Rockwell Automation 1772-L8_LW_LWP_LX_LXP,D17726.5.8 User Manual User Manual
Page 238

EAF
Process Control Instructions
Chapter 16
16-27
Derivative Gain Constant (Word 06)
When using the Independent Gain Equation, this is the derivative gain
K
D
(sec). When using the Dependent Gains equation, this is the derivative
time constant T
D
(min).
Derivative Uses Error (Word 01, Bit 06)
You can select whether the derivative term in either PID equation acts on
changes in error or process variable. Consider selecting this feature if you
want to accelerate the response to online changes to the setpoint.
Reset (0)
For normal response to set point changes, derivative
acts on the change in PV
Set (1)
For a faster response to set point changes, set this bit to
act on the change in Error
Done Bit (Word 01, Bit 15)
This bit is set/reset by the EAF instruction when new values have
been calculated.
Reset (0)
New values not calculated
Set (1)
New values calculated
Enable Bit (Word 01, Bit 17)
This bit is set/reset by the EAF instruction to change the status of the
PID rung.
Reset (0)
Rung is not enabled
Set (1)
Rung is enabled
Error (E) (Word 16)
The algebraic difference between PV and SP.
Error Sign (Word 02, Bit 07)
This bit is set/reset by the EAF instruction to indicate the polarity of
the error.
Reset (0)
error is negative
Set (1)
error is positive
Equation (Word 01, Bit 00)
This bit is set/reset this bit to choose your PID equation.
Reset (0)
Independent Gain Equation
Set (1)
Dependent Gain Equation