Wrong CTUN.SAlt sonar values read by APM Planner from log


It seems that some CTUN.SAlt values are not read correctly by APM Planner from the log files.
SAlt values never exceed 0.02, this can be seen on the graph and on the grid views although
Mission Planner read the correct values from the same log files.

I have attached screenshots for comparison.

Does somebody has a workout for this or is it a bug which hopefully will be fixed soon ?

Thank you.


I can take a look, if you can post a log it helps speed up the process. Thx :slight_smile:

Hello Bill,

Thank you for taking time to have a look about this, you’ll find the log file #126 used for these
screenshots here:

Please note that the SAlt values are coming from another sensor connected to Pixhawk ADC6.6V input
therefore they do not match the other real altitude values but it does not change the problem.


I just plotted with latest master and it seems correct to me. What version of AP2 are you using?


PS: you can download the latest build to test (of master branch) here firmware.diydrones.com/Tools/APM … 015-09-16/

Hi Bill,

I was using latest V2.0.18 downloaded from ardupilot.com/downloads, I have upgraded
with your link pointing to V2.0.19-rc1 and now it shows the correct values and plot !

I didn’t think to try a release candidate for fixing this problem and I didn’t find a version/release history.

Thank you for having spent some time on my issue, problem fixed.