10 Z4Mplus and Z6Mplus Maintenance Manual 13358L Rev. 1 11/17/03
Section 1 System Description
Communication Buffer
The printers have a communication buffer that stores the incoming data until that
information can be acted upon (imaged). Communication handshaking (DTR/DSR control
signals or XON/XOFF control codes) controls when the host can send data to the printer.
The size of the buffer is 5000 characters. As the printer receives data, the processor
monitors the number of characters in the buffer. If the buffer is filled beyond 4744
characters, the printer will turn DTR; off (negative voltage) or transmit an XOFF (DC-3)
control character to the host. When the buffer empties below 4250 characters, the printer
will turn DTR; on (positive voltage) or transmit an XON (DC-1) control character to the
host.
Standard Serial Communication Connector
The connection for this standard interface is made through the female DB-9 connector on
the rear panel of the printer. A DB-9 to DB-25 interface module is required for all RS-232
connections through a DB-25 cable (see page 13 for details).
For all RS-232 input and output signals, the printer follows both the Electronics Industries
Association’s (EIA) RS-232 specifications and the Consultative Committee for
International Telegraph and Telephone (CCITT) V.24 standard signal level specifications.
Table B-1 shows the pin configuration and function of the rear panel serial data connector
on the printer.
Table 1-3. Serial Port Pin Configuration
Pin No. Name Description
1 — Not connected
2 RXD Receive data—data input to printer
3 TXD Transmit data—data output from printer
4 DTR Data terminal ready—output from printer
5 SG Signal ground
6 DSR Data set ready—input to printer
7 RTS Request to send—output from printer
8 CTS Clear to send—input to printer
9 +5 V DC +5 VDC signal output
Note • This pin is also available as a +5 VDC power source at 750 mA. To enable this
capability, a jumper on the computer’s main logic board needs to be installed on JP1,
pins 2 and 3.
Note • An interface module is required for RS-422/RS-485 interface support (see page
14).
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