A checkpoint works as a chain: the camera gives a frame, the server finds the number plate in it and reads it, the checkpoint compares the plate with its lists and, depending on the decision, clicks the relay. Below, the causes are sorted by symptom: no passage in the log at all, a passage in the log but the barrier stays down, or plates read with mistakes.
No passage in the log
A vehicle has driven through, but the checkpoint’s log has no row for it. Check in order:
- The checkpoint’s mode. In the “Off” mode the checkpoint recognises nothing and keeps no log. The mode is on the “Settings” tab of the checkpoint card.
- The checkpoint camera. On the “Cameras” tab, a camera with the right direction is linked to the checkpoint. The same tab has the “Frames in 24 h” line: how many frames were requested and how many arrived. Delivery below 90% is highlighted in red: the camera answers intermittently, or the site’s connection is narrow.
- The plate looks Russian. Our recognition writes to the log only plates that fit the Russian GOST formats: cars and lorries, taxis and buses, trailers, motorcycles and tractors, transit plates. It skips foreign plates and non-standard signs silently; how many such readings were filtered out is shown on the “Cameras” tab in the “Filtered out” line. Plates from your own ANPR camera are recorded as they arrive.
- The plate is visible in the frame. A plate narrower than 60 pixels cannot be read at all; a plate is read reliably from 120 pixels. If the plates in the frame are smaller, the “Cameras” tab shows the “Number plate too small in the frame” line with their average width, and the log is empty although vehicles drive past: such a camera films the whole street. Zoom it in on the spot where vehicles pass closest, or move it closer to the lane. Dirt, snow, headlight glare and a plate at an angle also stop the plate from being found.
- A repeat. The same plate in the same direction is not processed again until the debounce time from the checkpoint settings has passed. And a vehicle that simply stands in the frame gets into the log no more than once every ten minutes.
If plates come to the checkpoint from your own ANPR camera, check its sending address: after “Change secret” is pressed in the checkpoint settings, the old address is no longer accepted, and the new one has to be entered in the camera.
The passage is in the log, but the barrier did not open
A log row has a decision and a reason. The reason tells you what to do.
| Reason in the log | What to do |
|---|---|
| “Observe: would open” | The checkpoint is in the observation mode and does not touch the barrier. When the trial is over, switch the mode to “Auto”. If the checkpoint has a schedule, outside its window the automatic mode also behaves as observation |
| “Plate read unreliably” with a percentage | The plate was read below the checkpoint’s confidence threshold. Improve the frame (see below). The threshold can be lowered in the settings, but a threshold that is too low also opens on misreadings |
| “Plate is not on the list” | The plate is not on this checkpoint’s allow list, or the pass is not valid right now: it has expired or not started yet, today is the wrong day of the week, it is the wrong time of day, the pass is for the other direction, the limit of passages is used up, or the pass is turned off. Each checkpoint has its own list: a pass added at the neighbouring checkpoint does not work here. Check the plate itself too: the cut-out in the log shows what the camera read |
| “Plate is on the block list” | The block list beats the allow list: remove the plate from the block list if it is there by mistake |
| “Relay error” | The checkpoint decided to open, but the relay did not answer. The last error is shown on the “Relays” tab: the address, the port, whether the relay can be reached from the internet |
- Search by number plate
- Filter by decision
- Passage: frame, plate, decision, time
- Export the log to CSV
Plates are read with mistakes
- Size. A plate in the frame must be at least 120 pixels wide. Below that, the three-digit region code is the first to go: ‘190’ is read as ‘19’. Zoom the camera in or fit a longer lens.
- Angle and light. The camera should look at the plate as straight as possible; at night the plate needs lighting; the sun and headlights must not shine into the lens.
- The key frame. In the camera’s settings, set the key frame interval to 1 or 2 seconds: recognition takes a fresh frame, and with rare key frames the vehicle has time to drive through.
- One error. The “Allow one recognition error” tick box in the checkpoint settings lets in a plate from the allow list where a similar character is confused (0 and O, 8 and B) or one character is extra or missing. It never applies to the block list.
The server corrects obvious mix-ups of digits and letters on their own: the position in the GOST format tells where a letter must stand and where a digit. What exactly was read is shown by the plate cut-out in the log.
It opened for the wrong vehicle
- The log row has the reason “Pass” marked match with one error: the plate is similar to a plate on the allow list. If this is not acceptable, clear the “Allow one recognition error” tick box.
- The reason “Free exit”: the checkpoint opens for any vehicle that is leaving. It is turned off in the checkpoint settings.
- The decision “Opened manually”: the row has the name of the employee who pressed “Open”.
If this did not help
Write to us via the Contacts page or on Telegram: the name of the checkpoint, the time of the passage and the vehicle’s plate. The frame and the plate cut-out in the log usually show at once what the matter is.
See also
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