program struct control inst

7/28/2019 Program Struct Control Inst

1/10

SIMATIC S5

Methods of Programming

1-10

Linear Structured

All Instructions are contained

in one block (OB1). Linear Programming is like a

fixed -wired logic.

All instructions are repeatedly

carried out line by line

This block is executed continuously.

Reusable functions are loaded

into individual blocks. OB1 calls up these blocks and

passes on the relevant data.

Some concrete information is

made available to the instruction

for jumping from one block to the

other block.


2/10

SIMATIC S5

2-10

Statement 1

Statement 2

...................

....................

....................

........................................

Block End

OB1

JU PB10

Statement 2

...................

JU FB10

....................

........................................

Block End

JU PB20

Statemt 2

BE

Statemt 1

BE

Statemt 1

BE

OB1 PB10 PB20

FB10

Linear Structured


3/10

SIMATIC S5

STEP - 5 SOFTWARE BLOCKS

Organisation Block Organisation block forms the interface between

operating system and the user program.

Organisation blocks are divided into 2 categories : -

1> Those called by system in response to events.

2> Those called by user.

OBs called by system program control:-

- Cyclic.- Interrupt - driven.

- Time - controlled program execution.

It is user programming block. Only basic operations may be programmed in these blocks

It is mainly used for programming various process related

functions (eg. actuators , sensors, limit switches etc. )

Programming Block

3-10


4/10

SIMATIC S5

STEP - 5 SOFTWARE BLOCKS

Function BlockFunction blocks are special blocks for programming

frequently recurring parts of program.

FBs are divided into two types :

1> Standard or Pretested function blocks.

2> Programmable function blocks.

In FB it is possible to assign the parameters or operands. Only STL programming is possible.

Data blocks store data needed to process a control program. Example: Actual Values.

Limiting Values.

Result of arithmetic operation etc.

Data Block

4-10


5/10

SIMATIC S5

Program Control Instructions

5-10

JC : Jump ConditionallyProgram Scanning jumps to different Blocks

when the RLO is 1.

Otherwise continues in the same Block.

JC PB 100

PB 20 PB 100

A I 0.0


6/10

SIMATIC S5


6-10

BE : Block EndThe BE operation terminates the Block. The Data Block need not be terminated.

JU PB 100

OB1 PB 100

BE


7/10

SIMATIC S5


7-10

BE : Block EndThe BE operation terminates the Block. The Data Block need not be terminated.

JU PB 100

OB1 PB 100

BE


8/10

SIMATIC S5


8-10

BEU: Block End Unconditionally

JU PB 100

OB1 PB 100

BEU

BE

BEC: Block End Conditionally

JU PB 100

OB1 PB 100

BEC

BE

A I 0.0

Block is ended when RLO is 1

otherwise it continues with next

statements.


9/10

SIMATIC S5

Result of Logic Operation with Block End Operations BE and BEC

9-10

= Unconditional block end

RLO remains unchanged until the next signal state check.

= Conditional block end

Yes No

Return to block previously being executed

RLO remains unchanged.

RLO remains unchanged until the next signal state check operation !

No return !

RLO changes from '0' to '1'.

Return to block previously being executed.

BE, BEU

A I 0.4

BEB

RLO = '1'?


10/10

SIMATIC S5

3-27

Result of Logic Operation with Jump Operations JU and JC

10-10

= Unconditional block call

Jump to block PB xxx

RLO remains unchanged until the next signal state check.

= Conditional block call

Yes No

Jump to block PB xxx

RLO remains unchanged.

RLO remains unchanged until the next signal state check operation!

No jump !

RLO changes from '0' to '1'.

JU PB xxx

A I 0.3

JC PB xxx

RLO = '1'?

program struct control inst

Documents