Modbus
23 articles tagged "Modbus" on the Modbus Poll blog.
This collection brings together every Modbus article published on the Modbus Poll blog. "Modbus Poll vs Modscan vs Modbus Slave: Which Master Tool to Use", "Modbus TCP vs PROFINET: Choosing the Right Industrial Ethernet", "How to Read Modbus Holding Registers (FC03): A Practical Walkthrough" — each one is a practical, hands-on guide written for engineers and system integrators who work with Modbus Poll in real industrial deployments. Whether you are choosing between protocols, troubleshooting a connection, or planning an integration, these articles cover the concepts, the trade-offs, and the step-by-step details you need.
Modbus Poll vs Modscan vs Modbus Slave: Which Master Tool to Use
Modbus Poll, Modscan, and Modbus Slave compared. Platform support, RTU vs TCP, master and simulator modes, pricing, and which Modbus master tool fits your workflow in 2026.
Read articleModbus TCP vs PROFINET: Choosing the Right Industrial Ethernet
Modbus TCP vs PROFINET compared. Real-time determinism, device discovery, configuration effort, vendor ecosystem, and when to use each industrial Ethernet protocol.
Read articleHow to Read Modbus Holding Registers (FC03): A Practical Walkthrough
How to read Modbus holding registers with function code 03. Slave ID, start address, quantity, the FC03 frame, 16-bit byte order, and 32-bit scaling explained.
Read articleHow to Write Modbus Registers: FC06, FC16, and Coils FC05/FC15
How to write Modbus registers and coils. FC06 write single register, FC16 write multiple, FC05/FC15 coils. Frame layout, exception codes, and safe write practice.
Read articleModbus RTU to TCP Gateway: Bridge Serial Devices onto Ethernet
Modbus RTU to TCP gateway explained. Why bridge RS-485 serial devices onto Ethernet, how a gateway routes TCP requests to RTU slaves, latency, hardware vs software gateways.
Read articleModbus 32-Bit Integer Data Types: Registers, Byte Order, and Scaling Explained
How Modbus handles 32-bit integers: two registers per value, word order (high word first vs low word first), signed vs unsigned, register pairs, and scaling examples for energy meters and drives.
Read articleModbus Function Codes Explained: FC01–FC06, FC15, FC16 (2026 Reference)
Every standard Modbus function code explained: FC01 read coils, FC03 read holding registers, FC06 write single register, FC16 write multiple. Request/response frame layout, byte order, and when to use each code.
Read articleModbus Addressing Explained: PLC Address vs Protocol Address (No More Off-By-One)
Why Modbus holding register 40001 is protocol address 0. The PLC address vs protocol address off-by-one confusion, the four address ranges, and how to convert between them.
Read articleModbus Exception Codes Explained: Illegal Function, Data, Address (2026 Troubleshooting)
Modbus exception codes 01–08 decoded: Illegal Function, Illegal Data Address, Illegal Data Value, Slave Device Failure. What each exception means, why your master gets it, and how to fix the request.
Read articleModbus Float Byte Order Explained: ABCD, DCBA, BADC, CDAB
A 32-bit Modbus float spans two registers and every vendor picks a different byte order. Why your 230 V reading shows as 0.003, and how to cycle the four conventions to fix it.
Read articleModbus TCP Security Risks: Why It Is Not Safe and How to Protect It
Modbus TCP has no authentication, encryption, or integrity — anyone on the network can read and write every register. Segment, firewall, and tunnel it; never expose TCP/502.
Read articleBest Modbus Simulator in 2026: Free and Paid Tools Compared
Need to test Modbus devices without hardware? Compare 7 Modbus simulators: Modbus Poll, Modbus Slave, diagslave, and more. Covers macOS, Windows, Linux. Free download links included.
Read articleModbus Poll Tool: How to Read and Write Registers on macOS (2026)
A complete guide to Modbus poll tools: what they do, how they work, function codes FC01-FC06, and how to read/write Modbus registers on macOS with a native poll tool. TCP + RTU support.
Read articleModbus RTU Troubleshooting Guide: CRC Errors, Timeouts, and Wiring
Fix Modbus RTU communication errors. Step-by-step troubleshooting for CRC errors, timeouts, and wiring problems. How to read Modbus RTU frames and diagnose RS485 bus issues.
Read articleModbus TCP Tool for macOS: Test and Debug Devices Without Windows (2026)
Need a Modbus TCP tool on macOS? MacTools Modbus Poll is a native Mac app for testing and debugging Modbus TCP devices. Read/write registers, simulate slaves, verify register maps.
Read articleWhat Is Modbus? The Protocol That Runs Industrial Automation
Modbus explained for engineers: how it works, why it's still dominant after 50 years, and the difference between Modbus RTU, TCP, and ASCII.
Read articleModbus RTU vs TCP: Which Variant Should You Use?
Modbus RTU and Modbus TCP use the same protocol but different transports. Frame format, speed, device limits, and when to choose each variant.
Read articleModbus Register Types Explained: Coils, Discrete Inputs, Holding Registers, Input Registers
The four Modbus data types and their function codes. How to read coils (FC01), write registers (FC06/FC16), and avoid common addressing mistakes.
Read articleModbus Poll for macOS: A Native Alternative That Actually Works
Looking for Modbus Poll on macOS? MacTools Modbus Poll is a native Mac app for reading and writing Modbus TCP and RTU registers. Master + slave simulator with device templates. $29.99 one-time.
Read articleBest Modbus Simulator for macOS (2026): PM5560, SMA Inverter, and More
Modbus simulator with real device templates. Simulate Schneider PM5560 power meter, SMA solar inverter, ABB analyzer on macOS. No Parallels, no Windows.
Read articleSchneider PM5560 Modbus Register Map and Simulator
Complete PM5560 Modbus register map with addresses for voltage, current, power, power factor, frequency, and energy. Includes a PM5560 simulator for macOS.
Read articleModbus TCP vs OPC-UA: What System Integrators Actually Need to Know
Modbus is simple. OPC-UA is complex. Here is the honest comparison: when each makes sense, and why the middleware gap matters.
Read articleHow to Monitor Modbus TCP Devices Without the Middleware Bloat
The typical integrator stack — MQTT broker, flow engine, time-series DB, visualization layer — eats 2 to 4 GB RAM before you add your application. There is a simpler way.
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