PL2303 Success story

Thanks in part to reading Lampros’ help to other PL2303 users, I got an RS232 serial fax modem working on my Macbook Pro. Here is a complete step-by-step which hopefully will help others using the Pluggable device.
A few times each year I need to send a fax. I don’t have a fax machine.
My Macbook Pro does not have a phone input or built in modem but I have an old RS232 serial fax modem in perfect working order.
I purchased a Pluggable PL2303 USB to RS232 adapter.
Here is how to install a serial fax modem on a Mac running Snow Leopard using this adapter.

  1. With the adapter disconnected, Install the Prolific driver for Snow Leopard found at
  2. Plug the adapter into a USB port. You should get a window recognizing it and asking to set it up.
  3. If you’re not there, go to System Preferences and click on Network. In Network, click on “USB Serial Controller D”. You will get a configuration section.
  4. In the drop-down under configuration, click on “Add configuration”. Name this configuration what you like. I named mine “fax modem”.
  5. Click on the “Advanced” button near the bottom of the configuration section. You will get a window with 5 tabs, labeled “Modem”, “DNS”, “WINS”, “Proxies”, and “PPP”. Click on “Modem”.
  6. Fill in the modem fields “Vendor”, “Model” and “Dial Mode” using the field drop downs. I found my Vendor, Zoom, in the drop down list but my model (56K faxmodem) was not in the Model drop down so I guessed and picked “Universal 115K”.
    I left the defaults - Dial Mode to “Wait for dial tone before dialing”, Dialing to Tone and Sound to On, and “Enable error correction and compression in modem” checked.
    Click OK. Click Apply. Close System Preferences.
  7. Adding the fax to Printers and Faxes in System Preferences cannot be done the usual way, by clicking the + sign. Instead, the fax printer will be installed using the CUPS administrative tools as follows:
    Open a browser and type “http://localhost:631/” (without the quotes) into the browser’s address field.
    This should bring up the CUPS (Common Unix Printing System) page.
  8. Click on the “Administration” tab. Under “Printers”, click on “Add Printer” and log in to CUPS as your system administrator.
    You will get the “Add Printer” screen.
  9. Under “Local Printers” select “Fax”. Then click “Continue”. You will get the URI screen with the word “fax” in the “Connection” field. Fill in the field so it looks like this:
    Then click “Continue”. You will get the name, description and location screen.
  10. Fill in the fields as indicated. For name, I used “faxprinter”. For Description, I entered “fax modem”. For Location I entered “Serial Port”. I left “Share this Printer” unchecked. When done, Click Continue. You will get the PPD screen.
  11. Ignore the “Make” field. Next to “Or Provide a PPD File”, click on “Choose File”.
    Navigate to boot disk (usually Macintosh HD)/ System / Library / Frameworks / ApplicationServices.framework / Versions / A / Frameworks / PrintCore.framework / Versions / A / Resources / and choose the file “Fax.ppd”.
  12. Click “Add Printer” and you are done.

Thanks, Lampros and Plugable!
Vic Pierce

Thanks so much for your kind words Victor! And thanks for the step-by-step for your case – others doing similar things will find your steps useful!

(We are also grateful to have Lampros on our staff - he handles many of our most involved cases!)

Hi Victor!

Many thanks for your kind words and for your excellent step-by-step!

Please let us know if you ever need any help with any of our products on the Mac!
We do our best to put up guides to make life easier for our customers and any feedback or suggestions means a lot to us!

We’re here to help!
Have a great week!