Recommended ModulesLink Products
Use modpoll to automate testing and commissioning of these industrial communication modules
RS-485 Transceiver
- Up to 5000VDC isolation
- ESD protection ±8kV
- 256 nodes on bus
- -40°C to +105°C
CAN Transceiver
- Up to 5000VDC isolation
- CAN 2.0A/2.0B protocol
- ESD ±8kV, Surge ±4kV
- -40°C to +105°C
Digital Isolators
- Up to 5000VDC isolation
- CMTI >100kV/µs
- Data rate 150Mbps
- -40°C to +125°C
Version
3.16
File Size
206 KB (ZIP)
Platform
Windows / Linux
Type
CLI (Command Line)
Overview
modpoll is a lightweight command-line Modbus master tool that supports all three Modbus transport protocols: RTU (serial), TCP (Ethernet) and UDP. Its small footprint (under 200KB) and command-line interface make it the ideal choice for automated testing, batch processing, and integration into scripts and CI/CD pipelines.
Unlike GUI-based tools, modpoll can be called from batch files, shell scripts, Python programs, or any automation framework. The tool returns meaningful exit codes, making it easy to build reliable automated test sequences.
Key Features
⚙ RTU / TCP / UDP
Full support for all three Modbus transport protocols. Switch between serial RTU and Ethernet TCP/UDP with a single command flag.
📦 Ultra Lightweight
Under 200KB executable. No installation, no dependencies, no runtime. Just extract and run on any Windows or Linux system.
💻 Scriptable
Designed for automation. Call from batch files, shell scripts, Python, or any language. Exit codes indicate success or failure.
🔎 All Function Codes
Supports FC01-06 and FC15-16 for reading/writing coils, discrete inputs, holding registers and input registers.
Command Reference
Basic Syntax
Common Options
modpoll Command-Line Options
| Flag | Description | Example |
|---|---|---|
-m | Protocol mode: rtu, tcp, udp | -m rtu |
-a | Slave address (1-247) | -a 1 |
-r | Start register address | -r 100 |
-c | Number of registers to read | -c 10 |
-b | Baud rate (RTU only) | -b 9600 |
-p | Parity: none, even, odd (RTU) | -p even |
-t | Data type: 3=holding, 4=input, 1=coil, 2=discrete | -t 3 |
-1 | Single poll mode (exit after one read) | -1 |
Automation Examples
Batch File (Windows)
Shell Script (Linux)
Compatible with ModulesLink Products
Use modpoll in your commissioning scripts to verify ModulesLink Modbus gateways are responding correctly. Combine with diagslave to create automated test loops that validate both master and slave communication paths.