Allen-Bradley MicroLogix 1200 Reference Manual page 255

PLC 5 Gain Range (RG)
Tuning Parameter Address
Descriptions
RG - PLC 5 Gain Range PD10:0/RG
When set (1), the reset (TI) and gain range enhancement bit (RG) causes
the reset minute/repeat value and the gain multiplier (KC) to be divided
by a factor of 10. That means a reset multiplier of 0.01 and a gain
multiplier of 0.01.
When clear (0), this bit allows the reset minutes/repeat value and the gain
multiplier value to be evaluated with a reset multiplier of 0.1 and a gain
multiplier of 0.1.
Example with the RG bit set: The reset term (TI) of 1 indicates that the
integral value of 0.01 minutes/repeat (0.6 seconds/repeat) is applied to
the PID integral algorithm. The gain value (KC) of 1 indicates that the
error is multiplied by 0.01 and applied to the PID algorithm.
Example with the RG bit clear: The reset term (TI) of 1 indicates that the
integral value of 0.1 minutes/repeat (6.0 seconds/repeat) is applied to the
PID integral algorithm. The gain value (KC) of 1 indicates that the error is
multiplied by 0.1 and applied to the PID algorithm.
The rate multiplier (TD) is not affected by this selection.
NOTE
Setpoint Scaling (SC)
Tuning Parameter Address
Descriptions
SC - Setpoint Scaling PD10:0/SC
The SC bit is cleared when setpoint scaling values are specified.
Loop Update Too Fast (TF)
Tuning Parameter Address
Descriptions
TF - Loop Update Too PD10:0/TF
Fast
The TF bit is set by the PID algorithm if the loop update time specified
cannot be achieved by the controller due to scan time limitations.
If this bit is set, correct the problem by updating your PID loop at a
slower rate or move the PID instruction to an STI interrupt routine. Reset
and rate gains will be in error if the instruction operates with this bit set.
Process Control Instruction
Data Format Range Type
binary (bit) 0 or 1 control
Data Format Range Type
binary (bit) 0 or 1 control
Data Format Range Type
binary (bit) 0 or 1 status
Publication 1762-RM001C-EN-P
19-13
User Program
Access
read/write
User Program
Access
read/write
User Program
Access
read/write