Watlow PPC-2000 - Manual (Page 206)

Chapter 5: LogicPro and Modbus Reference PPC-2000 User’s Guide
180 Watlow Anafaze Doc.# 30002-00 Rev 2.3
Setpoint
The setpoint is the desired value for the process variable. The
setpoint may be set to any value within the range of the type of
the input selected as the Process Variable Source for the channel.
If the setpoint set is out of the defined range, the controller
assigns the closest number within the range.
Control Mode
This parameter indicates the mode of control for the channel.
Table 5.13 lists and describes the values to which this
parameter can be set.
Table 5.18 Control Mode
Heat/Cool Feedback Value
The raw output value in parts per thousand (0.1%) calculated
by the PID algorithm. In a normal control loops this value is
filtered with the output filter before it becomes the Heat Output
or Cool Output.
Heat/Cool Proportional Band (Heat/Cool Prop Band)
The proportional band is used to calculate PID output. Larger
numbers result in less proportional action for a given error or
deviation from setpoint. This parameter is set in engineering
units to a positive value less than the sensor range.
Heat/Cool Integral
The integral term controls the amount of influence the history
of error has on the output. Increasing the integral value
decreases the integral contribution to the output. Zero is a
special case that disables integral action. This value is in
seconds per repeat.
Value Mode Description
0 Off
Control algorithm is inactive and no output
is set.
1 Manual
Output is set by the user or a logic program.
See
Heat Output and Cool Output in this
section.
2 Auto
Output is determined by the PID or on/off
control algorithm.
3 Tune
The PPC determines and sets the propor-
tional band, derivative and integral parame-
ters for the channel by setting the output
and measuring the system’s response. See
Autotuning on page 93 .