Device for a tachograph for checking the correct working of an instrument connected to the tachograph for displaying the vehicle speed and/or device connected to the tachograph for limiting automatically the vehicle speed

摘要

The tachograph is equipped with a pulse generator which can be activated by at least one control to produce a sequence simulating a road speed signal. This sequence is transmitted over the tachograph output wiring for a check on the speedometer and/or on equipment which imposes an automatic speed limit on the vehicle. A nonvolatile memory in the tachograph registers the date and time of at least the most recent speed signal simulation, and/or counts the number of such simulations performed within a fixed unit of time. The duration of each simulation is measured by a timer.