Unisys E-@CTION EFP9800 - Manual (Page 84)

Communication
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DTR/DSR Protocol
The DTR signal is used to control data transmission to the printer. It is driven
low when the printer is ready to receive data and driven high when it cannot
accept any more data. Data is transmitted from the printer after it confirms that
the DSR signal is low.
RS-232C Interface Connectors
This section describes the pin settings for the RS-232C connectors and interface
parameters. The RS-232C parameters are selected by setting the DIP switches
on the PC board. For more information, see “Setting Switches” later in this
section. The RS-232C parameters must match those of the host computer.
RS-232C Communication Connector Pin Assignments
The following illustrations show the RS-232C communication connector and pin
assignments. The connector is a 9-pin male D-shell connector and is located at
the rear of the printer.
RS-232C 9-Pin to 9-Pin Communication Connector Pin Assignments