Allen-Bradley SLC 500 Series

Publication 1747-RM001G-EN-P - November 2008
9-10 Proportional Integral Derivative Instruction
Control (CM)
Control mode, or forward-/reverse-acting, toggles the values E=SP-PV and
E=PV-SP.
When set (1) - Forward acting (E=PV-SP) causes the control variable to
increase when the process variable is greater than the setpoint.
When cleared (0) - Reverse acting (E=SP-PV) causes the control variable to
decrease when the process variable is greater than the setpoint.
Deadband (DB)
This bit is set (1) when the process variable is within the zero-crossing
deadband range.
Reset and Gain Enhancement Bit (RG)
When set (1), the reset and gain range enhancement bit (RG) causes the reset
minute/repeat value (TI) 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.
Table 9.11 Control Mode Parameter
Tuning Parameter
Descriptions
Address Data Format Range Type User Program
Access
CM - Control Mode Word 0, Bit 2 binary (bit) 0 or 1 control read/write
Table 9.12 Deadband Parameter
Tuning Parameter
Descriptions
Address Data Format Range Type User Program
Access
DB - PV in Deadband Word 0, Bit 8 binary (bit) 0 or 1 status read/write
Table 9.13 Reset and Gain Parameter
Tuning Parameter
Descriptions
Address Data Format Range Type User Program
Access
RG - Reset and Gain
Enhancement
Word 0, Bit
4
binary (bit) 0 or 1 control read/write