# Reading Mavlink special messages, using pymavlink

**URL:** <https://discuss.bluerobotics.com/t/reading-mavlink-special-messages-using-pymavlink/4965>\
**Category:** Blue Robotics Software\
**Tags:** pymavlink\
**Created:** [April 30, 2019, 12:19am UTC](https://discuss.bluerobotics.com/t/reading-mavlink-special-messages-using-pymavlink/4965 "2019-04-30T00:19:45Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![alexxtasi](https://avatars.discourse-cdn.com/v4/letter/a/f14d63/32.png) [@alexxtasi](https://discuss.bluerobotics.com/u/alexxtasi)\
**Post date:** [May 2, 2019, 12:26am UTC](https://discuss.bluerobotics.com/t/reading-mavlink-special-messages-using-pymavlink/4965/3 "2019-05-02T00:26:23Z")

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Hey @patrickelectric thanks for the answer !!  
you didn’t mention anything about time or pressure, so I suppose I was right on those.  
To sum up … mavlink messages I need are:

- time - SYSTEM\_TIME.time\_unix\_usec
- depth - VFR\_HUD.alt
- pressure - SCALED\_PRESSURE2.press\_diff
- temperature - SCALED\_PRESSURE2.temperature (I use the Bar30 sensor)
- heading - VFR\_HUD.heading

please correct me if anything of the above is wrong.

I also encountered some difference between mavlink time and local time (on the system python is reading the messages) - a very small one, but in a case of video timing might be critical.  
I also saw this mentioned in [Writing telemetry data (specifically, depth) to gopro video? - #5 by mspencer](https://discuss.bluerobotics.com/t/writing-telemetry-data-specifically-depth-to-gopro-video/1833/5)

Is there a workaround on this ??  
and what is the status of [Add option to set system time via GCS](https://github.com/bluerobotics/ardusub/issues/131) ??

many thanks

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