Hi Bo,

Does the depth actually update in QGroundControl?

If the depth is correctly updated in QGC I suggest you try to connect to the script on the companion computer by running screen -r wldriver. This script should print out what it is sending, so you should be able to see if it receives the data correctly and if sending works without error messages.
(ref https://github.com/bluerobotics/companion/blob/master/.companion.rc#L25 )