Watlow PPC-2000 - Manual (Page 134)

Chapter 3: Operating with AnaWin 3 PPC-2000 User’s Guide
110 Watlow Anafaze Doc.# 30002-00 Rev 2.3
Figure 3.10 Relationship between the Master
Channel’s Process Variable and the
Ratio Channel’s Set Point.
Setting up Ratio Control
To set up ratio control:
1. Set up the master channel as you would for a standard
closed-loop application. See Setting up Control Channels
on page 92.
2. Set up the ratio channel as you would for a standard
closed-loop application.
3. Make the following additional settings on the ratio
channel:
a. For Set Point Source select the analog input that should
be used to determine the set point (the PV Source of the
master channel).
b. Set the Set Point Ratio and Set Point Offset to create the
desired relationship between the analog input’s value
and the ratio channel’s set point.
c. Set the Min Set Point to the lowest set point value the
ratio channel should ever have.
d. Set the Max Set Point to the highest set point value the
ratio channel should ever have.
Set Point of the Ratio Channel
(Engineering Units)
Max Set Point
SP Offset
Sensor
Master Channel’s Process Variable
Sensor
Min Set Point
High
Range Range
Low
SP Offset + Master PV * SP Ratio
(Engineering Units)