Quick Start How-to for using the USB to Serial Adapter / Converter.
Here are notes on using the USB - Serial Adapter / Converter on OS X 10.2.6.
As with most things, Apple made networking on OS X quick and easy. In the case of using this adapter, a bit too easy.
Removing the driver
System/Library/Extensions/ProlificUsbSerial.kext. (for Prolific based devices)
Note that to re-install the driver after it has been deleted, run the installer, and the reboot the Mac. Simply dragging the extension from the Trash back to the original location will not work.
When the USB - Serial Converter / Adapter is installed, OS X immediately makes the device available for the network drivers. Unfortunately, a network connection is commonly not what the adapter is being used for.
When the adapter is available to OS X for networking, the drivers will frequently check the device to see if there is a connection available that can be used by the network. This checking can (and usually will) cause problems for other software wanting to use the USB to Serial Adapter.
To configure OS X to prevent the network drivers from checking the USB to Serial device, perform the following.
Go to "System Preferences >> Network >> Show >> Network Port Configurations". Insure the usbserial adapter name in the "Port Configurations" list is not checked. If it has is checked, uncheck it then apply. Unfortunately there is a bug in 10.2.6 (Assigned Problem ID# :3429492) that prevents the apply from working, so the machine will need to be rebooted.
From the Apple menu select "System Preferences"
From the "System Preferences" menu on the "Internet & Network" section, select "Network". Depending on the prior state of this dialog, you will see the Network settings for one of the Network components. For example, The "AirPort" was last configured in the dialog shown below. If "Network Port Configurations" is not the current configuration, then select it using the "Show" choice as shown below.
Now insure the usbserial adapter name in the "Port Configurations" list is not checked as shown below. If it is checked, uncheck it then apply. Unfortunately there is a bug in OS X 10.2.6 that prevents the apply from properly working, so the machine will need to be rebooted. If this is not done your application may intermittently experience a 'port busy' error or 'Error: 16' when the port is opened.