NMEA 2000 showing no data — checklist

If your d3kOS dashboard shows dashes or zeros for engine data, work through this checklist before posting for help.

1. Check physical connections. The PiCAN-M HAT connects to the NMEA 2000 backbone via a DeviceNet Micro-C connector. Verify the connector is fully seated and the locking collar is hand-tight. A loose connection is the most common cause of no data.

2. Check NMEA 2000 bus power. The NMEA 2000 network requires 12V DC from a dedicated fuse drop. Use a multimeter on the red and bare wires of any T-connector on the backbone — you should read 11.5 to 12.6V with the engine off.

3. Verify CAN bus termination. An NMEA 2000 network must have exactly two 120-ohm terminating resistors — one at each end of the backbone. If you have zero or more than two terminators, the bus will not operate reliably.

4. Check the can0 interface on the Pi. On the d3kOS SSH console, run ip link show can0. The interface should show as UP. If it shows DOWN or does not exist, the PiCAN-M HAT is not being detected by the kernel.

5. Older analogue gauges. If your boat uses analogue (needle) gauges rather than NMEA 2000 instruments, those sensors are not on the NMEA 2000 bus. You need the Yacht Devices CX5106 analogue-to-NMEA 2000 gateway to bring analogue engine data onto the bus.