Quantum Ethernet TCP/IP Modbus Application Protocol
C.3 TCP/IP Specific Issues
C.3.1 Broadcast/Multicast
Although broadcast and/or multicast are supported by both IP network address and IEEE 802.3 MAC address, the Modbus Application Protocol does not support either broadcast or multicast at the application layer.
Schneider Automation’s Quantum PLCs use broadcast addressing because they use ARP as the means of locating the destination node. The client interface to the Modbus Application Protocol service on the PLC, the MSTR block, requires the user to provide the destination IP address. Also the embedded stack does use a
C.3.2 TCP Port Number
Schneider Automation has obtained a
This port number allows Schneider Automation to transport various application protocols over with TCP or UDP. The particular protocol is indicated by the value of the proto_id parameter in the mbap_pdu. Currently the only assignment is 0 meaning Modbus Application Protocol.
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