Epson PLQ-20 Reference Manual page 83

Auto I/F wait time (Seconds)
When the printer is in the auto interface mode and it receives no
data from the currently selected interface for the amount of time
specified with this setting, it determines which interface is
receiving data and switches to that interface. You can specify
either 10 or 30 for the auto interface wait time. When the printer
turns on in the PR2 mode, this mode is not activated.
Parallel I/F bidirectional mode
The Parallel Interface bidirectional transfer mode is used when
this feature is set to On. If bidirectional transfer mode is
unnecessary, select Off.
Packet mode
Make sure to select Auto when you print from Windows
applications using the printer driver included on the User
CD-ROM. Set this feature to Off if you have connection troubles
while printing from applications based on other operating
systems such as DOS. When the printer turns on in the PR2 mode,
this mode is set to Off.
Baud rate (bps)
Use this option to set the data transfer rate (baud) for the serial
interface. The baud rate is measured in bits per second (bps).
Data length (bit)
Set the data length of the serial interface to 7 or 8.
Parity
When this option is set to None, parity checking is disabled. The
parity bit, if used, provides a basic form of error detection.
Chapter 5 Control Panel 83