Handshaking
The printer’s serial interface can use DTR (Data Terminal R eady) signal
levels and XON/XOFF communication protocols either separately or in
combination. When the vacant area for data in the input buff er drops to
256 bytes, the printer outputs an XOFF code or sets the DTR signal level to
low (MARK), indicating that it cannot receive more data.
Once the vacant area for data in the buffer recovers to 512 byte s, the
printer outputs the XON code or sets the DTR flag to high (SPACE),
indicating that it is again ready to receive data.
Error handling
A * character is printed if a parity error, framing error, or overrun error is
detected.
Pin assignments
The serial interface connector pin assignments and a description of the
interface signals are shown in the table below. The direction of signals is
given as viewed from the printer.
Signal
pin RS-232C Direction Description
2 TXD OUT Transmits data. This pin
transmits serial data from the
printer to the computer.
3 RXD IN R eceived data. This p in
transmits data from the
computer to the printer.
4 RTS Always +12V
5 CTS IN Always ignored
6 DSR IN Data set ready.
7 Signal ground
R
Ktwk Rev.C
A5 size Appendix A
97/12/26 pass 0

Technical Specifications A-13