Epson EQUITY 3865X/20 PLUS - Manual (Page 28)

Using the Serial Interface
If you have a printer, a modem, or other peripheral with a serial
interface, you can connect it to the serial (RS-232C) port on
the back of the computer.
The serial port uses a DB-9P connector, so be sure you have a
compatible cable. To connect a serial device, follow the same
steps as above for connecting a parallel device but insert the
connector into the serial port, marked with a special icon, as
shown below.
serial port
Note
You need to ensure that the serial port is set up so it functions
properly. If you are using the port for a serial printer, you need
to redirect printer output to the serial port instead of the
parallel port. To do this, you can use the MS-DOS MODE
or SETMODE command or the MENU utility. See your
MS-DOS Reference Manual for instructions.
Setting Up Your System
1-11