Keyspan USA-19 - Manual (Page 5)

Note: If you are a developer and need more information about using Mac OS X serial
ports, please visit our Developer web page at:
<http://www.keyspan.com/support/developers/>
Using the Keyspan Serial Assistant application, you see which Keyspan serial ports have been
added to Mac OS X. This is useful in determining which port to select in your serial device's
software.
Please note, the POSIX API is unique to Mac OS X and cannot be used by 'classic' applications.
Mac OS X vs CLASSIC
Since both Mac OS X and the Classic environment have the ability to use USB devices directly, you
may run into a case where you have installed the USB Serial Adapter software for Mac OS X as
well as the 'classic' USB Serial Adapter software. At this point, you have two software drivers for
one hardware device.
In these cases, Mac OS X will allow you to use BOTH the 'classic' Keyspan drivers as well as the
Mac OS X Keyspan drivers. However there are certain rules regarding which operating system has
access to the ports...
1. if your 'classic' Mac OS has opened the Keyspan serial port(s) or is sending data to
it, the Keyspan device and its serial port(s) will appear as 'busy' or 'in use' to any
application requesting the Keyspan device in Mac OS X.
2. if Mac OS X has opened the Keyspan serial port(s) or is sending data to it, the
Keyspan device will appear as if it is not connected (or unplugged) in your 'classic'
Mac OS and any application requesting the Keyspan serial ports (in the 'classic'
Mac OS) will get an error or report that the serial port is not available.
Exception: if you are using Virtual PC's 'USB' emulation setting, neither Mac OS X or
your 'classic' Mac OS will have access to the Keyspan device. If you use Virtual PC's
COM port emulation both of the above rules apply depending on whether you run Virtual
PC in Mac OS X or CLASSIC. Please see Virtual PC's documentation for more details
regarding USB and COM port emulation.
Keyspan:USB Serial Adapter for Mac OS X-v2.x User Manual
This User Manual applies to the Keyspan USB Serial Adapter Software for Mac OS X.
Rev 05jul15 Page 5