Modbus tutorials

Each tutorial has goals, prerequisites, numbered steps with expected results, common errors and a cleanup. Every command and result comes from real runs of the PDComm Modbus SDK and simulators. Check the background pages listed at the top of each tutorial before you start.

Order	Tutorial	What you get	What you need
1	Observe addresses and frames	Manual address conversion, bit packing, exceptions, TCP/RTU/ASCII frames and CRC/LRC errors	Headless simulator
2	A closer look at the first TCP exchange	SDK layout, API ownership and threading rules, lost connections	C++ or C# console
3	The 19 function codes and diagnostics	Every function code, diagnostics sub-functions, listen-only mode, broadcasts	Headless simulator
4	RTU and ASCII communication	Serial configuration, raw frames, CRC fault injection, real devices	Virtual serial ports
5	TCP-to-serial gateway	Unit route table, exceptions 0A and 0B	Virtual serial ports
6	Modbus/TCP Security	Role certificates, per-role permissions, TLS failures, CRLs	OpenSSL 3
7	Build a test workflow with the simulators	GUI server, projects, scenario regression tests, MCP	GUI simulator, jq
8	Diagnose failures and report them	Failing-layer triage, diagnostic log analysis, support request	C++ console, jq

If you’re new, finish the quickstart, then do 1, 2 and 3 in order. Continue with 4 and 5 for serial devices and with 6 for secure connections.

The commands are written for macOS and Linux shells. On Windows, programs and libraries end in .exe and .dll, and you set environment variables in PowerShell’s $env: form.