Where to find custom mode list for MAV_CMD_DO_SET_MODE

[nikhilsnayak3473]

I am trying to understand the offboard control example using ROS2 provided in the official docs and I came across a line of code that I couldn’t understand. The line of code is as follows:

this->publish_vehicle_command(VehicleCommand::VEHICLE_CMD_DO_SET_MODE, 1, 6);

After delving deeper into this line, I landed on this page: Messages (common) · MAVLink Developer Guide

Now my question is, where can I find the list of custom modes for param2 of the MAV_CMD_DO_SET_MODE Mavlink message?

I apologize if my question is not clearly understandable as I am a beginner in PX4 with ROS2. Thank you for your support.

[vurdlok]

Hello, custom mode is the mod you can create.
Here is the example and also ENUM’s for other modes.
Adding a New Flight Mode to Copter — Dev documentation (for ardupilot)
Flight Modes | PX4 User Guide (px4)

[nikhilsnayak3473]

Can I get more details on. 1 and 6 in that line of code

[vurdlok]

Could you please send a file that you are referring to?

[nikhilsnayak3473]

In this particular line
param1 is set 1 and param2 is set to 6
this->publish_vehicle_command(VehicleCommand::VEHICLE_CMD_DO_SET_MODE, 1, 6);

What does 1 and 6 indicate

[vurdlok]

@nikhilsnayak3473

VEHICLE_CMD_DO_SET_MODE

Ok, so as you can see here:

void OffboardControl::publish_vehicle_command(uint16_t command, float param1, float param2)

we use command: MAV_CMD_DO_SET_MODE

in the structure of THIS exact command we have 3 params:

In line: this->publish_vehicle_command(VehicleCommand::VEHICLE_CMD_DO_SET_MODE, 1, 6);

We just use ENUM for VEHICLE_CMD_DO_SET_MODE (ENUM is just the variable that can be shown with name and not with nimbers just for easy use)
Next we have param 1: Mode
Mode is the vehicle mode we want, we can see here what modes we have Messages (common) · MAVLink Developer Guide
Note, that because they are combined, we cant be 100% sure what exactly does 1 mean (need to check flags).
Then we have param 2: it’s the line for the custom mode, we don’t know exactly again, so need to refer in ardupilot or PX4 specification.
And then we have param 3: it’s the submode, in this case we don’t use this, but it could help you when you create your own mode.

In another example I will send this command as:

this->publish_vehicle_command(VehicleCommand::VEHICLE_CMD_DO_SET_MODE, MAV_MODE_STABILIZE_DISARMED, 0, 0);
In this case I will just send a request for stabilized armed mode.

[nikhilsnayak3473]

@vurdlok

Note, that because they are combined, we cant be 100% sure what exactly does 1 mean (need to check flags).
Then we have param 2: it’s the line for the custom mode, we don’t know exactly again, so need to refer in ardupilot or PX4 specification.

Where can I find these specifications?

[vurdlok]

You can read this topic:

Ids of pixhawk's modes

Hello. I have problem with recognizing ids of base_mode and custom_mode in heartbeat messages. Could someone explain me how it is calculated? I was thinking that it simply references to enum values like MAV_MODE_FLAG or something like that but there doesn’t exist values with these ids. For example base mode equals to 81 exists when pixhawk is only plugged in. And base mode equals to 209 exists when pixhawk is armed. These values are close to this (increment +1), so my conclude is that modes a…

[nikhilsnayak3473]

Thank you so much. From this thread i got a clear understanding of param2.
But I didn’t get any clarity regarding why param1 = 1
If you could give some more information in this regard it would be more helpful

[vurdlok]

Actually in this case I just need to read some code, that ROS provided, because it seems that they use some custom mode, where 1 is CUSTOM_MODE: 1, and 6 is CUSTOM_SUBMODE: 6. Something like that. Glad I could help

[nikhilsnayak3473]

After conducting some research and exploring the MAVLink messages documentation, I discovered that setting param1 to 1 enables the custom mode, as indicated in the documentation found here: MAV_MODE_FLAG.

Based on the assistance provided by @vurdlok, here is a brief summary of the solution for this issue:

• param1 is set to 1 to enable the custom mode.
• param2 is set to 6 to indicate the offboard mode.
  • Other options for param2 include:
    • param2 = 1 (MANUAL)
    • param2 = 2 (ALTCTL)
    • param2 = 3 (POSCTL)
    • param2 = 4 (AUTO)
    • param2 = 5 (ACRO)
    • param2 = 6 (OFFBOARD)
    • param2 = 7 (STABILIZED)
    • param2 = 8 (RATTITUDE)

For more information, you can refer to the PX4 Custom Mode file.