s6 regulatory control

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YOKOGAWA AUSTRALIA Section 6. Regulatory Control

SECTION 6

CS3000

REGULATORY CONTROL

CONTENTS

6 Regulatory Control________________________________________________2

6.1 Types of the Regulatory Control Blocks _______________________________ 2

6.2 I/O Data Handled by the Regulatory Control Blocks ____________________ 46.2.1 Data Value____________________________________________________________ 46.2.2 Data Status____________________________________________________________46.2.3 Input Data ____________________________________________________________56.2.4 Output Data ___________________________________________________________7

6.3 I/O Connections___________________________________________________ 96.3.1 Summary of wiring rules _________________________________________________ 96.3.2 Explanation of I/O Connections __________________________________________106.3.3 Area Connections _____________________________________________________12

6.4 Function Block Processing _________________________________________ 146.4.1 Input Processing ______________________________________________________146.4.2 Output Processing _____________________________________________________156.4.3 Alarm Processing______________________________________________________166.4.4 Block Modes and Statuses_______________________________________________17

6.5 PID Controller Block and Functions_________________________________ 186.5.1 Summary of PID Functions: _____________________________________________196.5.2 Tuning Parameters for the PID Block ______________________________________20

6.5.3 Input/Output Compensation______________________________________________21

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6 Regulatory Control6.1 Types of the Regulatory Control BlocksThe regulatory control blocks vary by the types of data handled and control

computation processing functions provided. The blocks are classified into these

blocks below.

Input indicator blocks

Controller blocks

Manual loader blocks

Signal setter blocks

Signal limiter blocks

Signal selector blocks

Signal distributor blocks

Pulse count input connection block Alarm block

Input Indicator Blocks

Block Code Name

PVI Input Indication BlockInput Indicators

PVI-DV Input Indication Block with deviation alarm

Controller Blocks

Block Code Name

PID PID controller block

PI-HLD Sampling PI controller block

PID-BSW PID controller block with batch switch

ONOFF 2-position ON/OFF controller block

ONOFF-G 3-position ON/OFF controller block

PID-TP Time-proportioning ON/OFF controller block

PD-MR PD controller block with manual reset

PI-BLEND Blending PI controller block

Controllers

PID-STC Self-tuning PID controller block

Manual Loader Blocks

Block Code Name

MLD Manual loader block

MLD-PVI Manual loader block with input indicator

MLD-SW Manual loader block with Auto/Man switch

MC-2 2-position motor control block

Manual Loader

MC-3 3-position motor control block

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Signal Setter Blocks

Block type Code Name

RATIO Ratio set block

PG-L13 13-zone program set block

BSETU-2 Batch set block for flow measurementSignal Setter

BSETU-3 Batch set block for weight measurement

Signal Limiter Block


Signal Limiters VELLIM Velocity limiter block

Signal Selector Blocks


AS-H/M/L Autoselector blocks

SS-H/M/L Signal selector blocksSignal Selectors

SS-DUAL Dual signal block

Signal Distributor Blocks


FOUT Cascade control signal distribution block

FFSUM Feedforward control signal addition block

XCPL Noninteracting control output addition blockSignal Distributors

SPLIT Split control signal distribution block

Pulse Count Input Connection Block


Pulse Count Input

Connection BlockPTC Pulse count input connection block

Alarm Block


Alarm ALM-R Representative alarm block

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6.2 I/O Data Handled by the Regulatory Control BlocksAs a rule, the data transmitted via I/O terminals handled by the regulatory control

blocks is the engineering unit data. Each data item consists of data value and data

status.

6.2.1 Data ValueThe data value is a numeric data that is transmitted in or out of a function

block. The data values handled by the blocks include process variable (PV),

cascade setpoint value (CSV) and manipulated output value (MV).

The data values handled by the regulatory control blocks are numeric data in

engineering unit. However, the data sent to analog output modules and the

data received from input modules are percentage data between 0 % and 100 %,

except those used for temperature measurement.

The data value read into a function block via an input terminal is called input

data, while the value written out of a function block via an output terminal is

called output data.

6.2.2 Data StatusThe data status is a piece of status information that indicates the value and

quality of I/O data. The data status is conveyed as I/O data from one function

block to another via I/O connection along with a data value.

The data status is used to test the existence of exceptional events, such as

process failures and computation errors occurred in the control computation

processing performed by the function blocks.

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6.2.3 Input Data

The input data is numeric data that the function blocks read from input terminals.

The types of input data are shown below:

Process variable (PV) Setpoint value (SV), cascade setpoint value (CSV), remote setpoint

value (RSV)

Input signal values (RV1, RV2, RV3)

Reset limit values (RLV1, RLV2)

Input or Output Compensated value (VN)

Tracking switch (TSW)

Process Variable (PV)

The engineering unit and scale range of raw input signals (RAW) input to an

IN terminal agree with the engineering unit and scale range of data at the

connected destination of the IN terminal. A raw input signal turns into a

process variable (PV) after input processing. Use the function block detail

definition builder to set the engineering unit and scale range. However, the

process variable (PV) of Motor control blocks (MC-2, MC-3) must be an

integer value between 0 and 2.

Setpoint Value (SV), Cascade Setpoint Value (CSV), Remote Setpoint Value (RSV)

The engineering unit and scale range of the setpoint value (SV), cascade

setpoint value (CSV) and remote setpoint value (RSV) agree with the

engineering unit and scale range of the process variable (PV) except in the

function blocks shown below:

Input Signal Values (RV1, RV2, RV3)

The input signal values (RV1, RV2, RV3) are input data handled by the Signal

selector blocks. Use the function block detail definition builder to set the

engineering unit and scale range of input signal values. The input signal values(RV1, RV2, RV3) are regarded as having the same engineering unit and scale

range as those of the selected signal value (PV).

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Reset Limit Values (RLV1, RLV2)

The reset limit values (RLV1, RLV2) are input data that are handled by a

controller block when the reset limit function is used. The reset limit values

(RLV1, RLV2) are regarded as having the same engineering unit and scale

range as those of the manipulated output value (MV).

Input or Output Compensated Value (VN)

The engineering unit and scale range are not defined for input compensated

values (VN) received from the BIN terminal, as the numeric data of input

compensated values (VN) taken in from outside are used directly for input or

output compensation computation.

Tracking Switch (TSW)

The data handled by the tracking switch (TSW) for the TSI terminal must be

an integer value of 0 or 1. 1 and 0 indicate ON and OFF, respectively.

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6.2.4 Output DataThe output data is a numeric data value that is written out of a function block via

an output terminal. The types of output data are shown below:

Manipulated output value (MV)

Auxiliary output values (PV, DPV, MV, DMV) Process variable (PV)

Manipulated Output Value (MV)

Use the function block detail definition builder to set the display form

for the manipulated output value (MV).

MV Display Style:

Select Automatic Determination or User Define. The

default is Automatic Determination.

When Automatic Determination is selected, the engineering

unit and scale range of the manipulated output value (MV)

change according to the connected destination of the OUT

terminal.

When the connection destination is an input terminal of another

function block than SET terminal, self determination must be

selected. When User Define is selected, set the engineering

unit and scale range for the manipulated output value (MV).

For the MV displayed on an instrument faceplate, set whether

to display the engineering unit data as is or to convert the data

into a percentage-unit value first. Use the function block detail

definition builder to set the instrument faceplate display.

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Auxiliary Output Values (PV, DPV, MV, DMV)

The auxiliary output values include PV, DPV, MV and DMV, the

types vary with the function block. The engineering unit and scale

range of the auxiliary output values change in accordance with the

connected destination of the SUB terminal.

Process Variable (PV)

The process variable (PV) can be output directly from the input indicator

blocks. The engineering unit and scale information of the process variable

(PV) vary with the connected destination of the OUT terminal.

If the connected destination is a process I/O module, the

scale range and engineering unit of the output value are

fixed to 0 to 100 and %, respectively.

If the connected destination is another function block, thescale range and engineering unit of the output value agree

with those of the process variable.

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6.3 I/O Connections6.3.1 Summary of wiring rules

1. GENERAL WIRING RULE

A data item must connect to a data terminal

Never connect data item to data item or data terminal to data terminal

Examples:

PVIN

OUTRV

PID ADDIN Out

PV RV

PVI

2. CASCADE RULE

Always connect the OUT terminal to a SET terminal

Note, the OUT terminal must contain the MV. For example, connecting the OUT ofan SS-H (contains PV) will not work. Use the AS-H instead, as it contains the MV in

its OUT terminal.

PID SetP

OutIN PIDPVI

3. SWITCH RULE

The above two rules hold across a switch for the source and destination modules

on either side of it.

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6.3.2 Explanation of I/O ConnectionsAll blocks have terminals that allow the reading or writing of data to another function

block. Each contains data items that other modules read from or write to using

terminals.

For example, when a PVI is connected as an input to a PID, the IN terminal is reading

the PV of the PVI block, as shown below:

PVI - FI100 PID - FIC100

PV PVIN

In other words for PID tag FIC100, IN = FI100.PV

And this value is then assigned to the PV of the PID block.

This is called a Data Reference Connection.

Similarly it is possible to write to a data item in a block from the terminal of a

previous block as shown below:

PID - FIC100 ADD - FQ100

MV RVOut

In other words, for PID tag FIC100, OUT = FQ100.RV

The MV is assigned through the OUT terminal to the RV of the ADD block.

This is called a Data Setup Connection.

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Cascade Connections

This is a special connection type where the data flow is two way, that is, data is being

read and written between two function blocks through the one connection.

The main application for this is a cascade control loop. This is where the output of a(primary) controller inputs to the setpoint of another (secondary) controller, as shown

in the following diagram:

MV -> CSV

MODESV -> MV

Here, the output (MV) of the primary controller is written to the setpoint (CSV) of the

secondary controller.

However, the block mode (CAS, AUT, MAN) of the secondary controller is written

back to the primary controller. If the secondary controller is not in CAS, then it is not

reading the output of the primary controller and it goes into IMAN. While the

primary controller is in IMAN, it's output tracks the setpoint of the secondarycontroller.

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6.3.3 Area ConnectionsIt is possible to connect function blocks that are on different control drawings, or even

in different FCSs. This is done using LINK blocks called:

AREAIN - link between blocks within the same FCS

AREAOUT - link between blocks in different FCSs

To connect blocks between two control drawings in an FCS, use the AREAIN block

as follows:

FI100

PVI

IN

AREAIN Link block

Control Drawing 2Control Drawing 1

FI100.PVFIC200

PID

To write to a block in another control drawing, also use the AREAIN. Note that

AREAIN does not mean input. It means within the same FCS.

FQ100

ADDOUT

AREAIN Link block

Control Drawing 1 Control Drawing 2

FQ100.RV

FIC200

PID

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Cascade connections can be connected in the same way. However, there must be a

link block in each control drawing, as follows:

OUT

AREAIN Link block

Control Drawing 1

FIC200.SET

FIC100

PID

SET

AREAIN Link block

Control Drawing 2

FIC100.OUT

FIC200

PID

Inter FCS Connections

Connections between function blocks in different FCS is carried out in exactly the

same way as described above. However, use the AREAOUT link block instead of the

AREAIN.

When AREAOUT Links blocks are used, an ADL (Area Data Link) block is

automatically set up in the FCS. This manages the transfer of data between the two

FCSs. The scan rate for the data, and other parameters, are setup in the FCSproperties.

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6.4 Function Block Processing6.4.1 Input ProcessingFunction blocks are provided with various types of input processing methods to

convert the input signals for the control calculation and arithmetic calculation.

Input Processing

Input processing is a general term used for processing for the input signal read

from the connection destination of an input terminal, executed by the function

block before the calculation processing. There are various forms of input

processing corresponding to the function block type and the input signal

format.

Input Processing Common to All Regulatory Control Blocks

The Regulatory Control Blocks have the input signals processed as shown in

the figure below. After the processing, the signal becomes process variable

(PV).

Figure - Block Chart of Input Processing Common to All Regulatory Control Blocks

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6.4.2 Output ProcessingOutput processing is a term defining the functions carried out on an output signal

before it is loaded to the final output item (eg, MV). There are various forms of output

processing corresponding to the function block type and the output signal format.

Some forms of output processing are common to Regulatory Control Blocks and

Calculation Blocks, while others are specific to certain particular blocks.

Output Processing Common to Regulatory Control Block

In a Regulatory Control Block, the value obtained from control computation

undergoes output processing, then outputs as the manipulated output variable

(MV), as depicted in the figure below.

Figure - Block Chart of Output Processing Common to Regulatory Control Block

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6.4.3 Alarm ProcessingThis is a function that detects any abnormality in the process from values such as

process variables (PV) and manipulated output values (MV). In order to detect

anomalies in the process, the alarm detection function performs the following alarm

checks:

Alarm Type Status ID

Input open alarm check IOP, IOP-

Input error alarm check PERR

Input high-high and low-low limit alarm check HH, LL

Input high and low limit alarm check HI, LO

Input velocity alarm check VEL-, VEL+

Deviation alarm check DV-, DV+

Output open alarm check OOP

Output failure alarm check CERR

Output high and low limit alarm check MHI, MLO

Connection failure alarm check CND

Alarm definition is configured in the detailed specification for the function block in

the control drawing. The actual alarm levels are configured through the operator

display.

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6.4.4 Block Modes and Statuses

Every module has a block mode. This defines the status of it's function processing.

These are listed below:

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6.5 PID Controller Block and FunctionsThe PID controller block (PID) provides the most general control function to perform

proportional-integral-derivative control based on the deviation of the process variable

(PV) from the setpoint value (SV).

Figure - Function Block Diagram of PID Controller Block (PID)

Reference: IM 33S1B30-01, Section D1.4 & 5.

The above referenced sections provide detailed information about the functions of the

PID controller block. Below is a summary of the main features of the block.

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6.5.1 Summary of PID Functions:

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6.5.3 Input/Output CompensationThe input/output compensation uses the VN input data item as an adder to the PV

or MV of the controller.

As an adder to the PV (input compensation) it can be used for predictive

control. As an adder to the MV (output compensation) it can be used for

feedforward.

Schematically the function works as follows:

BIN

input compensation output compensationVN

++CB CB

xxCK CK

PID

CalculationPV MV++

To select input or output compensation, go to the EDIT DETAIL of the function

block and select the CONTROL CALCULATION tab.

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Example Feedforward application

One of the most common applications for output compensation is feedforward.

This is where a signal is added to the output of a controller. A typical example

is a boiler application.

The boiler level controller calculates a flow demand based on the boiler level.The problem with this is that sudden changes in demand for steam means that

the boiler level can drop a long way before the level controller can correct it.

To provide closer control, the change in steam flow is added to the output of

the steam controller.

That is, if the steam flow increases by 10%, then increase the feed water flow

by 10% (or some factor of it). This can be tuned by setting the CK

(compensation gain) in the tuning panel.

Put the DPV into the SUB

SUBFI100

PVISet to Out ut Com ensation

VN

Boiler

Level

IN OUTLIC100

PID

SET

Feed Water

Flow

IN OUTFIC100

PID

s6 regulatory control

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