1. Peter Humaj

    Two Modbus implementations with non-standard behaviour

    Lately I met 2 non-standard Modbus servers. I wonder if someone here had a similar experience (and I want to share it, possibly to help others). Case 1: A small custom-build PLC. No matter what read request it receives, it always sends all the registers (13 or 14 if I remember correctly). To...
  2. Peter Humaj

    Modbus passive (scanning) mode - do you use it?

    A colleague of mine asked me to support a passive (scanning) mode for Modbus (RTU/ASCII) in our D2000 communication driver. So I did this week. This way he can use e.g. Moxa NPort to eavesdrop on existing serial communication. The driver analyzes both Modbus requests (starting address & number...
Top