Functions of each connector pin Receive buffer full: When the remaining space in the receive buffer drops to 128 bytes, the printer status becomes "buffer full" and it remains "buffer full" until the space in the receive buffer increases to 256 bytes. The printer ignores the data received when the remaining space in the receive buffer is 0 byte. 64 DSUB9 Pin no. DSUB25 Pin no. Signal name Signal direction Function 1 — NC — Not connected 2 3 RXD Input Receive data 3 2 TXD Output Transmit data 4 20 DTR Output Indicates whether or not the printer power is ON. SPACE indicates that the printer power is ON, and MARK indicates that the printer power is OFF.
Indicates whether or not the printer is BUSY. SPACE indicates that the printer is ready to receive data, and MARK indicates that the printer is BUSY. The printer goes BUSY when the printer is made offline by pressing down the On/Off Line button or when the receive buffer is full. 5 7 GND — Signal ground 6 6 DSR Input Indicates whether or not the host computer power is ON. SPACE indicates that the host computer is ON, and MARK indicates that the host computer is OFF. Changing the setting of DIP switch or memory switch allows this signal to be used as a reset signal for the printer. This reset signal is used for detecting the MARK status of the host computer and for resetting the printer.
Indicates whether or not the host computer is ready to receive data. SPACE indicates that the host computer is ready to receive data, and MARK indicates that the host computer is not to ready to receive data. When DTR/DSR control is selected, check the status of this signal before transmitting data.