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4.10 PID Control Block Parameter List

Parameter

Rel.

Index

Description Type Store

Size

byte

RO /

R/W

Min. Max. Default

ST_REV

The revision level of the static data associated with the

function block. To support tracking changes in static para-

meter attributes, the associated block’s static revision

parameter will be incremented each time a static parameter

attribute value is changed. Also, the associated block’s

static revision parameter may be incremented if a static

parameter attribute is written but the value is not changed.

Un-

signed

SRC 2 RO 0

TAG_DESC

The user description of the intended application of the

block.

Octet

String

SRC 32 R/W spaces

STRATEGY

The strategy field can be used to identify grouping of

blocks. This data is not checked or processed by the block.

Un-

signed

SRC 2 R/W 0

ALERT_KEY

Contains the identification number of the plant unit. It helps

to identify the location (plant unit) of an event.

Un-

signed

SRC 1 R/W 1 255 0

MODE_BLK

Contains the current mode and the permitted and normal

mode of the block.

DS-69 Mix 4 Mix O/S

BLOCK_ERR

This parameter reflects the error status associated with the

hardware or software components associated with a block.

It is a bit string, so that multiple errors may be shown.

Bit

String

D 2 RO

Either the primary analog value for use in executing the

function, or a process value associated with it. May also be

calculated from the READBACK value of an AO block.

DS-65 D 5 RO

8 The analog setpoint of this block. DS-65 N 5 R/W

PV_SCALE

±10%

OUT

The primary analog value calculated as a result of executing

the function.

DS-65 N 5 R/W

OUT_SCALE

±10%

PV_SCALE

The high and low scale values, engineering units code, and

number of digits to the right of the decimal point to be used

in displaying the PV parameter and parameters which have

the same scaling as PV.

DS-68 SRC 11 R/W 0-100%

OUT_SCALE

The high and low scale values, engineering units code, and

number of digits to the right of the decimal point to be used

in displaying the OUT parameter and parameters which

have the same scaling as OUT.

DS-68 SRC 11 R/W 0-100%

GRANT_DENY

Options for controlling access of host computer and local

control panels to operating, tuning and alarm parameters of

the block.

DS-70 SRC 2 R/W

CONTROL_OPTS

Options which the user may select to alter the calculations

done in a control block.

Bit

String

SRC 2 R/W 0

STATUS_OPTS

Options which the user may select in the block processing

of status.

Bit

String

SRC 2 R/W 0

The primary input value of the block, required for blocks

that filter the input to get the PV.

DS-65 N 5 R/W

PV_FTIME

Time constant of a single exponential filter for the PV, in

seconds.

Float SRC 4 R/W Positive 0

BYPASS

The normal control algorithm may be bypassed through this

parameter. When bypass is set, the setpoint value (in per

cent) will be directly transferred to the output. To prevent a

bump on transfer to/from bypass, the setpoint will automati

cally be initialized to the output value or process variable,

respectively, and the path broken flag will be set for one

execution.

Un-

signed

SRC 1 R/W 1 2 0

CAS_IN

This parameter is the remote setpoint value, which must

come from another Fieldbus block, or a DCS block through

a defined link.

DS-65 N 5 R/W

SP_RATE_DN

Ramp rate at which downward setpoint changes are acted

on in Auto mode, in PV units per second. If the ramp rate is

set to zero, then the setpoint will be used immediately. For

control blocks, rate limiting will apply only in Auto. For out

put blocks, rate limiting will apply in Auto, Cas, and RCas

modes.

Float SRC 4 R/W Positive +INF

SP_RATE_UP

Ramp rate at which upward setpoint changes are acted on

in Auto mode, in PV units per second. If the ramp rate is set

zero, then the setpoint will be used immediately. For con

trol blocks, rate limiting will apply only in Auto. For output

blocks, rate limiting will apply in Auto, Cas, and RCas

modes.

Float SRC 4 R/W Positive +INF

SP_HI_LIM

The setpoint low limit is the lowest setpoint operator entry

that can be used for the block.

Float SRC 4 R/W

PV_SCALE

±10%

100

SP_LO_LIM

The setpoint high limit is the highest setpoint operator entry

that can be used for the block.

Float SRC 4 R/W

PV_SCALE

±10%

1 2 ... 28 29 30 31 32 33 34 35 36 37

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Wika T53 Manuel d'utilisateur Page 33

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