Watlow CPC400 - Manual (Page 82)

Chapter 3: Operation and Setup CPC400 Series User’s Guide
68 Watlow Anafaze Doc. 0600-2900-2000
Any available heat or cool output may be used as a retrans-
mit output. Any process variable may be retransmitted, in-
cluding the input from the same loop.
To get a 4 to 20 mA or 0 to 5V Î (dc) signal, the controller
output signal must be connected to a Serial DAC.
How to Set Up Process Variable Retransmit
1. Configure all of the setup parameters for the primary
loop (the loop whose input signal will be retransmitted).
2. Choose an unused control output to retransmit the in-
put signal. This output may be on the primary loop or
on a different loop.
3. On the secondary loop (the loop whose output will re-
transmit the signal):
• Set up the parameters in the PV retrans menu. See
Process Variable Retransmit Menu on page 125.
• Enable the loop’s output and configure it to meet
the requirements of the application.
4. If the signal is being retransmitted to another controller,
configure the input of that controller to accept the linear
output signal produced by the retransmit output.
Process Variable Retransmit Example: Data Logging
The CPC400 controls the temperature of a furnace. The
thermocouple in one of the zones is connected to the con-
troller and is used for closed-loop PID control. An analog re-
corder data logging system is also in place, and a recording
of the process temperature is required. The recorder re-
quires a linear 4 to 20 mA input signal, which represents a
process variable range of 0 to 1000°F.
Figure 3.8 Application Using Process
Variable Retransmit
CPC400
Furnace
Power
Controller
To Data
Logger
Loop 1 PID Output
Loop 2 PID Output
Heater
Loop 1
Input
Process
Variable
Serial
DAC