Epson DM-D500 Technical Reference Guide - Page 66

DP-501 The connectors on the DP-501 are as indicated below. Connector for computer connection DM-D connector Connector for printer connection Connector for power supply unit connection Connector for power extension cable connection Connector for computer connection This is the connector for connecting to a computer.   Pin assignments Pin Number Signal Name 1 FG 2 TXD 3 RXD 4 (*1) RTS 6 (*2) DSR 7 20 (*1) GND DTR 25 RESET   Signal Direction Signal Function - Frame ground Output (1) In a pass-through or Y connection, data sent from the printer to the host (2) In a stand-alone connection, data sent from the display to the host Input Data received from the host (Host -> display) Output Same signal as DTR. Input Indicates whether or not the host is ready to receive data. [SPACE] The host is ready to receive data [MARK] The host is not ready to receive data - Signal GND Output Indicates whether or not the display is ready to receive data. (*2) [MARK] The display is not ready to receive data The display enters the MARK status in the following cases: (1) During power-on initialization (2) During self-test (3) The empty capacity of the receive buffer is 128 bytes or less (4) When DSR enters the MARK status on printer selection [SPACE] The display is ready to receive data The display enters the SPACE status in the following cases: (1) When power-on initialization finishes (2) When self-test finishes (3) When the empty capacity of the receive buffer recovers to 256 bytes or more from 128 bytes or less Input Reset signal for the printer (*1) Make sure to use either the RTS or the DTR terminal. Otherwise, the built-in RS-232 driver IC may be broken. (*2) This signal is connected to the DTR terminal of the printer directly. 66