Modbus Guides & Resources
Everything engineers need to work with Modbus — protocol references, wiring guides, troubleshooting, and practical tutorials using ModPackQT.
Modbus Protocol Overview
What is Modbus, how it works, history, and why it dominates industrial automation.
Modbus RTU Wiring & Setup
RS-485 bus topology, baud rates, termination resistors, CRC-16, and serial port configuration.
PC Network Setup for Modbus TCP
Set a static IP address, subnet mask, and gateway on Windows, Mac, and Linux. Test with ping and open firewall port 502.
Modbus TCP/IP Configuration
Ethernet networking, port 502, MBAP header, connection pools, firewall rules, and TCP clients.
Registers, Addressing & Data Formats
The four register types, 0-based vs 1-based addressing, 32-bit floats, byte order, and scaling.
Modbus Function Codes Reference
FC01–FC16 read/write commands, request/response structure, exception frames, and max quantities.
Modbus Troubleshooting & Error Codes
Exception codes, CRC mismatch causes, timeout strategies, RS-485 grounding, and common integration mistakes.
Modbus Master Software Guide
Polling strategies, register grouping, auto-poll, data logging, and a ModPackQT demo walkthrough.
Modbus Master Simulator
Simulate a Modbus master polling slaves and PLCs — FC01–FC23, auto-poll, exception handling, and timing controls.
Modbus Slave Simulator
Simulate PLCs, sensors, and meters in software — sine, ramp, and step waveforms for realistic test data.
Modbus PLC Integration
Connect industrial PLCs via Modbus — data mapping, register configuration, and SCADA integration.
Modbus Energy Meter Setup
Read kWh, power, current, and voltage from RS-485 and Ethernet Modbus energy meters.
Tutorial Videos
Watch walkthroughs, demos, and Modbus tutorials on our YouTube channel.
Modbus Glossary
90 Modbus terms defined in plain English — function codes, register types, data types, byte order, and exceptions.
RS-485 Wiring Guide
Step-by-step RS-485 bus wiring for Modbus RTU — termination resistors, bias resistors, cable selection, topology, and troubleshooting.
Modbus vs BACnet
Side-by-side comparison of Modbus and BACnet — strengths, use cases, and how to decide which protocol fits your project.
Interactive Modbus Tutorial
13 hands-on lessons covering Master, Slave, and protocol internals. Fire real Modbus requests at a virtual slave — no hardware needed.
Virtual Modbus Devices API
REST API for solar inverters, batteries, and energy meters. 6 RapidAPI products with 30 virtual devices — read live data and write control setpoints.
User Manual
Complete PDF guide to ModPackQT — gateway setup, connection profiles, Modbus master & slave, advanced function codes FC8/FC23/FC43, and data type reference.
Node-RED Integration Guide
Install node-red-contrib-modbus-modpackqt — self-contained Modbus TCP/RTU master and embedded slave server, plus live commissioning probes that pair with the modpackqt.com web console. All 8 nodes are 100% free.
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