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Modbus Poll Alternative: WIMNET Modbus Scanner

A free Windows Modbus master — poll, scan slave IDs, decode byte order.

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You have a meter, a drive or a PLC on the bench, an RS-485 pair or an IP address, and a register map you only half trust. WIMNET Modbus Scanner is a free Windows Modbus master built for exactly that moment: poll over TCP or RTU, find the slave ID, sweep the address range, decode the byte order, and watch the raw bytes go past with their timing.

It is written by the engineering team at Wiman — an industrial IoT hardware manufacturer in Chennai — because those are the things we do on our own bench every day.

What you get by building it here

Free, and downloadable without a purchase orderThere is no licence fee, no purchase order, no forex payment and no approval chain between you and a device that is refusing to answer — you download it and you run it. Take the Windows build from our Resources page, or open the animated walkthrough first if you want to see the layout before you install anything. For the job behind a lot of the 'free Modbus master software' searching — confirm a device is alive, find its ID, read a handful of holding registers — that is the entire workflow.
The jobs a bus bring-up actually needs, in one windowPoll (Modbus master over TCP and RTU), Device Scan (discover slave IDs on the bus), Register Scan (sweep address ranges for live data), Byte-Swap Decode (ABCD / BADC / CDAB / DCBA side by side) and Traffic (raw RX/TX packet hex with timing). Those five are the published feature list, and the order is close to the order a stubborn bus gets debugged in: is anyone there, who are they, where is the data, how should it be read, and what is actually on the wire.
Byte order shown four ways at the same timeByte-Swap Decode puts ABCD, BADC, CDAB and DCBA side by side, so a 32-bit float or long is read four ways at once and you pick the column that is obviously right. Register-pair and byte order is where a great deal of Modbus integration time disappears, particularly with energy meters and inverters. To be clear, byte-order handling is not something only we do — Modbus Poll, for one, offers 28 display formats including word-order swapping. This is how ours presents it, not a gap in theirs. If you are working from someone else's captured hex rather than a live device, our browser Modbus Hex Converter does the same four decodes, verifies CRC-16, and encodes values back to register bytes.
Raw RX/TX hex with timing, not only the decoded valueThe Traffic view shows the packets as bytes with their timing. Many real Modbus faults are not value problems at all — they are silent-interval, no-reply, half-duplex turnaround, mis-set parity or CRC problems, and those live in the gap between frames rather than in a decoded register. If the traffic view shows nothing at all, the fault is usually wiring or termination, which is what our RS-485 guide covers.
Support in IST, from the people who design the hardwareWiman designs and manufactures industrial gateways, protocol converters and RS-485 IO modules in Chennai. If the device at the other end of the bus is one of ours, the engineer replying to you can pull up the register map, and we aim to come back to you within the same working day, in your time zone. On the hardware side that also means quoting in INR against a GST invoice, with stock and service handled domestically rather than through an import and customs step.
OEM, white-label and firmware customisation are ordinary requests hereIf you ship hardware and want a scanner carrying your name and your defaults in the box, or a gateway with firmware behaviour changed for your application, that is a conversation with an engineer. We are a manufacturer, so low-volume OEM builds and firmware changes are routine work here rather than an exception. Tell us what you are building and we will tell you plainly whether it is a fit.

Our published specifications

Every figure below is our own, taken from the product datasheet. We do not publish competitor specifications here — check theirs against their current datasheet and compare directly.

ItemWimanNotes
ToolWIMNET Modbus ScannerFree utility published by the Wiman engineering team on our Resources page
RoleModbus master (client)It polls devices; it is not a slave/server simulator
TransportsModbus TCP and Modbus RTUEthernet/IP devices and RS-485 serial buses
PlatformWindowsDesktop application
PollModbus master over TCP & RTURead live values from a device
Device ScanDiscover slave IDs on the busFor when the slave address is unknown or the documentation is wrong
Register ScanSweep address ranges for live dataRebuild a usable map when you were not given one
Byte-Swap DecodeABCD / BADC / CDAB / DCBA side by sideAll four interpretations at once, in one view
Traffic viewRaw RX / TX packet hex with timingSee the bytes and the gaps between them
Browser walkthroughAnimated walkthrough at /tools/wimnet-scanner-demo.htmlA guided tour of the interface that plays in the browser, so you can see how the tool works before installing. It does not connect to a device — actual polling needs the Windows build.
DownloadWindows build from the Resources pageThe download link is rebuilt daily, so take a fresh one from the site rather than bookmarking the file
PriceFreeNo purchase order, no forex, no approval cycle
Companion free toolModbus Hex Converter — Int, UInt and Float in ABCD / BADC / CDAB / DCBA, CRC-16 verify, encode back to register bytesBrowser tool, no install
Also on the tools pageModbus Simulator — multi-slave Modbus TCP / RTUListed as Coming Soon; not released yet, so do not plan around it
SupportDirect from our engineering team in Chennai (IST)The same people who design our gateways, converters and IO modules

When Modbus Poll (Witte Software) is the better choice

Be honest about this before you download anything: Modbus Poll from Witte Software is a serious piece of protocol tooling. Its copyright runs from 2002 and the vendor describes it as a proven product trusted by customers for over twenty years — for protocol tooling that longevity is real engineering value, because the awkward edge cases were found by other people years ago.

It is sold as a perpetual licence with free unlimited support and maintenance upgrades, and a single-user licence may be used on several computers by that one person, so a laptop, a bench PC and a site machine are covered by one purchase. Over a career that is excellent value, and it compares very favourably with subscription tooling.

You can also try it before buying: the vendor publishes a time-limited evaluation download, and the current evaluation terms are set out on their own site. On capability it covers a great deal that our scanner does not touch at all. It supports eight protocol variants, including the awkward-but-common encapsulated forms — RTU over TCP/IP, ASCII over TCP/IP and the UDP variants — and function codes 01 to 43, so an unusual encapsulation or an uncommon function code is very likely already handled.

It offers 28 display formats including word-order swapping, so if you were weighing us up on byte-order handling alone, that is not a gap on their side. It has OLE Automation for Excel via VBA macros and ships an example spreadsheet, which is a genuinely powerful workflow if your commissioning sheets and acceptance tests live in spreadsheets.

It has a multiple-document interface for polling and watching several slaves and data areas at once, which matters on a multi-drop bus; a Test Center for hand-composing raw test strings; Address Scan; serial traffic monitoring; text-file logging and direct Excel export; real-time charting; conditional colour selection; and an RTS toggle for RS-485 converters.

Those are the features of a tool built by people who debug buses for a living. And because it comes from a small vendor answering its own support email, the person who replies to you is quite likely the person who wrote the code — that is a real advantage a larger organisation cannot always offer. WIMNET Modbus Scanner does none of the Excel or OLE automation, no charting, no multi-window work, none of the encapsulated or UDP transports, and it does not simulate a slave.

If any of that is your daily workflow, buy theirs and use it for the next ten years. Three other honest cases. Simply Modbus sells a site licence covering unlimited users at one location, which is the sensible route for a plant or a training lab equipping many seats rather than one engineer. If you are on Linux, want auditable source, or need the test scripted into CI, then QModMaster — free, open source, with Windows and Linux builds and a bus monitor — or the free command-line modpoll utility are the right tools and ours is not, because ours is a Windows application.

And a general-purpose protocol tool is deliberately device-agnostic: that is a strength, not a gap, when your bench has a dozen vendors on it. Collectively these tools are how a whole generation of engineers learned Modbus, and that is worth saying plainly rather than arguing around. One note on pricing: we have deliberately quoted no prices for anyone on this page, including our competitors.

Prices change, and a stale figure presented as current is simply a false statement. Check each vendor's own order page for current pricing and licence terms.

Questions we get asked

Is WIMNET Modbus Scanner actually free?

Yes. It is one of the free utilities our engineering team publishes on the Resources page, alongside the Modbus Hex Converter, the 4-20 mA Loop Explorer and the IoT SIM Data Calculator. There is an animated walkthrough you can open in a browser to see the interface before installing anything — it is a guided tour, not a working master, so any actual polling needs the Windows build.

Why does the download link change every day?

The download button builds a dated link, so yesterday's link stops working. That is deliberate — it stops stale copies of the URL circulating, so people come back to the Resources page for a current link rather than passing a file around. Take a fresh link from the Resources page each time rather than bookmarking the .exe URL.

Does it work with other manufacturers' devices, or only Wiman hardware?

Any Modbus device. It is a standard Modbus master over TCP and RTU with nothing keyed to our own products — energy meters, VFDs, PLCs, transmitters, flow computers, other vendors' gateways. If it speaks Modbus, the scanner polls it.

I do not know the slave ID, and the register map I was given does not match reality.

That is what Device Scan and Register Scan exist for. Device Scan walks the bus looking for slave IDs that answer; Register Scan sweeps an address range and shows what actually comes back live, so you can rebuild a working map from the device itself. If nothing answers at all, suspect the bus before the map — start with the RS-485 wiring guide, then the Modbus RTU primer.

My 32-bit float reads a nonsense number like 3.4e-38.

Almost always register/byte order rather than a broken device. Byte-Swap Decode shows ABCD, BADC, CDAB and DCBA at the same time, so you simply pick the column that reads 415.2. If you are working from hex someone captured in a log rather than a live device, the browser Modbus Hex Converter does the same four decodes and verifies CRC-16.

Does it run on Linux or macOS?

No — it is a Windows application, and we will not pretend otherwise. If your workstation is Linux, or the test has to run headless inside a script or CI job, QModMaster (free, open source, Windows and Linux builds, with a bus monitor) or the free command-line modpoll utility are the usual choices and they are good ones.

Can it act as a Modbus slave or server for testing the other direction?

Not today. WIMNET Modbus Scanner is a master only. A separate multi-slave Modbus TCP/RTU simulator is listed as Coming Soon on our tools page, and until it ships you will need a dedicated slave simulator — Modbus Slave from Witte Software is a long-established option, and is a separate product from Modbus Poll.

Are you affiliated with Witte Software or any of the other tools named here?

No. Wiman has no affiliation, partnership, endorsement, distribution or certification relationship with Witte Software or with any other vendor named on this page, and nothing here is authorised, reviewed or approved by them. Modbus Poll and Modbus Slave are trademarks of Witte Software; QModMaster, Simply Modbus and modpoll belong to their respective owners; Modbus is a registered trademark of Schneider Electric. We use these names only to identify products engineers compare against, which is the sole reason they appear here. Anything you want to know about their features, prices or licence terms should come from their own sites — we have deliberately quoted no prices, because prices change and a stale one would be misleading.

We are an OEM. Can we get this with our own branding, or a gateway with changed firmware?

Talk to us. We design and build gateways, protocol converters and RS-485 IO modules in Chennai, so white-labelled tooling, firmware customisation and low-volume OEM builds are ordinary work here rather than special projects. On the hardware side that also means quoting in INR against a GST invoice, with stock and service handled domestically.

Where to go next

Tell us the site, the protocol and the quantity — we will tell you honestly whether we fit.Send an enquiry →

Modbus Poll is a trademark of Witte Software. All trademarks are the property of their respective owners. Wiman is not affiliated with, endorsed by or sponsored by Modbus Poll (Witte Software). Comparisons describe our own products only; verify any third-party product against its current published datasheet before purchase.