# Learn Modbus

> A sixteen-module, source-grounded Modbus course for integrators. Covers the message model, addressing, data types, RS-485, Modbus TCP, gateways, troubleshooting, and a real-device capstone.

Content version: 1.0.0
Access: free-public (no paid content boundary in this app)

## Modules
- [Module 1: What Modbus Is](https://learnmodbus.studioseventeen.io/api/public/md/what-modbus-is) [Published]: The mental model, why Modbus is still everywhere, and what it deliberately does not give you.
- [Module 2: The Message Model](https://learnmodbus.studioseventeen.io/api/public/md/message-model) [Published]: PDU vs ADU, how requests, responses, and exceptions actually look on the wire.
- [Module 3: Data Tables](https://learnmodbus.studioseventeen.io/api/public/md/data-tables) [Published]: Coils, discrete inputs, input registers, and holding registers — the four primitives.
- [Module 4: Function Codes](https://learnmodbus.studioseventeen.io/api/public/md/function-codes) [Published]: Reads, writes, diagnostics, and the codes you'll actually meet in the field.
- [Module 5: Modbus Addressing](https://learnmodbus.studioseventeen.io/api/public/md/modbus-addressing) [Published]: 0-based wire addresses vs 1-based documentation, and how off-by-one bugs are born.
- [Module 6: Register Maps](https://learnmodbus.studioseventeen.io/api/public/md/register-maps) [Published]: Reading a vendor map and turning it into a reliable, reviewed integration plan.
- [Module 7: Data Types](https://learnmodbus.studioseventeen.io/api/public/md/data-types) [Published]: INT16, UINT16, INT32, FLOAT, word/byte order, and the encoding traps you'll hit.
- [Module 8: Scaling & Engineering Meaning](https://learnmodbus.studioseventeen.io/api/public/md/scaling-engineering-meaning) [Published]: Raw register → engineering value with units, scale, and a sanity check at every step.
- [Module 9: Serial Communication Basics](https://learnmodbus.studioseventeen.io/api/public/md/serial-communication-basics) [Published]: Baud, parity, stop bits, timing — the fundamentals every RTU integrator must own.
- [Module 10: RS-232, RS-422, RS-485](https://learnmodbus.studioseventeen.io/api/public/md/rs-physical-layers) [Published]: Topologies, biasing, termination, and why your bus quietly stops working at node 17.
- [Module 11: RTU & ASCII Frames](https://learnmodbus.studioseventeen.io/api/public/md/rtu-ascii-frames) [Published]: Frame structure, CRC vs LRC, silent intervals, and reading captures by hand.
- [Module 12: Modbus TCP](https://learnmodbus.studioseventeen.io/api/public/md/modbus-tcp) [Published]: MBAP, unit identifiers, ports, and what changes (and doesn't) moving from RTU.
- [Module 13: Gateways & Mixed Networks](https://learnmodbus.studioseventeen.io/api/public/md/gateways-mixed-networks) [Published]: TCP↔RTU routing, unit IDs, latency, and how to keep mixed deployments diagnosable.
- [Module 14: Troubleshooting Workflow](https://learnmodbus.studioseventeen.io/api/public/md/troubleshooting-workflow) [Published]: A repeatable evidence-first method for diagnosing failed reads, writes, and timeouts.
- [Module 15: Security & Safety](https://learnmodbus.studioseventeen.io/api/public/md/security-safety) [Published]: What classic Modbus does not protect, write safety practice, and TLS / Modbus Security.
- [Module 16: Capstone: Real Device Integration](https://learnmodbus.studioseventeen.io/api/public/md/capstone-real-device-integration) [Published]: Bring a real or simulated device online with a reviewable evidence package.

## Full course
- [Full course markdown](https://learnmodbus.studioseventeen.io/api/public/md/full-course): All modules in one file.
- [llms-full.txt](https://learnmodbus.studioseventeen.io/llms-full.txt): Complete lesson, diagram, lab, and quiz text.