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13803 Appendix A System Interface Description
A-1 A-2
Appendix A System Interface Description 1 Serial Interface RS-232C
There are two system interfaces:
- one RS-232C serial interface
- one Parallel Centronics interface.
The interfaces can be operated in three different modes:
- serial interface active
- parallel interface active
- both interfaces active in shared mode
The following chapter gives an overview about interface characteristics, control
signals, protocols, and cabling.
Any change of the operation mode (Serial, Parallel or Shared) and of the size of
the interface buffer is possible only when the interface buffer is completely
empty of data.
Display messages: READY 4 ELQ , BUSY 4 ELQ, or LOCAL.
Interface Characteristics
Signal Description Pin No. Direction
PG Protective Ground 1 -
TXD Transmit Data (from printer to host) 2 OUTPUT
RXD Receive Data (from host to printer) 3 INPUT
RTS Request to Send (printer is ready to send data) *) 4 OUTPUT
CTS Clear to Send (host is ready to receive data) *) 5 INPUT
DSR Data Set Ready 6 INPUT
SG Signal Ground 7 -
DTR Data Terminal Ready (printer is ready to receive - see also on the 20 OUTPUT
following pages the data communication protocols for detail mean-
ing)
*) with internal pull-up
- Transmission rate: 600, 1200, 2400, 4800, 9600, or 19200 baud
- Parity: even, odd, none, or ignore
- Word length: 7, or 8 bits
- Number of stop bits: In receive mode the printer accepts 1, or 2 stop bits. The
printer transmits always two stop bits.
Transmission Protocols:
- DTR - Ready/Busy
- XON/XOFF
- XON/XOFF + DTR