Epson TM-T20II Technical Reference Guide - Page 38

Connecting the Printer to the Host Computer  The printer uses a modular connector specifically designed for the cash drawer. Do not connect the connector to a telephone line.  For USB interface models, do not turn on the printer before installing the printer driver.  For Ethernet interface models, do not connect a telephone line or DK cable to the Ethernet connector. For Serial Interface Serial interface connection diagram When this printer is connected to a host computer by the serial interface, there are two connection methods; stand alone connection and pass-through connection. Stand alone connection This printer is connected to the host computer directly via the serial port. When a customer display (DM-D) is to be connected, connect it to the host computer via the serial port or USB port. DM-D (Serial I/F model) AC Adapter + AC cable Serial cable Extension cable for power supply TM-T20II Cash drawer Serial cable DK cable DM-D (USB I/F model) USB cable AC Adapter + AC cable TM-T20II Serial cable DK cable Cash drawer 38