Watlow Series D8 - Manual (Page 126)

Chapter 4: Operation and Setup Series D8 User’s Guide
108 Watlow Anafaze Doc. 0600-3120-2000
Typically, a voltage or current source is connected to an ana-
log input on the controller, and this input is configured as the
master loop for ratio control.
Proper scaling resistors must be installed on the input to allow
it to accept the analog input signal.
How to Set Up a Remote Analog Set Point
1. For the master loop (the loop that accepts the input signal
from the external device), set the parameters in the Input
menu.
2. For the ratio loop (the one whose set point is controlled
by the external device), set the parameters in the Ratio
menu. Specify the loop that accepts the input signal as
the master loop.
Remote Analog Set Point Example: Changing a Set Point with a PLC
A PLC provides a 0 to 5 Vdc signal representing 0 to 300° F
as a remote set point input to the D8. The input signal is re-
ceived on loop 1, and control is performed on loop 2. The D8
is equipped with the proper scaling resistors to allow it to ac-
cept a 0 to 5 Vdc input.
Table 4.13 and Table 4.14 show the parameter settings for this
application.
Table 4.13 Parameters Settings for the Master
Loop (Loop 1) in the Example
Menu Parameter Value Comment
Input Input type process
A 0 to 5 Vdc input signal is a process input.
Input Input range high 300˚F The 5 Vdc input signal represents 300° F.
Input Input high signal 100.0%
The controller is equipped with a 0 to 5 Vdc input,
and the input signal is 0 to 5 Vdc, so the signal
covers the full scale of 0 to 100 percent.
Input Input range low 0˚F
The 0 Vdc input signal represents 0° F.
Input Input low signal 0.0%
The controller is equipped with a 0 to 5 Vdc input,
and the input signal is 0 to 5 Vdc, so the signal
covers the full scale of 0 to 100 percent.