relating to time is theWAIT keyword, which is used to activate

functions after a specified delay time has elapsed. The program flow does not stop when

aWAITis

encountered. Instead, the Master places the statement associated with theWAIT keyword into

a list

in memory and continues on with the rest of the program. The Master scans this list, and if

any

WAITs have come due, the Master executes the statement or compound statement

associated with

the expiredWAIT keyword. Up to 50 WAIT references are allowed in the list at a time.

Time in theWAIT list is measured in tenths of a second. A WAIT of 10 is one second,

a WAIT of 15

is one and a half seconds, aWAIT of 20 is two seconds, and so on.

Suppose in your system you have two relays controlling system power. One is for the audio

amplifier, and the other is for the rest of the equipment (well call that rack power). In many

cases, a time delay is desired between powering up the source equipment and powering up

the

audio amplifier. The reason is that if both are powered up at the same time, there is

sometimes a

loud pop over the audio system from the source equipment; but if there is a delay, the

source

equipment is already on and there will be no pop when the amp is turned on. In most cases

a one

half-second delay is enough.

In your program, you will first add a constant definition for your new relay and change the

name ofthe existing system power relay toRACK_POWER. If you use relay 7 (the next

available relay on thecard), the line to add to the DEFINE_CONSTANT section

is: AMP_POWER = 7


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The companion code to this section is STEP3a.

As for the System Power button, you want the rack power to come on first (relay 3) when the

power

is turned on; one half-second later, the amp power should turn on. When you turn the power

off,you want the reverse to happen. First, look at the organization of this set of statements.

Here is asimplified outline of the structure of this code:

BUTTON_EVENT[TP,31]

{

PUSH:

{

IF (device-channel)

{

compound statement

}ELSE

{

compound statement

}

}

From this outline you can more easily examine what is happening here. Following thePUSH

statement is a singleIF...ELSE statement which has only a device-channel reference for its

condition. In this case the Master checks that channels status. If it is on, the Master evaluatesthe

condition as true and executes the first compound statement. Otherwise the compound

statement

following theELSE is executed.

Heres the new code for the System Power button:

BUTTON_EVENT[TP,31]

{

PUSH:

{

IF([RELAY,RACK_POWER])

{

OFF[RELAY,AMP_POWER]

WAIT 5

{

OFF[RELAY,RACK_POWER]

}

}ELSE


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{

ON[RELAY,RACK_POWER]

WAIT 5

{

ON[RELAY,AMP_POWER]

}

}

}

}

The first compound statement, which is executed if the rack power is on, uses aWAIT to

accomplisha time-delayed powering-down of the system. The first statement inside the

compound statementturns off the amplifier relay. The next statement is aWAIT statement for

five-tenths of a second

(same as one half-second), followed by anOFF statement to the rack power relay. The Master

places thisWAIT into the WAIT list and continues with the program. Since these statements

are part

of anIF compound statement, the Master does not execute the compound statement following

the

ELSE.

As the system continues to run, theWAIT is still in the WAIT list. After one half-second has

elapsed,the Master will execute the statement immediately following theWAIT, which in thiscase turns offthe rack power. The correspondingWAIT is then taken out of the list.

The compound statement following theELSE is nearly the same as the one just described; its

functions are just slightly different. The Ma

amx programing course

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