Complete reference and tutorial guides for Modbus RTU and Modbus TCP — function codes, register types, RS-485 wiring, data types, byte order, exception codes, SCADA integration, troubleshooting, and security for industrial automation.
View Our SCADA & Programming ServicesModbus is an industrial communication protocol developed by Modicon in 1979 that uses a master/slave request-response model to exchange data between devices. It is available …
Modbus is a master/slave industrial communication protocol developed by Modicon in 1979. Available as RTU (serial), ASCII, and TCP (Ethernet), it is the most widely …
Modbus RTU uses serial RS-485 with binary encoding and CRC. Modbus TCP uses Ethernet on port 502 with the same data model. Both use identical …
Complete reference for Modbus function codes FC01 through FC16 — what each reads or writes, request/response frame structure, and which are most commonly used.
The four Modbus register types: coils (1-bit R/W), discrete inputs (1-bit RO), input registers (16-bit RO), and holding registers (16-bit R/W) with address ranges and …
How to wire a Modbus RTU RS-485 network — cable selection, daisy-chain topology, termination resistors, bias resistors, shielding, max distance, and common mistakes.
How to set up a Modbus TCP network — IP addressing, TCP port 502, firewall rules, multi-master access, VLAN segmentation, and gateway devices.
How Modbus master/slave communication works — request-response cycle, polling design, timeouts, retry logic, and gateway/concentrator architectures.
How to handle 32-bit integers, IEEE 754 floats, and strings in Modbus registers — byte order (endianness) variations and how to determine the correct order.
What Modbus exception codes mean, how to identify them in frames, and how to diagnose and resolve each exception type.
How to configure Modbus TCP and RTU device connections in Ignition SCADA — driver setup, tag addressing, data types, byte order, and troubleshooting.
How to configure Modbus RTU and TCP device connections in Geo SCADA Expert — channel setup, device addressing, point configuration, and register mapping.
Security limitations of Modbus, common attack vectors, and practical controls — network segmentation, firewalls, deep packet inspection, and the emerging Modbus Secure standard.
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