# px4 disconnected from uart

Source: https://forum.modalai.com/topic/2630/px4-disconnected-from-uart
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2023-09-06 23:06:10 UTC by Syed Omair
Replies: 12 · Views: 2417

## Syed Omair · 2023-09-06 23:06:10 UTC

I have the m500 drone. I get error PX4 DISCONNECTED FROM UART. can someone help ???

## Reply by Syed Omair · 2023-09-06 23:14:54 UTC

@Syed-Omair I tried the voxl-uart-loopback tests and I fail all 4 of them. can someone please help!!!!

![Screenshot 2023-09-06 at 6.14.40 PM.png](https://forum.modalai.com/assets/uploads/files/1694042082881-screenshot-2023-09-06-at-6.14.40-pm.png)

## Reply by tom (ModalAI staff) · 2023-09-06 23:21:41 UTC (in reply to Syed Omair)

@Syed-Omair The uart loopback tests are unrelated to this failure. 

Does your M500 have have the dual board or single board solution?

i.e. voxl1 + flight core or voxl-flight all-in-one board

## Reply by Syed Omair · 2023-09-07 00:20:51 UTC (in reply to tom)

@tom said in [px4 disconnected from uart](/post/12212):
> 
> Reply Quote  0  
> 

I believe its all in one board. i have pictures. 

![drone1.jpeg](https://forum.modalai.com/assets/uploads/files/1694046032486-drone1.jpeg) 
![drone2.jpeg](https://forum.modalai.com/assets/uploads/files/1694046034222-drone2.jpeg) 

and thanks for the quick reply !!!

## Reply by tom (ModalAI staff) · 2023-09-07 16:45:15 UTC (in reply to Syed Omair)

@Syed-Omair It looks like you have a Flight Core v2 + VOXL dual board solution. 

FCv2 connects from this port: https://docs.modalai.com/flight-core-v2-datasheets-connectors/#j1---telem1--uart7--voxl-mavlink-default-port

Can you confirm through QGC that TELEM1 is set up with the proper baudrate (921,600)

Also ensure in `/etc/modalai/voxl-mavlink-server.conf` that `external_fc` is enabled

## Reply by Syed Omair · 2023-09-08 01:34:15 UTC (in reply to tom)

@tom apologies I saw this so late.

I cannot connect to qgroundcontrol since the error started showing. it used to automatically connect but it doesn't anymore. I have the correct ip address and everything. I try to initiate a connection from qgroundcontrol but this is what i get.

![Screenshot 2023-09-07 at 8.32.50 PM.png](https://forum.modalai.com/assets/uploads/files/1694136772415-screenshot-2023-09-07-at-8.32.50-pm.png) 

also external_fc was disabled (false) so i made it true.

## Reply by tom (ModalAI staff) · 2023-09-08 17:03:34 UTC (in reply to Syed Omair)

@Syed-Omair You should also be able to connect to QGC over USB using J3: https://docs.modalai.com/flight-core-v2-datasheets-connectors/#j3---usb-connector

## Reply by Syed Omair · 2023-09-08 21:12:45 UTC (in reply to tom)

@tom I’ll be in touch once I get the cable and test it out

## Reply by Syed Omair · 2023-09-15 03:13:49 UTC (in reply to tom)

@tom hey tom. Thanks it worked. I just had to resrt TELEM1 to default settings through qgroundcontrol and then run voxl-configure-mavlink-server and reset the mavlink server to default settings and after that it connected wirelessly automatically.

But on a side note, can you also help me in pairing a taranis x7 transmitter to the m500 drone. I ordered the drone with the frsky transmitter but is it supposed to be on the drone somewhere or does it come separate like shown in the documentation??

like so https://www.youtube.com/watch?v=1IYg5mQdLVI

I am unable to find it on the drone anywhere. thank you.

## Reply by Adrian Hidalgo (ModalAI staff) · 2023-09-18 15:03:55 UTC (in reply to Syed Omair)

@Syed-Omair the receiver should be on the bottom of the drone and you might have the R-XSR receiver instead of the X8R. It's smaller in profile, should look like something below. Bind button on the right corner next to the connector. Follow same binding procedures as the video. 
![a0b34398-8431-42b9-b234-85f5acf3227e-image.png](https://forum.modalai.com/assets/uploads/files/1695049336382-a0b34398-8431-42b9-b234-85f5acf3227e-image.png)

## Reply by Dobry Kolacz (ModalAI staff) · 2023-09-18 19:05:11 UTC (in reply to Syed Omair)

@Syed-Omair Follow the Red/Black/Yellow cables coming out of the flight core to the receiver

## Reply by Syed Omair · 2023-10-06 15:30:22 UTC (in reply to Adrian Hidalgo)

@Adrian-Hidalgo thank you so much. I am sorry I saw this so late

## Reply by Syed Omair · 2023-10-06 15:46:11 UTC (in reply to Dobry Kolacz)

@Dobry-Kolacz thanksss!!!