Definition
Parking Guidance Display (Parking Guidance, Vacancy Guidance Display) is an electronic display screen (LED/LCD) installed at parking lot entrances, intersections, or on each floor's passages. It shows the number of available spaces in each area or floor in real time, guiding drivers to quickly find available parking spots, reducing cruising time within the lot and vehicle emissions, and improving parking efficiency and user experience.
Parking guidance displays work in coordination with parking space detection systems (magnetic sensors, video recognition, ultrasonic sensors), parking guidance systems (parking indicator lights), and reverse parking finding systems to form a complete smart parking solution.
Technical Features
Data for parking guidance displays comes from parking space detection devices such as magnetic sensors, video recognition, and ultrasonic sensors. The data is uploaded to the cloud platform via IoT SIM cards or wired networks, where the number of available spaces in each area is calculated in real time and then sent to the guidance displays. Multi-level guidance is supported (Entrance → Area → Parking Spot), and some systems support spot-level guidance (parking indicator lights).
Use Cases
Parking guidance displays are widely used in large parking lots of malls, hospitals, airports, office buildings, tourist attractions, etc. After data is uploaded to the cloud platform via IoT SIM cards, it is delivered to the guidance displays. SimtoLink provides stable data transmission and a dedicated APN for parking guidance systems, ensuring real-time updates of vacancy information and a smooth user guidance experience.
How a space count travels from the stall to the screen
The number on a parking guidance screen is the remaining spaces for a zone, not the raw pulse from one detector. Magnetic, video, or ultrasonic sensing first decides whether a stall is occupied. The platform sums by zone, then sends the remainder to the entrance screen, the floor screen, or the aisle screen. An IoT SIM may sit on the detector uplink or on the screen downlink. Do not collapse those directions into "the screen is counting cars itself." Each stall needs a stable identity and belongs to exactly one zone. A stall drawn into two zones makes the entrance total larger than the sum of the floors. When a detector goes offline, that stall should leave the countable set for the moment, or be marked unknown. It must not keep the last "free" state.
Multi-level guidance also requires the numbers to be traceable level by level. The entrance shows the whole site, a zone screen shows that zone, and the stall light points at one stall. Cellular fits yards where detectors are scattered and cable tray cannot reach them. If a screen receives its number only over the SIM, a short outage should hold the last frame and show the data time, not freeze on an expired number that still looks fresh. In a mechanical garage, stall state comes from the platform and interlocks. Do not apply the magnetic-sensor logic of a flat stall to a lift-and-slide deck that is still moving.
Offline detectors still counted as free spaces
A common mistake is that, after a detector drops, the platform freezes the last state as "free." Free spaces on the screen keep accumulating, and drivers enter to find nothing. Past an agreed offline time, count the stall as unavailable or unknown, and distinguish it on the screen from a real free space. Another mistake is video detection treating a vehicle driving across the stall line as occupancy. The number drops for a moment, then does not recover when the vehicle leaves, and drivers hunt between floors. Occupancy needs a stable interval. The jitter of just entering and just leaving should not each count as a change in spaces left.
Refreshing the screen and reporting detections is not better the faster it goes. Uploading every stall every second over the SIM does not necessarily cut the aggregation delay, and it does raise cost and collisions. Zone totals can be computed on a local gateway, and only the remaining count per zone needs to leave. For acceptance, unplug one zone's detection path. After the agreed time the entrance screen should reduce the countable stalls or mark that zone unknown, not keep showing the free count from before the cable was pulled. When the path returns, the number should follow the current detection. Do not backfill the offline period's historical free count as a track.
An unknown stall must not keep showing as free
After one zone's detection path is unplugged, the entrance screen should, within the agreed time, reduce the countable stalls or mark that zone unknown. It must not keep the free count from before the cable was pulled. After recovery the number follows current detection. Do not turn historical free counts from the outage into a track of changes. A vehicle crossing the line while moving should not change the remainder immediately. Add or subtract only after occupancy is stable. If one stall is assigned to two zones, the entrance total exceeds the sum of the floors. Fix the assignment before arguing about refresh rate.
When a screen misses new numbers for a short time, show the data time of the last frame, so drivers do not treat an expired free count as just updated. Where detectors are scattered, sum each zone locally and send those remainders over the SIM. There is no need to upload every stall every second. A free-stall test for a flat space does not apply to a garage whose deck is still moving. After the unplug, line-crossing, and recovery checks, the number on the guidance screen means a place that can be parked in at that moment.