The first step is to deactivate all software that is or could be communicating through the serial port to its device. This is to prevent two pieces of software from trying to use the same port at the same time which may cause the Mac to freeze.
  Install Port Juggler Software
Insert the Port Juggler disk. Open the Port Juggler folder and drag the Port Juggler icons into the System folder in your hard disk*.
*Refer to the "Installation" Chapter to determine which Port Juggler files to use.
  Configure the Port Trigger List & Shutdown
Open the Chooser and assign the devices you are going to connect to
the Port Juggler hardware to the Port Trigger List. Shutdown your Mac.
  Configure Hardware & Restart
Configure the hardware to match what you assigned to the Port Trigger List. Restart your Mac.
  Configure Devices’ Software
Go into each of the devices’ software and configure the port settings to match the Macintosh port that they are connected to.
  Reactivate Devices’ Software
Now you can reactivate the software that was deactivated and rock n roll.
