While trying to print an error message appears stating the port is in use and AppleTalk needs to be inactive. Trying to disable AppleTalk using the Control Strip or the Chooser does not disable AppleTalk.

Making AppleTalk Inactive

The default networking option for the Macintosh is to use the printer port for AppleTalk. In order to use the printer port for a serial device it is necessary to stop using the printer port for AppleTalk. There are two ways to accomplish this. The first is to move AppleTalk to another port such as Ethernet (if you are connected to an active Ethernet network). The second method is to make AppleTalk inactive.

During the migration from Classic Networking to Open Transport, older components of the networking software have not been upgraded to fully support Open Transport. Two such components are the Chooser and the AppleTalk Switch Control Strip Module. If AppleTalk is made inactive using either the Chooser or the Control Strip then only Classic AppleTalk components are made inactive. Open Transport AppleTalk components are still active. When you attempt to use the printer port for a serial device, the following error messages (or similar messages) may result:

"Printer port is in use by another application"
"Cannot find printer"
".[XXX printer driver] requires that AppleTalk is inactive. Please make AppleTalk inactive."

The recommended method of making AppleTalk inactive under Open Transport is to:

1. Open the AppleTalk control panel.
2. Select User Mode under the Edit menu (or Command-U).
3. Select Advanced user mode and click OK.
4. Click on the Options button.
5. Select Inactive and click OK.
6. Close the AppleTalk control panel.
7. Save the changes.