1 / Foundations
What Modbus Is ↗
The mental model, why Modbus is still everywhere, and what it deliberately does not give you.
Learn Modbus
FREE · ONLINE
Learn Modbus is a free course for technicians, controls engineers, and integrators. Sixteen modules combine lessons, no-hardware-first labs, quizzes, diagrams, reviewed resources, and protected machine-readable exports from protocol fundamentals through addressing, serial and TCP communications, troubleshooting, safety, and a capstone integration package. One email submission and human verification unlock the course in that browser for 90 days.
- contains:
- 16 modules · lessons · labs · review checks
- covers:
- addressing · function codes · RTU/TCP · troubleshooting
- access:
- free · email required · 90 days per browser
Online · email and human verification required for access
Open the course ↗
Course outline
2 / Foundations
The Message Model ↗
PDU vs ADU, how requests, responses, and exceptions actually look on the wire.
3 / Foundations
Data Tables ↗
Coils, discrete inputs, input registers, and holding registers — the four primitives.
4 / Foundations
Function Codes ↗
Reads, writes, diagnostics, and the codes you'll actually meet in the field.
5 / Addressing & Data Meaning
Modbus Addressing ↗
0-based wire addresses vs 1-based documentation, and how off-by-one bugs are born.
6 / Addressing & Data Meaning
Register Maps ↗
Reading a vendor map and turning it into a reliable, reviewed integration plan.
7 / Addressing & Data Meaning
Data Types ↗
INT16, UINT16, INT32, FLOAT, word/byte order, and the encoding traps you'll hit.
8 / Addressing & Data Meaning
Scaling & Engineering Meaning ↗
Raw register → engineering value with units, scale, and a sanity check at every step.
9 / Physical Network & Transport
Serial Communication Basics ↗
Baud, parity, stop bits, timing — the fundamentals every RTU integrator must own.
10 / Physical Network & Transport
RS-232, RS-422, RS-485 ↗
Topologies, biasing, termination, and why your bus quietly stops working at node 17.
11 / Physical Network & Transport
RTU & ASCII Frames ↗
Frame structure, CRC vs LRC, silent intervals, and reading captures by hand.
12 / Physical Network & Transport
Modbus TCP ↗
MBAP, unit identifiers, ports, and what changes (and doesn't) moving from RTU.
13 / Integration & Real Systems
Gateways & Mixed Networks ↗
TCP↔RTU routing, unit IDs, latency, and how to keep mixed deployments diagnosable.
14 / Integration & Real Systems
Troubleshooting Workflow ↗
A repeatable evidence-first method for diagnosing failed reads, writes, and timeouts.
15 / Integration & Real Systems
Security & Safety ↗
What classic Modbus does not protect, write safety practice, and TLS / Modbus Security.
16 / Capstone
Capstone: Real Device Integration ↗
Bring a real or simulated device online with a reviewable evidence package.