Watlow PPC-2000 - Manual (Page 133)

PPC-2000 User’s Guide Chapter 3: Operating with AnaWin 3
Doc.# 30002-00 Rev 2.3 Watlow Anafaze 109
Figure 3.9 The Secondary Channel’s Set Point is
Determined by the Primary Channel’s
Process Variable
Ratio Control
Using ratio control the process variable of one channel or any
analog input can determine the set point of another channel.
With ratio control the set point of the ratio channel is
calculated by multiplying the process variable value of the
master channel by a ratio then adding an offset.
Set Point Ratio and Set Point Offset are user set parameters. By
adjusting these parameters, you can adjust the relationship
between the process variable of the master channel and the set
point of the ratio channel. Figure 3.10 on page 110 illustrates
this relationship.
The set point of the ratio loop is limited by the settings of Max
Set Point and Min Set Point.
Set Point of the Secondary Channel
(Engineering Units)
Primary Channel’s Process Variable (°F)
Primary Channel’s Heat Output
(% of Full Scale)
0% 50% 100%
150°F 145°F 140°F
190°F
170°F
150°F