SYS_USE_IO (PX4 parameter) is not found in ArduCopter parameter list

The instructions from the website says If using a Pixhawk that has ports labeled AUX and MAIN, set SYS_USE_IO=0 and connect your ESCs to the AUX-labeled outputs as though they were labeled MAIN .

There is no parameter called SYS_USE_IO
What do I do now?

That’s not an Ardupilot parameter.
To set up dshot with Ardupilot (which I’m guessing is what you’re trying to do), read

Yes, you have to tell the FC to use the AUX channels for the motors rather than the MAIN channels. SYS_USE_IO sets the aux channels to be used as main.
And I just clicked on that link and it’s telling me to use the SERVO_DSHOT_ESC parameter and that parameter also is completely missing from the parameter list. I have been trying to get this thing flying for 4 months.

Mission planner doesn’t even have the PIxhawk 2.4.8 FC listed so I honestly don’t know if I’m running the correct firmware.

That is because the early Pixhawks are identified by FMU (Fight Management Unit) number. A Pixhawk 2.4.8 is FMUV3.

More than likely your Pixhawk is running the bootloader for an FMUv2.

Your real problem is you are using the documentation for the PX4 Flight Stack firmware, not ArduCopter…

Okay, then where do I go, to find out how to make this thing work? I have DSHOT ESCs with a pixhawk 2.4.8 board and I just want to fly it. How do I do that?

I can’t even get the motors to turn in a motor test

So 2 threads your are posting in for the same issue… Read the Wiki for Arducopter if that’s the firmware you want to use.

You are two clicks away…

Read the docs:

Where in that documentation does it tell me how to make the FC use the AUX channels as MAIN channels?