The digital tachograph has 4 connectors on its back, labeled A, B, C and D.

The connectors

• Connector A (Port A) powers the tachograph and connects it to the other computers of the vehicle.
• Connector B (Port B) connects the motion sensor of the vehicle.
• Connector C (Port C) is for CAN connections of other devices, such as fleet management and remote download units. Connect the RDU here: it talks to the tachograph on the CAN line of connector C (pins C5 and C7). The tachograph may need remote download switched on for this, see Remote download not enabled.
• Connector D (Port D) has a few outputs and inputs of the tachograph, for example the status line on pin 8, hence the name D8.

Connect pin D8 if you want real time status readings on the web site, such as card insertion, card removal and working status changes. The download itself does not need D8, see D8 Setting.

Installation basics

• Only trained personnel should install RDU units, to avoid warranty problems with the vehicle and with the RDU.
• The installer must be able to use a multimeter and know basic electronics, for example to find fleet management devices that are already in the vehicle.
• The CAN line must have the right resistance: with the RDU connected, about 60 ohm between C5 and C7.
• On Stoneridge tachographs the CAN of connector C (pins C5 and C7) is called CAN2. A DSRC module belongs on the C2-CAN of connector C (pins C1 and C4), not on the CAN of the RDU.
• The connection scenarios help to install the unit and avoid problems later: connection scenarios of the RDU 4G.