Connecting The Rs-232-Cinterface - HP 7470A Interfacing And Programming Manual

Operation
The rear-panel switch labeled Y/D should be set to D.If it is set to Y,the
plotter must receive a plotter on instruction, ESC . ( or ESC . Y, before
it will respond to other commands from the terminal. The terminal
should be set to half duplex in order to Viewthe characters being sent
to the plotter. Plotter output will be displayed on the terminal. The
following diagram shows plotter operation when in the programmed-on
state in a terminal—onlyenvironment.
TERMINAL
IN
HALF
DUPLEX
PLOTTER
4'
OUTPUT
PLOTTER
INSTRUCTTONS
Terminal-only Environment, Programmed On
Connecting the RS-232-CInterface
The 7470 plotter interfaces to the RS-232-C communications lines
through a standard 25-pinfemale connector mounted on the back of the
plotter. The 7470 is capable of operating in a three—wire(transmit,
receive, ground) configuration.
In hardwired handshake operation, the Data Terminal Ready line (pin
20 of the connector on the plotter) is used to monitor the space in the
buffer available for input. The plotter outputs data when requested
(refer to Hardwire Handshake in this chapter).
If you are fabricating the cable assembly, the connector should be a
25-pin type "D" subminiature CINCH DBC—25P plug or equivalent.
Connector pin allocations for the three—wire c onfiguration are identified
and described in the following table.
10-10 RS-232-C/CCITT V.24INTERFACING