User`s guide

Series D8 User’s Guide Chapter 2: Installation
Doc. 0600-3120-2000 Watlow Anafaze 31
Wiring Control and Digital I/O
This section describes how to wire and configure the control
outputs for the D8 series controller. The D8 provides dual
control outputs for each loop. These outputs can be enabled or
disabled, and are connected through a TB50 or TB18.
NOTE! Control outputs are connected to controller
common when the control output is on. If you
connect external devices that may have a low
side at a voltage other than controller
ground, you may create ground loops. To
prevent ground loops, use isolated solid
state relays and isolate the control device in-
puts.
Output Wiring Recommendations
When wiring output devices, use multicolored, stranded,
shielded cable for analog outputs and digital outputs connect-
ed to panel-mounted solid state relays.
• Analog outputs usually use a twisted pair.
• Digital outputs usually have 9 to 20 conductors, depend-
ing on wiring technique.
Cable Tie Wraps
After you wire outputs to the TB50, install the cable tie wraps
to reduce strain on the connectors. Each row of terminals has
a cable tie wrap hole at one end. Thread the cable tie wrap
through the cable tie wrap hole. Then, wrap the cable tie wrap
around the wires attached to that terminal block.
Digital Outputs
The D8 provides dual control outputs for up to eight loops. By
default, heat outputs are enabled and cool outputs are dis-
abled. If the heat or cool output is disabled for a loop, then the
output is available for alarms or programmable logic. The
CPU watchdog timer output can be used to monitor the state
of the controller; see CPU Watchdog Timer on page 34.