Is there any way for an arduino using COM3 check the status of the other com ports of the system it is plugged into? I woul dlike to have my arduino connected via USB to a laptop(using com3). I will have some other program running that may be using COM1. I would like to have the arduino check com1 to see if it is currently in use. Any way to do this with code only running on the arduino? Thanks
Any way to do this with code only running on the arduino?
No. The only way for the Arduino to communicate with the PC, to find out what is happening on the PC is to send it serial data, and hope that there is some application running on the PC that can reply to it.
If you're not willing, or able, to have an application running on the PC that the Arduino can talk to, you can't get the information that you want.
What would you do with that information, if you could get it? You would not be able to communicate with the hardware on the other end of the other serial port, except through an application on the PC that acted as a go-between.