# Find QCM

Once you have set connected your PC to the QCM200 with the supplied RS232 cable, the software can automatically "find" which port the QCM200 is on. If you have changed the baud rate from the default value of 9600 bps, change it back to 9600 bps from the front panel of the QCM200. When you select "Find QCM" from the software menu, the PC will try to establish RS232 communications with the QCM. You don't need to tell the software which COM port the QCM200 is connected to; the software will poll all available COM ports, looking for an appropriate reply to the "I" (Identification) query.
If the software does not find the QCM200, the first things to check are the baud rate and the cable. Make sure that the cable is plugged in both to the QCM200 and the PC. Make sure you are using a standard RS232 cable, not a "null modem" cable. Verify that the QCM200 is set to 9600 baud.
If you've made sure that the baud rate and cable are correct, make sure that no other software application has allocated the COM port that the PC will use to communicate with the QCM200. Even if an application is not currently using a COM port, it may have allocated that port and will not allow it to be used until the application closes. The best way to make sure that no other application is using the COM port you need is to close all applications other than the QCM200 software.