Send Single Command to uArm

How do I send a single gcode command to the uArm from the Arduino IDE Serial Monitor? I have tried various ways with no success.

I have the PC connected via USB to a uArm Controller.

Did you connect both your PC and the uArm to the uArm Controller?

Yes,both are connected.

How do you want to control the uArm? By Arduino IDE on PC or by uArm Controller?

Actually I would like to try both.

Yes, you could try both.

OK, then how do I send a single command? The PC is connected to the controller and the controller is connected to the uArm.

Arduino IDE is open.

If you just want to send a command to uarm through the PC, you can connect uarm to PC through usb, select the corresponding serial port, open the serial port simulator and send the command directly.
If you want to send commands to the uarm through the uarm controller, you need to connect the uarm controller through usb, and connect the uarm controller to uarm through type-c to , and write the corresponding serial port data processing function.