Modbus TCP Tester & Diagnostic Tool
The fastest, most reliable Modbus TCP testing software for automation engineers, SCADA developers, and commissioning technicians. Test Modbus TCP/IP servers, simulate PLC data, and monitor raw communication packets on Windows 10/11.
Instant setup • No credit card required • Native 64-bit Windows performance
Complete Modbus TCP Testing Capabilities
Everything you need to diagnose, stress-test, and validate Modbus TCP industrial equipment.
Multi-Connection Modbus Master
Connect to multiple Modbus TCP slave devices simultaneously across different IP addresses and subnets. Monitor live telemetry and poll cycles in real time.
Full Function Code Support
Supports Read Coils (FC01), Discrete Inputs (FC02), Holding Registers (FC03), Input Registers (FC04), Write Single (FC05/FC06), and Write Multiple (FC15/FC16).
Packet Traffic Sniffer & Logger
Inspect raw MBAP headers, transaction IDs, unit identifiers, and PDU payloads in Hex and ASCII formats. Isolate CRC and framing errors instantly.
Data Formatting & Endianness
Display registers as 16-bit Int, 32-bit Float (ABCD, CDAB, BADC, DCBA), Double, 64-bit Int, Binary bitfields, and ASCII strings with one-click conversion.
High-Speed Polling & Stress Tests
Configure custom scan intervals down to 10ms. Run automated load testing to verify PLC response times and network latency under high traffic.
Server (Slave) Emulation
Don't have physical hardware? Run ModbusSimulator as an active Modbus TCP server on Port 502 to test SCADA, Ignition, Wonderware, and IoT gateways.
ModbusSimulator vs Legacy Modbus Test Tools
Why modern engineering teams choose ModbusSimulator over outdated 32-bit utilities.
| Feature / Capability | ModbusSimulator | Modbus Poll | ModRSsim2 | DiagSlave |
|---|---|---|---|---|
| Modbus TCP + RTU | Yes (Unified) | Yes (Separate License) | Limited | CLI only |
| Master & Slave in One App | Yes | Separate App Required | Slave only | Slave only |
| Modern Windows 10/11 UI | Native 64-bit High-DPI | Legacy Win32 | Legacy Win95/XP Style | Command Line Only |
| Built-in SCADA & HMI Dashboard | Yes (Gauges, Trends) | No | No | No |
| Pricing & Licensing | Affordable Lifetime / Subscription | $129+ per seat | Outdated Open Source | Discontinued CLI |
How to Test Modbus TCP in 3 Simple Steps
Get up and running in under 2 minutes with ModbusSimulator.
Download & Launch
Download ModbusSimulator on Windows. No complicated drivers or prerequisites required.
Configure IP & Port 502
Select Modbus TCP Master mode, enter the target IP address, Port 502, and your slave Unit ID.
Poll & Inspect Registers
Click Connect. View real-time register values, raw request/response frames, and latency stats instantly.
Frequently Asked Questions
What is the difference between Modbus TCP and Modbus RTU testing?
Modbus TCP operates over Ethernet networks using IP addresses and standard TCP Port 502 with a 7-byte MBAP header. Modbus RTU operates over serial RS-485/RS-232 connections using baud rates, parity, and CRC-16 checksums. ModbusSimulator supports testing both protocols seamlessly.
Why is my Modbus TCP connection timing out?
Common causes include Windows Firewall blocking inbound/outbound Port 502, incorrect IP subnet configuration, mismatched Unit IDs, or the target PLC reaching its maximum allowed concurrent socket connections.
Can I test Modbus TCP over Wi-Fi?
Yes, as long as your computer is on the same local network subnet or has routing access to the target Modbus TCP device, testing works over Wi-Fi, Ethernet, and VPN connections.