Detecting new COM port created by USB-serial convertor

Hi,

I would like to connect an old Agilent 33120A to my computer using a serial port (i don't have any gpib cable). Since I don't have a serial port on my computer I decided to buy and connect a USB to Serial converter. A new serial COM port is created. I can see it on the Windows hardware window.

However I cannot see it on the Matlab test and measurement tool. It only shows COM3 (specific port I think that I cannot access) but not COM4 which I just created thanks to my USB to serial converter.

What should I do? Did I do anything wrong? I have windows 7 and Matlab 2011b.

Thanks.

Regards

Guillaume

Answer 1

[Kaustubha Govind]

Are you able to use the SERIAL command to open the port?

    s = serial('COM4');
    fopen(s)
    %s.Status should be 'open'
    fclose(s)

The documentation suggests that there might be issues with the driver provided by the vendor of the USB to serial converter if this doesn't work.

Answer 2

[Walter Roberson]

Note that you need to quit and restart MATLAB in order for new USB ports to be recognized. The table of devices is only scanned once, the first time that a serial device is asked about. Enhancement requests have been made to give a way for users to trigger a re-scan.

Answer 3

[Guillaume]

I pressed the "scan for all hardware button" and it works now! I can see the new COM port created by the USB serial convertor! Thanks Guillaume