Appendix Functions of each connector pin 85 Pin no. Signal name Signal direction Function 2 RXD Input Reception data 3 TXD Output Transmission data 4 DTR Output 1) When DTR/DSR control is selected, this signal indicates whether the printer is BUSY. • SPACE status Indicates that the printer is ready to receive data. • MARK status Indicates that the printer is BUSY. Set BUSY conditions with the memory switch. 2) When XON/XOFF control is selected, the signal indicates that the printer is properly connected and ready to receive data from the host. The signal is always SPACE, except in the following cases:
• During the period from when power is turned on to when the printer is ready to receive data. • During the self-test. 5 SG — Signal ground 6 DSR Input This signal indicates whether the host computer can receive data. SPACE indicates that the host computer can receive data. MARK indicates that the host computer cannot receive data. When DTR/DSR control is selected, the printer transmits data after confirming this signal (except if transmitted using some ESC/POS commands). When XON/XOFF control is selected, the printer does not check this signal. 7 RTS Output Equivalent to DTR signal (pin 4)