NRA 15 with cube orange as terrain following radar

We are using NRA 15 altimeter for terrain following configurations:

  1. Autopilot is cube orange

  2. Connected at Telem 2 (Serial 2) with 12 volt dc from separate power source

  3. Serial 2 parameter 9,

  4. rngfnd1_type =11

  5. rngfnd1_min = 10 cm

6.rngfnd1_max=2500 cm

7.rngfnd1_orient = 25

Issue being faced : We are getting the altitude on our GCS but not able to arm as the error message "Rangefinder 1 NO DATA " is coming but if we lift drone at some height then we are able arm it.

In this regard we seek your assistance and guidance.

I have never used the NRA15 (or even heard of it), but I wrote the driver for NRA24 which just got merged to master. One of the key problems with the sensor is that it doesn’t send distances unless the sensor sees some relative movement. This would cause a pre-arm error because ArduPilot thinks the rangefinder is “unhealthy”. The work around I impleted was that in the latest code (not yet in stable release), we pass the rangefinder pre arm checks if we receive “heartbeat” from the sensor, even if we don’t receive distances. Note: this is for the CAN based NRA24 only.
We don’t directly support any other NRA sensor so far, so you will need to seek assistance from nano radar for this issue. I recall someone telling me that Nano radar has a special firmware for their Radars to not have this problem. Best check with them