COM Port in use by another app??

[themacko]

I've certainly never had this problem before on my Mac. I'm using National Geographic TOPO! software along with a Garmin GPS unit connected via a serial-usb adapter. This setup has always worked fine in the past, but for some reason when I try to sync between GPS unit and computer it gives me the error "COM port is in use by another application"

What exactly are COM ports (communication ports, I'm assuming) and how do I re-assign these or clear them?

 

[lurk]

Only one program can have a port open at once. You need to find the other program and quit it first. You can use lsof in the terminal to track the offending proggie down.

 

[themacko]

I understand that only one app can have a port open at once, but I'm not understanding how to determin which app is using the port. I tried running lsof but I couldn't decypher all the output it gave me.

I should also not that I tried syncing immediate after restarting my Mac, before running any other apps. Are COM ports solely related to hardware use?? In example, could my external harddrive or firewire cd-burners being utilizing a COM port preventing me from using this USB port? That doesn't seem like it would cause an issue but maybe I'm wrong.