Epson 500 Series - Manual (Page 52)

4. Connect the other end of the cable to the serial device. If the
connector has retaining screws, tighten them.
5. Connect the serial device's power cable (if it has one) to a
grounded electrical socket.
Check the documentation that came with your serial device to see
if any other steps are necessary.
Checking the Serial Port Settings
The COM1 port is capable of sending and receiving data at a
variety of speeds and with many different protocols. This means
you need to configure the port to match the signals of the serial
device. As a general rule, choose the highest speed (baud rate) and
the protocol that provides the best error detection.
Check the documentation that came with your serial device to see
if you need to adjust any of its settings.
Note
If your application program cannot send printer output directly
to the serial port, you can use the MS-DOS MODE command to
redirect the output. You can even tell the computer to redirect
printer and serial port settings automatically if you place the
appropriate MODE commands in your AUTOEXEC.BAT file.
See your MS-DOS manual for instructions.
Connecting Optional Devices 4-7