No Communication

Symptom Possible Cause Corrective Action
Temperature data is displayed as a value between -99999 and -100001 Modbus address of sensor node is different than the queried address. Connect a single node and query its temperature using the universal address of 251.
No/Insufficient Power. Use a DVM to verify power is getting through to the receptacle (bottom) port of the final node on the string. Measurement between Pins 4 and 7 must be 5-24V.
String disconnected or incorrect wiring. Inspect the string’s connection to the DCP. Switch the sensor’s RS485A and RS485B leads (naming convention is not standardized acrossed devices).
Water ingress into one or more cable/sensor connections on the string. Inspect cable and sensor plug and receptacle O-rings. If necessary, clean connector pins with 91% Isopropyl Alcohol and Q-tips and dry with compressed air.