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Tagged: Modbus TCP/IP
I have a project where we are integrating with Modbus TCP/IP network through a third party gateway. The protocol we use is BACnet and our gateway translates from BACnet to Modbus TCP/IP. I was wondering if someone can tell me if the Node ID (what I consider the MAC address)of my gateway needs to be specified for communication to work. From my conversations with the PLC contractor we are integrating with, he is of the opinion that specifying the Node ID (MAC address is not necessary).
If any one has some input to this, please don’t hesitate to respond.
Typically Node ID or Unit ID is used on the Modbus network. The Client on the Modbus side needs to know which Node ID/Unit ID to communicate with. These IDs should be unique. On the BACnet MS/TP network, there is a Device Instance as well as a MAC ID that needs to be unique on the network as well. The MS/TP Master will use the Device Instance and MAC ID for communication. In our gateway, the two sides are clearly defined so they are easy to setup. Also, each side can be troubleshooted independently.
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