If you have a CAN-USB adapter (PEAK + PCAN-View or similar), connect it to the CAN bus and check if there are any messages visible. If there are no messages, the bus likely has physical problems. Check all connections, terminations and that CAN H and CAN L are not the wrong way around.
The proper construction of the CAN bus is essential in the high EMI noise environment caused by the power electronics. If you encounter CAN timeouts or other intermittent problems, especially when the inverters are running, check the CAN bus and improve the EMI protection as much as possible.
- The CAN bus must be a single bus (NOT star or ring) with short stubs. Recommended maximum stub length is 50 cm for baud rates below 1 Mbps, and 30 cm for 1 Mbps baud rate.
- The CAN cable must be well shielded. The shield must be connected to the ground from both ends and all stubs (multipoint grounding). Connect the shield to the inverter pin 35 ENC_GND or directly to the enclosure
- CAN H and CAN L must be twisted, at least 40 turns per meter
- CAN GND must be connected between the devices, the wire must go with the CAN H and CAN L wires inside the same shield. If some device or controller doesn’t have a specific CAN GND, connect the CAN GND wire to the common ground right at the device or controller.
- The CAN bus must be terminated with a 120 Ohm resistor at both ends
- The CAN bus must be kept as far away as possible from any high voltage cables, minimum 30 cm
- All high voltage cables must be well shielded
Can wiring principle for single twisted pair cable and separate CAN ground wire
Can wiring example for 2x2 twisted pair cable, using the other pair as a CAN ground conductor. Termination resistors are not shown in picture.