Pixhawk 4 Mini Serial Ports

I’m using the Pixhawk 4 Mini in my latest build. It has 3 serial ports on the front. 1 for telemetry and the other ls said to be more for a second GPS, or so the manual says. I’d like to use the TX and RX connections on the second port for Mavlink control. However, I cant seem to get it to connect. Is there a setting in QGC I need to change?

I’m using the Pixhawk 4 Mini in my latest build. It has 3 serial ports on the front. 1 for telemetry and the other ls said to be more for a second GPS, or so the manual says. I’d like to use the TX and RX connections on the second port for Mavlink control. However, I can’t seem to get it to connect. Is there a setting in QGC I need to change?

P.S. Sorry for the misprint. I meant 2 serial ports on the front.

Rick