# Mav\_0\_config not seen **URL:** \ **Category:** MAVLink\ **Created:** [March 9, 2019, 2:23am UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926 "2019-03-09T02:23:09Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![team18049](https://discuss.px4.io/letter_avatar_proxy/v4/letter/t/b3f665/32.png) [@team18049](https://discuss.px4.io/u/team18049)\ **Post date:** [March 9, 2019, 2:23am UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/1 "2019-03-09T02:23:09Z")
I am trying to set up a unique mavlink configuration for my drone using the px4 but we are running into issues. The setup we need to use is a baud rate of 115200 on telem2. When looking over the documentation for the px4 it mentions that we should be using mav\_0\_config setting and a few of the other mav\_0\_\* settings so that we can set the mavlink setting. When we look for this parameter on QGroundControl we can not find any of these parameters. Is this something that is a hidden parameter? Are we able to see these at all or how are we able to change these parameters? We have updated our px4 to the latest firmware and are still running into the same issue. Any help would be much appreciated. ---
**Author:** ![LorenzMeier](https://discuss.px4.io/user_avatar/discuss.px4.io/lorenzmeier/32/17_2.png) [@LorenzMeier](https://discuss.px4.io/u/LorenzMeier)\ **Post date:** [March 9, 2019, 9:55am UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/2 "2019-03-09T09:55:04Z")
Have you followed all these steps? [https://docs.px4.io/en/peripherals/serial\_configuration.html](https://docs.px4.io/en/peripherals/serial_configuration.html) - at which point does it fail? ---
**Author:** ![team18049](https://discuss.px4.io/letter_avatar_proxy/v4/letter/t/b3f665/32.png) [@team18049](https://discuss.px4.io/u/team18049)\ **Post date:** [March 10, 2019, 6:07pm UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/3 "2019-03-10T18:07:02Z")
We are looking at the trouble shooting section of that link. The failing part is that our parameters do not show up and we do not know how to actually change the firmware so that we are able to see the mavlink commands that are found here [https://docs.px4.io/en/advanced\_config/parameter\_reference.html#mavlink](https://docs.px4.io/en/advanced_config/parameter_reference.html#mavlink) ---
**Author:** ![asheshad](https://discuss.px4.io/letter_avatar_proxy/v4/letter/a/87869e/32.png) [@asheshad](https://discuss.px4.io/u/asheshad)\ **Post date:** [March 11, 2019, 3:11am UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/4 "2019-03-11T03:11:33Z")
I am facing similar issues too. Unable to find some parameters from QGC. However, this is not consistent across all Pixhawk boards. I am interested in understanding how some parameters appear and some do not. Is this PX4 Firmware issue or board issue? Any help here is very much appreciated. ---
**Author:** ![hamishwillee](https://discuss.px4.io/user_avatar/discuss.px4.io/hamishwillee/32/3469_2.png) [@hamishwillee](https://discuss.px4.io/u/hamishwillee)\ **Post date:** [March 12, 2019, 5:00am UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/5 "2019-03-12T05:00:03Z")
> [@team18049](#): > > the mavlink setting. When we look for this parameter on QGroundControl we can not find any of these parameters. @team18049 You should not have to do anything special for these to show up. I just tested this with daily build, QGC 3.5 and Pixhawk 4 Mini. The parameters do show up in QGC in the settings when I look for them: [Redirecting to latest version of document (master)](https://docs.px4.io/en/advanced_config/parameters.html#finding-a-parameter) What hardware are you using? ---
**Author:** ![hamishwillee](https://discuss.px4.io/user_avatar/discuss.px4.io/hamishwillee/32/3469_2.png) [@hamishwillee](https://discuss.px4.io/u/hamishwillee)\ **Post date:** [March 12, 2019, 5:02am UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/6 "2019-03-12T05:02:07Z")
Parameters show up when the module that uses them is included in the build. That is why on FMUv2 boards you’ll sometimes see missing parameters - because a lot has had to be disabled to allow the firmware to fit into the 1Mb limit on those boards. ---
**Author:** ![asheshad](https://discuss.px4.io/letter_avatar_proxy/v4/letter/a/87869e/32.png) [@asheshad](https://discuss.px4.io/u/asheshad)\ **Post date:** [March 12, 2019, 10:01am UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/7 "2019-03-12T10:01:09Z")
@hamishwillee, Thanks for the reply. This makes sense. I am also customizing the complete boot up sequence using a rc.txt (as mentioned here: [https://dev.px4.io/en/concept/system\_startup.html#replacing-the-system-startup](https://dev.px4.io/en/concept/system_startup.html#replacing-the-system-startup) ) in which I start only the modules that I want. So my question is: 1. Does the parameters depend on the modules being built as mentioned in CMAKE, or the modules being started as mentioned in rc.txt ? 2. How do I find the mapping between the parameters and the modules? Thanks in advance ---
**Author:** ![team18049](https://discuss.px4.io/letter_avatar_proxy/v4/letter/t/b3f665/32.png) [@team18049](https://discuss.px4.io/u/team18049)\ **Post date:** [March 12, 2019, 4:12pm UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/8 "2019-03-12T16:12:45Z")
@hamishwillee We are using the pixhawk 1 px4. It is the FMUv2 board which is why are not seeing the parameters. I thought I remember reading that it was possible to show these disabled parameters by adding/removing a few things from the firmware ([https://docs.px4.io/en/peripherals/serial\_configuration.html#parameter\_not\_in\_firmware](https://docs.px4.io/en/peripherals/serial_configuration.html#parameter_not_in_firmware)), I just don’t know how to do this. ---
**Author:** ![hamishwillee](https://discuss.px4.io/user_avatar/discuss.px4.io/hamishwillee/32/3469_2.png) [@hamishwillee](https://discuss.px4.io/u/hamishwillee)\ **Post date:** [March 12, 2019, 9:36pm UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/9 "2019-03-12T21:36:46Z")
> [@asheshad](#): > > 1. Does the parameters depend on the modules being built as mentioned in CMAKE, or the modules being started as mentioned in rc.txt ? It is in the cmake configuration. So for FMUv2 you can see a bunch being disabled here: [https://github.com/PX4/Firmware/blob/master/boards/px4/fmu-v2/default.cmake](https://github.com/PX4/Firmware/blob/master/boards/px4/fmu-v2/default.cmake) A bit of docs on this here: [Writing your First Application · PX4 Developer Guide](https://dev.px4.io/en/apps/hello_sky.html#build-the-applicationfirmware) > [@asheshad](#): > > 1. How do I find the mapping between the parameters and the modules? There is no documentation of the mapping, but often you can guess from the name or purpose. The easiest way though is to just do a search on PX4/Firmware repo for the parameter name. The module name is then obvious from the file path of the definition. ---
**Author:** ![hamishwillee](https://discuss.px4.io/user_avatar/discuss.px4.io/hamishwillee/32/3469_2.png) [@hamishwillee](https://discuss.px4.io/u/hamishwillee)\ **Post date:** [March 12, 2019, 9:41pm UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/10 "2019-03-12T21:41:18Z")
> [@team18049](#): > > @hamishwillee We are using the pixhawk 1 px4. It is the FMUv2 board which is why are not seeing the parameters. I thought I remember reading that it was possible to show these disabled parameters by adding/removing a few things from the firmware ([Redirecting to latest version of document (master)](https://docs.px4.io/en/peripherals/serial_configuration.html#parameter_not_in_firmware)), I just don’t know how to do this. See the comment I made to asheshad. - Docs on this in [Writing your First Application · PX4 Developer Guide](https://dev.px4.io/en/apps/hello_sky.html#build-the-applicationfirmware) - File to modify [https://github.com/PX4/Firmware/blob/master/boards/px4/fmu-v2/default.cmake](https://github.com/PX4/Firmware/blob/master/boards/px4/fmu-v2/default.cmake) NOTE! There is a reason these are disabled. If you are really using Pixhawk 1 board that must have FMUv2 then it only has 1 MB of memory. That is not a lot. If you enable a module to add whatever functionality you need, you may have to disable another module. I can’t offer much advice on that. If your hardware is relatively new, it may not actually require FMUv2 - you may be able to install FMUv3. But to do this you might need to do a bootloader update [Redirecting to latest version of document (master)](https://docs.px4.io/en/config/firmware.html#bootloader) ---
**Author:** ![yura](https://discuss.px4.io/letter_avatar_proxy/v4/letter/y/e0b2c6/32.png) [@yura](https://discuss.px4.io/u/yura)\ **Post date:** [March 16, 2019, 8:08am UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/11 "2019-03-16T08:08:32Z")
Hi @asheshad & @team18049, I had the same issue with firmware v1.8.2, have to compile v1.9.0 (from master) and now I can see MAV\_\* parameters as expected. Note that I’m using Pixhawk 1 (HW 2.4.8), so my chipset STM32F427 is Rev3, and I built and flashed px4fmu-v3\_default firmware see my post: > [@\[Resolved\] PX4 & Companion on latest Firmware](http://discuss.px4.io/t/resolved-px4-companion-on-latest-firmware/10006): > > Hi, My current setup: HW: PX4FMU 2.4.8 with STM32F427 Rev3 SW: PX4 Firmware v1.8.2 I’m trying to build [GitHub - NVIDIA-AI-IOT/redtail: Perception and AI components for autonomous mobile robotics.](https://github.com/NVIDIA-AI-IOT/redtail) project, and currently I stack on configuring Companion mode based on this howto: [PX4-Devguide/pixhawk\_companion.md at master · PX4/PX4-Devguide · GitHub](https://github.com/PX4/Devguide/blob/master/en/companion_computer/pixhawk_companion.md) My problem is following: I cant find MAV\_1\_CONFIG / MAV\_1\_MODE / SER\_TEL2\_BAUD parameters in the QGC I can only see the following MAV\_\* paramet… ---
**Author:** ![yura](https://discuss.px4.io/letter_avatar_proxy/v4/letter/y/e0b2c6/32.png) [@yura](https://discuss.px4.io/u/yura)\ **Post date:** [March 16, 2019, 8:53am UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/12 "2019-03-16T08:53:38Z")
BTW, vs changing MAV\_\* parameters directly, I would recommend to use the following approach, so if any issues, you can remove the SD card and connect pixhawk to QGC via usb: 1. create following path & file in your SD card: `/etc/extras.txt` 2. add the following content: `mavlink stop-all` `mavlink start -d /dev/ttyS2 -b 921600 -r 20000 -m onboard` 3. powercycle pihawk with SD card note the following mapping for Pixhawk 1: `Micro-USB -> /dev/ttyACM0 (Console)` `TELEM1 -> /dev/ttyS1 (MAVLink)` `TELEM2 -> /dev/ttyS2 (MAVLink)` `GPS -> /dev/ttyS3 (GPS1)` `SERIAL5 -> /dev/ttyS5 (NSH Console)` `SERIAL4 -> /dev/ttyS6 (GPS2)` for more info, see the following links: [https://dev.px4.io/en/concept/system\_startup.html#starting-additional-applications](https://dev.px4.io/en/concept/system_startup.html#starting-additional-applications) [https://dev.px4.io/en/middleware/modules\_communication.html#mavlink](https://dev.px4.io/en/middleware/modules_communication.html#mavlink) ---
**Author:** ![Murray\_Louw](https://discuss.px4.io/user_avatar/discuss.px4.io/murray_louw/32/7850_2.png) [@Murray\_Louw](https://discuss.px4.io/u/Murray_Louw)\ **Post date:** [September 24, 2021, 3:38pm UTC](https://discuss.px4.io/t/mav-0-config-not-seen/9926/13 "2021-09-24T15:38:43Z")
Another reason why parameters may not be showing is because of port conflicts. I was trying to set up a companion computer on a Pixhawk 4 mini. It only has one telemetry port, so I tried to change MAV\_1\_CONFIG from Disabled to TELEM1, then reboot. But other MAV\_1\_\* params would still not show, because MAV\_0\_CONFIG was pointing to TELEM1. After setting MAV\_0\_CONFIG to a random port, and TELEM1 was only set at MAV\_1\_CONFIG, then the other params showed again. However, I will use MAV\_0 for the comapanion computer. [https://docs.px4.io/master/en/advanced\_config/parameters.html](https://docs.px4.io/master/en/advanced_config/parameters.html) [https://docs.px4.io/master/en/peripherals/serial\_configuration.html](https://docs.px4.io/master/en/peripherals/serial_configuration.html)