Modbus TCP (Modbus TCP/IP)
The Modbus request/response messaging protocol carried over a TCP connection between a client and a server.
The network analogy
Plain client/server polling over TCP, much like an SNMP poller, with a small header that pairs each response to its request.
Why it matters for wireless
Modbus TCP rides TCP, so a short wireless stall shows up as delayed responses rather than an immediate fault. The implementation guide notes a communication break can go unseen if it is shorter than the TCP keep-alive timer.
The Modbus Organization describes Modbus as a messaging structure dating from 19791 for client-server communication, available free of charge with no licensing fees. Modbus TCP wraps TCP/IP around the Modbus instruction set and sends every message via TCP to registered port 5022, which IANA lists as mbap, Modbus Application Protocol.
Each request carries an MBAP header whose transaction identifier the server copies into its response. The guide lists HMI and SCADA applications talking to devices among its uses. Ask each vendor how long its client waits for a late response and what it does next.
About this page
Built from 3 sources: 1 standards body or lab and 2 protocol owners and alliances. Researched and drafted with AI assistance, then reviewed and approved by Ben Rutter on . How pages are made
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Cite this page
Plain
Ben Rutter. "Modbus TCP (Modbus TCP/IP)." OT Wireless, published October 5, 2026. https://otwireless.com/glossary/modbus-tcp/
APA 7
Rutter, B. (2026, October 5). Modbus TCP (Modbus TCP/IP). OT Wireless. https://otwireless.com/glossary/modbus-tcp/
BibTeX
@misc{rutter2026modbustcp,
author = {Rutter, Ben},
title = {{Modbus TCP (Modbus TCP/IP)}},
year = {2026},
howpublished = {\url{https://otwireless.com/glossary/modbus-tcp/}},
organization = {OT Wireless},
}