August 11, 2026 · Comparison

Modbus Poll vs Modscan vs Modbus Slave: Which Master Tool to Use

By Dzulfikar Ats Tsauri, founder of Voltrus / JoyoDigitama. He builds the protocol tools covered in these posts. Updated October 28, 2026.

You need to read holding register 40001 from a power meter, or write a setpoint to a VFD, and you need a Modbus master tool to do it. Search for one and the same three names come up everywhere: Modbus Poll, Modscan, and a handful of Modbus Slave simulators. The names are confusingly similar, the screenshots look interchangeable, and nobody explains which one you actually want.

This guide compares the three on the dimensions that matter: what platform they run on, whether they do TCP and RTU, whether they can only poll or also simulate a slave, and what they cost. If you want the deeper protocol background first, see our Modbus protocol primer or the function code reference.

The Three Tools, in One Sentence Each

• Modbus Poll (Witte Software), a widely used Windows Modbus master. Multiple-document interface, paid perpetual license, 10-minute-per-connection demo. Windows only (x64, ARM64, x86 builds).
• ModScan32 / ModScan64 (WinTECH Software), a long-running Windows Modbus master. Functional for quick reads and test scripts, but the UI is dated. The WinTECH download page lists ModScan32 8.A00-10 (March 2014) and ModScan64 2.A00-00 (November 2017) as the latest builds. Paid, with a time-limited demo.
• Modbus Slave (Witte Software), the companion to Modbus Poll. Same vendor, same look, runs as a slave/server simulator so a master has something to talk to. Windows only.

Notice the pattern: every one of these is a Windows application. If you are on macOS or Linux, none of them runs natively. That single fact drives most of the "which tool should I use" decisions in the field. More on the Mac gap below.

Feature Comparison

Modbus Poll (Witte Software)

The reference implementation most engineers mean when they say "Modbus Poll." It opens multiple windows (one per slave connection) and lays out register data in a spreadsheet grid. You specify the slave ID, function, address, size, and poll rate per window. Double-click a value to write it: single registers and coils use FC06 and FC05, and writing several at once uses FC16 or FC15. The demo disconnects after 10 minutes per connection, and a license is $129 for one to two users, perpetual, per the Witte order page.

Its weakness is the same as every other tool in this list: it is Windows software. On macOS you run it through Parallels or a Windows VM, which is a heavy lift for a register-read utility. For the mechanics of reading registers, see our holding-register walkthrough.

Modscan / Modscan32

ModScan is the older of the two. Per the WinTECH product page, ModScan32 supports serial connections, modem (TAPI) connections and Modbus/TCP, in both RTU and ASCII modes, with debug mode for the raw serial data and test scripts for production testing. It is a master only; WinTECH sells ModSim as the separate simulator. The latest builds listed on the vendor's download page date from 2014 (ModScan32) and 2017 (ModScan64), so check that your PC and adapter driver combination works with the demo before you buy.

Modbus Slave (the simulator half)

"Modbus Slave" means two things and people conflate them. The first is Witte Software's companion app to Modbus Poll, a slave simulator from the same vendor (version 10.0.0 on the Witte download page, $129 per license on the order page). The second is the general concept of a slave/server simulator. You need a simulator when the real device is not on your bench: you stand up a virtual power meter, point your master at it, and confirm your register map and scaling before you ever touch the field hardware.

The macOS Gap

All three legacy options assume Windows. If your laptop is a Mac, your choices are a Windows virtual machine such as Parallels, a Remote Desktop session into a Windows machine, or a native Mac app.

MacTools Modbus Poll closes that gap. It is a native macOS app that does TCP and RTU, runs as a master and a slave simulator, and ships with real device templates: a Schneider PM5560 power meter, an SMA solar inverter, and an ABB analyzer, so you can test against a realistic register map instead of a flat block of zeros. See the simulator comparison for the full device list.

Further Reading

• Best Modbus Simulator in 2026: Free and Paid Tools Compared
• How to Read Modbus Holding Registers (FC03): A Practical Walkthrough
• How to Write Modbus Registers: FC06, FC16, and Coils
• Modbus Function Codes Explained: FC01–FC06, FC15, FC16