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Serial Port Interface
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P1052685-001 GC420d™ User Guide 5/23/2012
Serial Port Interface
The maximum current available through the serial and/or parallel port is not to
exceed a total of 0.75 Amps.
When XON/XOFF handshaking is selected, data flow is controlled by the ASCII
control codes DC1 (XON) and DC3 (XOFF). The DTR control lead will have no
effect.
Interconnecting to DCE Devices — When the printer is connected via its RS-232
interface to data communication equipment (DCE) such as a modem, a Null
Modem RS-232 (straight-through) interface cable must be used. The figure below
shows the connections required for this cable.
Connecting to the KDU (Keyboard Display Unit) — The KDU was designed for
DCE printer connections (and does not require an adapter to communicate).
Connecting the Printer to a DCE Device
Pin Description
1 +5 V @ 0.75 A fused
2 TXD (transmit data) output from the printer
3 RXD (receive data) input to the printer
4 DSR (data set ready) input to the printer
5 Chassis ground
6 DTR (data terminal ready) output from the printer -- controls
when the host may send data
7 CTS (clear to send) - Not used by the printer
8 RTS (request to send) output from the printer -- always in the
ACTIVE condition when the printer is turned on
9 Not used
DB-9P
Connector
to Printer
DB-9P
Connector
to Printer
DB-25S
Connector
to DCE Device
DB-9S
Connector
to DCE Device