Phase 25: Modbus RTU/TCP

This phase contains 5 sections and 36 checklist topics. Use the interactive phase page to track your own learning progress.

Modbus fundamentals

Master/Client
Slave/Server
Device address
Register
Function code

Modbus RTU

RS-485
A/B wires
Baud rate
Parity
Stop bits
Device ID
Daisy chain
Termination
And 1 more checklist topics

Modbus data

Coil
Discrete input
Input register
Holding register
Read
Write
Register mapping
Scaling

Modbus TCP

Ethernet
IP
TCP
Port 502
Client
Server

Troubleshooting

Wrong address
Wrong baud rate
Wrong parity
A/B reversed
Missing termination
Wrong register
Offset problem
Scaling problem

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slearnauto is an interactive industrial automation learning platform with progress tracking, flashcard quizzes, and interactive phase checklists. While JavaScript is required to track your progress and use the study tools, our complete 46-phase curriculum is available at: