Pi ctrl – Rockwell Automation 1336T Function Block Prog. Manual, Series A/B User Manual

Page 100

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Function Block Library

4–38

1336 FORCE — 5.9 August 1995

PI CTRL

BLOCK TYPE 17 decimal 11 hexadecimal

IN

PI Controller

ID =

Exec =

NODE 0

In

+

Lo Lim

NODE 9

Hi Lim

NODE 10

Output

NODE 11

In Dif

NODE 12

NODE 1

In

-

NODE 5

KI

NODE 6

KP

NODE 7

Min

NODE 8

Max

NODE 4

Gain

NODE 3

Preset

NODE 2

Set

OUT

KP

KI

DEFINITION

A proportional/integral control function block that uses trapezoidal
integration.

INPUTS

IN1+ — A signed input integer to the PI block.

IN1– — A signed input integer to the PI block.

Set — A logic signal that when

0 sets the integral term’s

accumulator to the Preset value.

Preset — A signed integer that is preloaded into the integrator’s
accumulator when Set = true.

Gain — A scaled, signed integer that adjusts the In+

&

In–

summing node. Scaling: 2048 = effective gain of 1.

KI — A word value that represents integral gain.
Scaling: 4096 = effective gain of 1, max effective gain of 8.

KP — A scaled word value that represents proportional gain.
Scaling: 4096 = effective gain of 1, max effective gain of 8.

Min — A signed integer that limits the lower value of the output
and the integral accumulator.

Max — A signed integer that limits the upper value of the output
and the integral accumulator.

OUTPUTS

Lo Lim — Low limit flag that is true when the calculated
Output < Min.

Hi Lim — Hi limit flag that is true when the calculated
Output > Max.

Output — A signed integer representing the output of the PI
controller.

In Dif — A signed integer that represents the difference between
In+

&

In–. This value is limited to

±

32767 and will not

represent the internal difference if it is not within these
limits.

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