Product features:

When trailers are shunted around in distribution yards or docks a “Tug or Dock Spotter” moves the trailer with only the Red emergency air line connected and no electrics.
So automatic systems for height, GPS, fault diagnostic & telemetry transmitters don’t work.

The DAB Ancillary controller will power all of these and it knows which direction and what speed the trailer is doing, so it can sound alarms or transmit data as to time, speed, distance etc. When the trailer is then powered electrically from a tractor unit, it recognizes this and switches power to recharge the internal batteries ready for the next time.