FAQ
Won't install, won't activate, no image, numbers don't match — work through it in this order.
Install and start-up
The camera view is black
In order:
Devices → Virtual devices— is the camera connected? Hit Reconnect.- Graphics driver too old for DirectX 11. Check with
dxdiag. - Running over RDP: some remote sessions have no hardware acceleration. Start with
--render=software.
"Configuration directory is not writable"
%ProgramData%\PreciSim has no write permission. Run the app once as administrator so it
can create the directory; normal privileges are fine afterwards. Do not move it into a user
profile on a production PC — log in as a different Windows account and the calibrations
disappear.
Activation
"Invalid licence key"
Check for transcription errors first: keys contain no I, L, O or U. What looks
like O is a zero; what looks like l is a one. The app corrects those two automatically
but nothing else.
"All seats in use"
Three machines per key by default. Open your account, find the machine you no longer use and deactivate it — the seat is free immediately.
The machine has no internet
Use offline activation: machine code in, activation code out, no network at any point. Steps in Install and activate.
I never got the purchase email
- Check spam for "PreciSim".
- Claim the order by number — the email you paid with is often not the email you sign in with, and that is by far the most common cause.
- Still nothing: write to us with the order number.
I bought source but got no repository invite
Go to Account → Source access:
- Git account not bound yet → use "Bind with GitHub". Do not type a username; the OAuth route cannot get it wrong.
- Bound but the status says Failed → press "Resend the invite".
- Still failing → send us the error message shown on that page.
Calibration results
I get a different value every run
Expected. The virtual camera has a noise model, like a real one. What matters is whether the deviation is inside tolerance, not whether the number repeats exactly. If the spread is wild (mm/px jumping in the third decimal), check the number of poses — fewer than nine makes the solve unstable.
Verify passes here but the real machine is off
The virtual device can only prove your procedure and maths are right. A real machine also has things the virtual one does not simulate by default:
- manufacturing error in the target itself (nominal 5.000 mm may actually be 4.998 mm);
- thermal drift;
- a camera that is not rigidly mounted, or a lens that is not locked;
- uneven illumination biasing circle-centre extraction.
Switch these on in the error model and your procedure gets validated under conditions much closer to reality.
What order do the calibrations go in?
Intrinsics & distortion → Pixel size → Hand-eye → Stage geometry
↘ Galvo field correction
↘ Z focus (independent, but needs a sharp image)
If an earlier one is wrong, the later one cannot be right — and it will not complain. It will hand you a plausible-looking wrong number.
Integration
Can Python call vmc.dll?
Yes. It exports C-style symbols, so ctypes works directly. See
Python quick start.
Can a PLC drive it?
Yes, over Modbus TCP. Register map in Modbus map. A common use is getting PLC-side logic working against the virtual machine before hardware exists.
Commercial
What does "perpetual updates" actually mean?
You pay once and every future version is yours, with no end date. Even if we later charge for a major upgrade, existing customers keep their update rights. It is written into the source licence.
Can I get an invoice?
Yes. After payment, use Account → Orders → Request an invoice. International orders are invoiced automatically by our Merchant of Record; China-region orders are invoiced by us separately, normally within three business days.