Decision Tree: Communication / DCS
Goal: restore stable updates to DCS/PLC/Historians (values + quality + update timing).
1) Confirm analyzer is running analysis normally (latest run time updating).
2) Check physical/network basics: link lights, correct IP/subnet/gateway, ping test.
3) Verify protocol settings: Modbus TCP / OPC / serial gateway match DCS config.
4) Verify mapping/scaling: register list, data types, scaling, and quality/status mapping.
5) Align DCS polling interval with GC cycle time (avoid timeouts).
Quick Symptoms → Likely Cause
All values stale: IP/network, service down, wrong port.
Values update but wrong: mapping/register offset, scaling, wrong data type.
Bad quality only: quality/status mapping, handshake, polling mismatch.