What you actually get with the Modbus Poll free download
When engineers search "Modbus Poll free download," most are expecting a no-cost tool they can keep using indefinitely. In practice, the free download installs a fully-featured 30-day trial. During that window you can poll registers, read live values, and validate master-side communication against a real or simulated device.
Once the 30 days run out, the trial stops working and you need to buy a license to continue. That's a normal trial model, but it catches people off guard if they were expecting a permanently free utility.
The part most "free download" searches miss
Modbus Poll only handles the master/polling side of testing. If your project also needs a slave device to poll against — which most PLC, SCADA, and HMI testing workflows do — that's a separate product (Modbus Slave), with its own license. So the free download alone doesn't give you a complete master-and-slave testing setup, even during the trial period.
Modbus Poll Free Download vs a Free Alternative
| Feature | Modbus Poll (free download) | ModbusSimulator (free download) |
|---|---|---|
| Trial length | 30 days | 30 days |
| Master/polling mode | Included | Included |
| Slave simulation | Separate paid product ($129) | Included in the same download |
| Cost after trial (both modes) | $258 (master + slave combined) | $99 one-time |
| License model | Per-tool license | Single one-time license |
Who the free trial is good enough for
- Quick evaluation of Modbus master/polling behavior
- Short-term projects that fit inside the 30-day window
- Teams that already own Modbus Slave separately
When you'll want more than the free download offers
If you need to keep testing past 30 days, or you need both master and slave modes without buying two separate tools, it's worth trying a simulator that bundles both from the same free download. That way the free trial period actually reflects the full workflow you'll use day to day, master and slave included, instead of testing one half now and pricing out a second tool later.
Related pages
Want a free download with master + slave included?
Try ModbusSimulator free for 30 days — polling and slave simulation in one download, then a $99 one-time license instead of $258.
Download Free TrialFAQ
Is Modbus Poll actually free to download?
The download itself is free, but the software is a 30-day evaluation. After the trial period ends, Modbus Poll requires a paid license to keep using it — it is not a permanent free tool.
What is limited in the Modbus Poll free trial?
The trial runs full-featured for 30 days, but it also only covers master/polling mode. Slave simulation is a separate paid product (Modbus Slave), so the free download does not include a full master-and-slave testing workflow.
Is there a genuinely free alternative to Modbus Poll?
Yes. ModbusSimulator offers a free 30-day trial with both master and slave modes included, and afterward a one-time $99 license instead of Modbus Poll's $258 combined master+slave cost.
Can I use Modbus Poll's free download for commercial projects?
The free trial is intended for evaluation. For ongoing commercial or production testing work, you need a paid license once the 30-day period ends.
Do I need Modbus Slave too if I download Modbus Poll free?
If your workflow needs a slave device to test against, yes — Modbus Poll only handles the master/polling side, so many engineers pair it with Modbus Slave or switch to a single tool that includes both.