I would like to use 2 telemetry devices on the pixhawk.
One like a short range 433 or 868 mhz radio and one 4G (LTE) like UAV MATRIX.
The reason is that we can use the short range Radio for take off and landing and the LTE for long range monitoring the flight. We cannot use only LTE because the connection is sometimes not reliable when we fly in remote areas.
Both solutions use serial RX/TX, 57600 baud. TX from pixhawk can go to RX on both without a problem, but TX from the units cannot be tight together to RX on the pixhawk.
This way we would have reliable control and Telemetry during take off and landing and can monitor the flight for long range, even when the connection is intermittent. It would also serve as redundancy in case 1 of the units would fail.
Yes, I read that as well. But that will add a companion computer and a lot of complexity. I’m a fan of KIS, keep it simple.
I will give it a try on 2 serial ports and see what happens. Actually, we would only give commands in emergency situations. We’re flying large survey missions and for example we could fly into the rain. We just want to be able to give an RTL command or cut short on the mission by skipping some way points. Worse case scenario will be the command will be received twice.
Most of the time (almost always) we will be definitely out of the range of the short range radio, so the command will only be received by the LTE.
Yes, unbelievable. I did some more experiments today and noticed the pixhawk stops listening to serial 1 as soon as the other serial port is connected. It keeps on sending status messages, but doesn’t respond to any incoming message.
I also tried vice versa. So connect the secondary serial port first and then connect serial 1. Same result. Serial 1 keeps silent.
@Verloop ArduPilot can support several simultaneous mavlink connections for redundant control. I commonly have 2 links on my aircraft, and sometimes have 3.
The key to this is ground station support for multiple links. MissionPlanner is a bit limited for that, I use mavproxy for multi-link
I think MissionPlanner can do it though and what we need is a wiki update to show how.