Pid block diagram, Table 8.16 pid parameters, An internal test parameter – Flowserve 400MD Logix User Manual

Page 52

Index

Origin

Name

Size

Date Type

Default Value

MFG

FUTURE1

Simple

FLOATING_POINT

MFG

PID_BLOCK_TEST

Array

UNSIGNED8

0,0,0,0,0,0,0,0

Table 8.15 Flowserve PID Parameters

Parameter Name

Description/Parameter Contents

PID_FORM

Configuration parameter specifies the IDEAL or ROBUST PID equation to be used: IDEAL PID (default). Non-Interactive form of

a three mode control equation that provides Proportional, Integral and Derivative (PID) control action. Linear and non-linear gain

parameters are available. ROBUST PID. The same as Ideal PID. Additionally, the equation supports a user-config ured lag filter

applied to calculated output value. (See OUT_LAG parameter.) Linear and non-linear gain parameters are available.

ALGO_TYPE

Configuration parameter specifies algorithm type which can be A, B, or C: Type A equation where Proportional, Integral and

Derivative act on ERROR. Type B equation where Proportional and Integral act on ERROR and Derivative acts on PV. Type C

equation where Integral acts on ERROR and Proportional and Derivative act on PV.

OUT_LAG

GAIN_NLIN

Time constant of single exponential LAG filter applied to the OUT parameter (primary output). Units (in seconds). For ideal PID

equation the lag filter is fixed at 1/16 and cannot be configured.

Dimensionless gain factor. When the gain factor is multiplied by absolute value of the error and added to the linear GAIN, the

result is a gain response which is proportional to the deviation. Default is zero, resulting in no response due to non-linear gain

action.

GAIN_COMP

The composite gain quantity including both linear and non-linear gain parameters. (Read-only parameter.)

Table 8.16 PID Parameters

Parameter Name

Description/Parameter Contents

ERROR_ABS

Absolute value of the difference between PV and working set-point. (Read only parameter.)

WSP

Working set-point. This is the set-point value after absolute and rate limits have been applied.

Deviation alarms are computed on this value. (Read only parameter.)

PID_BLOCK_TEST

An internal test parameter.

PID Block Diagram

Figure 8.4 is a block diagram showing the key components of the PID control function block.

Figure 8.4 PID Control Block

Setpoint

SP_RATE_DN
SP_RATE_UP
SP HI LIM

SP_LO_LM

SHED_OPT

Mode Select

BKCAL_OUT

GAIN

RESET

RATE

BAL_TIME

PID Control

CAS_IN

RCAS_IN

RCAS_OUT

BKCAL_IN

Output

OUT_ HI_LIM

OUT_LO_ LIM

BAL_T IME

OUT

TRK_SCALE

Output Track

TRK_IN_D

TRK_VAL

PV_FTIME

PV Filter

BYPASS

Bypass

HI/LO

DEV

Alarm

FF_SCALE
FF_GAIN

Feed Forward

ROUT_IN

ROUT_OUT

WSP

Backward

Path Outputs

Target &

Permitted

Mode

Actual &

Normal