I've had an EFIS-D10A and an EMS-D10 on the bench for a while, and just got around to installing them. When I bench tested them with v5.1 firmware and test connectors the DSAB connection worked and the EFIS was able to find the EMS and configure the network with 2 devices. Cut to a couple of months later. Both units have been installed and wired. The EFIS didn't recognize that the EMS was on the bus, so I tied to reconfigure the network, and the EFIS only found 1 device (itself). Lots of wire chasing, etc, nothing helped, so I updated to v5.4 firmware with no change. I've checked out the wiring pretty well, even tried a different harness with nothing but the DSAB lines and power to each unit with no joy. Anyone got any suggestions on what to try next? Yes, it's wired A-A and B-B. 
All other sensors, etc, seem to work just fine.
Nauga
2004 RV-4
All other sensors, etc, seem to work just fine.Nauga
2004 RV-4