RTSystems usb cables are a branded (i.e., customized) FTDI cable. They simply have different USB Vendor (VID) and Product IDs (PID) from generic FTDI USB adapters.

Apple OSX 10.9.x aka Mavericks now has a built in FTDI Driver, com.apple.driver.AppleUSBFTDI.
However, it does not load by default because it does not recognized the custom VID/PID combos that RTSystems cables use.

Many folks have been simply loading the FTDI OEM driver, com.FTDI.driver.FTDIUSBSerialDriver (2.2.18), and this works, but I have been able to reproduce a nasty hang when uploading from chirp to some Yaesu radios, e.g., VX-6.

The workaround is to disable the OEM driver, and modify and load the Apple FTDI driver.

Warning you take all responsibility for mucking with your system files. Know what you are doing and how to undo it before you proceed. We do not take any responsibility for issues arising from this.

Also, if you do not have any issues with your RTSystems FTDI cables, Chirp, Mavericks, and the FTDI OEM driver, then don't bother with this procedure.

This is a workaround only for people who have been having these issues.


  • stop using and unplug all FTDI usb adapters
  • unload existing FTDI OEM driver (if applicable):

    sudo kextunload -b com.FTDI.driver.FTDIUSBSerialDriver
  • Disable FTDI OEM driver (if applicable):

    sudo mv -v /System/Library/Extensions/FTDIUSBSerialDriver.kext/ /System/Library/Extensions/FTDIUSBSerialDriver.kext_disabled
  • check to see that there are no FTDI drivers loaded:

    kextstat |grep -i ftdi

    (should not show anything)
  • Add RTSystems VID/PIDs to Apple FTDI driver:

    sudo nano /System/Library/Extensions/IOUSBFamily.kext/Contents/PlugIns/AppleUSBFTDI.kext/Contents/Info.plist

    add following to IOKitPersonalities section:
  • plug in your rtsystems ftdi usb adapter
  • Force load of Apple FTDI driver:

    sudo kextload -b com.apple.driver.AppleUSBFTDI
  • verify Apple FTDI driver is loaded:

    kextstat |grep -i ftdi

    should be something like:

    129 0 0xffffff7f826d0000 0x7000 0x7000 com.apple.driver.AppleUSBFTDI (1.0.1b3) <77 36 5 4 3>
  • Verify Apple FTDI device node is created:

    ls -l /dev/cu.usbserial-*

    good result: should list a device file
    bad result: "no such file or directory"

you should now be able to use your adapter


You may need to repeat these steps if Apple updates FTDI driver (such as in a Combo Update aka Minor update release)