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Resistance verification

 icon2025-10-17

Reading data from the FMS connector
Resistance verification

Based on the experience gained from servicing heavy-duty vehicles using FMS interface connections and the varying approaches to vehicle equipment by different manufacturers, we present the following recommendations: When connecting the orange twisted pair to the FMS, it is essential to check the resistance of the bus each time with the ignition switched off. This is particularly important because, in factory configurations, the FMS interface may be connected to a terminal with a terminating resistor. After disconnecting it and connecting the FMS adapter provided by Albatross (catalog numbers GPR000049 and GPR000050), the bus resistance may change and become incorrect. We have observed such cases, for instance, in MAN heavy-duty vehicles.

When installing a terminal connected to the FMS interface in a vehicle several years old, there is no certainty that modifications to the electrical system have not been made during its use. Therefore, each time Albatross terminals are connected to the FMS interface, it is necessary to verify the resistance of the CAN bus to avoid problems during subsequent operation. The correct value is 60 Ohms.

As of xx-yy-zzzz, FMS Adapters from our range will include an optional 120 Ohm resistor. This resistor should be connected between the orange-brown and orange-green wires if the CAN bus resistance measurement shows 120 Ohms.

 

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