Rockwell Automation 1772-L8_LW_LWP_LX_LXP,D17726.5.8 User Manual - Manual (Page 217)

EAF
Process Control Instructions
Chapter 16
16-6
In both cases, PID data must be limited to a range of 0-4095. Set your
analog input and output modules accordingly (by selection or by default in
most analog modules).
The PID Output (resultant address) is always formatted in 12-bit binary,
with a range of 0-4095. Scale your output module accordingly. If the
module cannot be scaled to 0 to 4095 (for example, 1771-IR and -IX), the
input range must be descaled (refer to the section on descaling inputs on
page 16-23).
Tieback Input
Tieback is an optional input used only when a hardware automatic/manual
station is connected. It allows the PID instruction to track the station for
bumpless transfer from manual to automatic. If Tieback is not needed,
program its Get instruction with a dummy address.
PID Control Block
The control block is 24 words long. You need the control block to enter
parameters, their signs, and selected features. Use a File-to-File Move
(File 10) and then a Hexadecimal Data Monitor (Display 1) to display and
enter data into the control block. We recommend displaying only the first
17 words, since the last 7 words are reserved for use by the instruction.
Set/reset status and sign bits of words 01 and 02 using a Binary Data
Monitor (Display 0).
Each entry in the PID Control Block is displayed in 4-digit BCD.
Parameters that must be entered directly into the control block (Set Output,
Set Point, Feedforward, etc.) must be entered in this format only. For
example, if the feedforward value is binary analog input, it must be
converted to 4-digit BCD before being transferred into the PID
Control Block.
The series D update added two new bits to Control Word 02: the Resume
Control From Last State bit and the Bumpless Transfer With Proportional
Controllers bit.
Resume Control from Last State
The Resume bit is located in the PID Control Block Word 02, Bit 10.
When this bit is set, you can select a PID resume function to be performed
when switching from Program to Run mode.