What it means
Communication between STS system modules has failed.
This entry is tied to the exact STS message family documented by Sullair. The same words can mean something different on another controller generation, so confirm the displayed message and machine documentation before acting.
Likely causes
- Module network communication failure between display, I/O and/or other modules
- Wiring or connection fault
Operator-safe first checks
- Record whether the display is responsive and which other messages are present.
- Do not disconnect controller network cables while the machine is running unless the OEM procedure allows it.
Trained maintenance / service checks
- Inspect module-network wiring and connectors.
- Verify module power and communication integrity per the STS service procedure.
Reset or keep running?
Do not use repeated resets as a substitute for diagnosis. If the condition involves electrical power, a motor overload, high pressure, loss of cooling, abnormal temperature, or a safety circuit, correct the underlying problem before returning the compressor to service.
Source confidence
OEM VERIFIED
This message and its troubleshooting direction are traced to the Sullair STS controller troubleshooting guide.
Source: Sullair STS Controller User Manual, part 02250241-178 R01. Referenced manual page: 32.