How do I get around the Modbus Poll 10-minute trial limit?
Updated 18 September 2026
Modbus Poll's free download is a trial: it stops communicating after about ten minutes per session until you buy a licence. There is no trick to remove that — it is how the trial is meant to work, and buying the licence is the right thing to do if you rely on Modbus Poll's desktop features. But if you just need to read or write a few registers without a countdown, Easy Modbus is genuinely free with no time limit, and it runs on the phone already in your pocket.
What the limit actually is
Modbus Poll by Witte Software is commercial software with a free evaluation. The evaluation is fully featured but disconnects after roughly ten minutes, so you reconnect to keep going. It is a fair trial design, not a bug — the intent is that people who use it for real buy a licence (around US$129, with the matching Modbus Slave sold separately). If Modbus Poll is your daily desk tool, that licence is worth it.
When you don't need to buy anything
Plenty of Modbus jobs are not “sit at a Windows desk for an hour” jobs. They are “walk up to a meter, read six registers, maybe change a setpoint, leave.” For those, a free tool with no timer is simply less friction — and a phone beats finding a laptop and a network port in a plant room.
| Modbus Poll (trial) | Easy Modbus | |
|---|---|---|
| Time limit | ~10 minutes per session until licensed | None — free, no timer |
| Cost to use fully | Paid licence (Slave sold separately) | Free; optional one-time purchase only for unlimited saved control panels |
| Platform | Windows desktop | Android phone/tablet, plus a Windows version |
| Reads & writes registers | Yes | Yes, with guard rails and a one-tap Put it back |
| Works out data type for you | You set it | Yes — ranks the plausible readings |
| Direct USB–RS485 serial | Yes | No — reaches serial through a gateway |
Being fair about it
This is not a knock on Modbus Poll. It is mature, fast, scriptable from Excel, and excellent for bench and development work, and if that is your world the licence pays for itself. The point is narrower: if the ten-minute limit is the only thing in your way and you just need to read or write a register in the field, you do not have to buy anything — there is a free tool that does that part. For the fuller comparison see Modbus Poll vs Easy Modbus and free Modbus Poll alternatives.