Options (view menu), Options dialogue box, Serial cable, connecting – Meridian Audio 568 User Manual
Page 88: Serial port, specifying

Configuring the digital surround processor using a computer
81
To connect the serial cable
The serial cable is symmetrical, and can be connected either
way round.
●
Connect one end to the RS232 connector on the back panel
of the 568 Digital Surround Processor.
●
Connect the other end to one of the serial ports on the PC or
PC notebook computer.
Then specify the serial port you are using as follows:
●
Choose Options from the View menu to display the Options
dialogue box:
●
Select the port you want to use and click the OK button.