How do I run serial devices from a Mac which has only USB ports?

Technical Note: 11
Reads: 6389
Creation Date: 28/09/1999
Modification Date: 26/07/2005

Improvision recommends USB serial adapters from Keyspan.

The USA28X USB serial adapter provides two serial ports numbered from one USB port and is suitable for connecting Mac serial cables. Devices may be plugged into either or both ports.

The USA49W serial adapter provides four serial ports from one USB port and is suitable for connecting PC (9 pin D) serial cables.

To use these adapter the drivers must be loaded. Drivers are available from Keyspan for both Mac OS 9 and X. The latest drivers can be found on Keyspan's website here.