
MDS 05-4131A01, Rev. A MDS iNET ENI Supplement 15
3. MODBUS to MODBUS
TCP SERVER PROTOCOL
3.1 Introduction
NOTE: This section assumes you have an understanding of Ethernet
networking, TCP/IP, and Modbus serial protocols. For more
information, refer to the Modbus-IDA Organization web site:
http://www.modbus.org.
The iNET implementation of the MODBUS to MODBUS TCP server
protocol is limited to act as one of the following:
• A Modbus/TCP client on the LAN port
• A Modbus ASCII server on the serial port
• A Modbus RTU server (user configurable) on the serial port
NOTE: Modbus/TCP functionality is only available on the COM2 port
of the iNET/ENI transceiver.
NOTE: All requests are sent using TCP on registered port 502.
NOTE: The PLC’s User ID must match the last octet of the iNET
Remote’s IP address. See Figure 3-1.
Figure 3-1 PLC User ID Example
PLC
User ID: 23
NET Remote
P Address: 192.158.16.23
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