The FRD-4 Thermostatic Unit serves as the controller for cool plates in the DNS 80B track.  This unit is known to fail and can cause communication errors in the bake/cool process.

Front view of FRD-4 for DNS 80B

Cool Plate Controller Communication Error in DNS 80B caused by faulty FRD-4

Front view of FRD-4 installed in DNS 80B. Check communication 5V power at the output connectors.

A good way to quickly check whether or not the FRD-4 communication circuit is functional is to check voltage on one of the output cables to cool plate units.  The output cables connect to the right-most ports on the FRD-4. Each of them has a red wire and black wire that carry 5V DC power.  Backprobe one of these connectors while it is connected to a live FRD-4 to verify the 5V power.  If there is no voltage, the communication logic on-board the FRD-4 has suffered critical failure.  Contact GetSpares.com for replacement or repair solutions.