PC is a Sony VAIO laptop PCG R505B running XP SP2. I want to connect a data logger to COM1, but its program cannot read COM1. It works OK on a desktop. The problem seems to be that the internal modem on COM3 interferes with COM1. I have set up a hardware profile ('No Modem') which disables the modem, and disables the 'Telephony' service. Still no go. I have got it to work by disabling COM1 in the profile, starting the machine, (which then cannot grab COM1). I then enable COM1 and can run the data logger. But how do I find out what is grabbing COM1 so I can disable it to make this procedure more user friendly?
I wondered about using Security event logging, but cannot see how you can set auditing on a com port.