Epson ActionNote - Manual (Page 80)

2. Connect the serial cable to the COM 1 port.
3. If the connector has retaining screws, tighten them.
4. Connect the other end of the cable to the serial device.
5. If the serial device has a power cable, connect it to a
grounded (earthed) electrical socket.
Check the documentation that came with your serial device to
see if any other steps are necessary.
5-6 Connecting Optional Devices