J1939 Troubleshooting_En_V1

Communication issues :

The J1939 protocol operates at 250k bit/s, be careful if you have another protocol that communicates on the bus such as CANOPEN which has different speeds.

Check that your CAN H and CAN L wires are not reversed.

Your two CAN H and CAN L wires must not exceed 250 meters, if there are electromagnetic disturbances consider twisting your wires or using a shielded cable.

There must be a 120 Ohm resistor at both ends of the BUS. There is an internal resistor in the COMPACT, to activate it simply make a bridge between the RES and CAN H terminal on the CAN 2 terminal block of the COMPACT. There may be internal resistance in the ECU, consult the manufacturer's documentation or test with an ohmmeter.

The compact reads engine measurements: If the COMPACT ID is not the one expected by the ECU, then the latter will not take into account the orders transmitted (adjustment of the engine speed, starting of the generating set, etc.).

The COMPACT does not read engine measurements: If the ECU ID is not that of the ECU then the COMPACT will never read the measurements that come from the ECU (engine speed, oil pressure, …)

The automatic detection function makes it possible to detect the ID of the ECU automatically, for this to work the COMPACT and the ECU must be the only two communicating devices on the CAN BUS.

The "stub" cable must not exceed 30 cm.