Watlow CLS - Manual (Page 35)

Installation
CLS User’s Guide 27
Outputs
NOTE
Your CLS is shipped with heat outputs enabled and cool
outputs disabled. You can disable any PID output and use it
for other digital output functions.
All digital outputs and PID outputs are sink outputs referenced to the
5Vdc supply. These outputs are Low (pulled to common) when they are
On.
All digital inputs are Transistor-Transistor Logic (TTL) level inputs
referenced to control common.
The control outputs are located on the 50 pin header which connects to
the TB-18 or TB-50 pin flat ribbon cable. This section explains how to
wire and configure them.
Wiring Outputs
The CLS provides dual PID control outputs for each loop. The digital
outputs sink current from a load connected to the CLS's internal power
supply or from an external power supply referenced to CLS ground.
• If you use an external power supply, do not exceed +12 volts.
• If you tie the external load to ground, or if you cannot connect it as
shown below, then use a solid state relay.
• If you connect an external supply to earth or equipment ground, use
solid state relays to avoid ground currents. (Ground currents may
degrade analog measurements in the CLS).
The outputs conduct current when they are “True”. The maximum
current sink capability is 20 mA (when all outputs are used). They
cannot “source” current to a ground load