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7 Digital Communications Interface
Remote communications allows an external device, such as a computer, to com
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municate with the 1504 to obtain measurement data and control its operation.
Communication is accomplished with various commands issued to the 1504
through the RS-232 port or optional IEEE-488 port. A full list of commands is
given in Section7.3.
7.1 Serial Interface
The 1504 is equipped with an RS-232 serial port. The RS-232 interface is use
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ful for connecting the 1504 to most any microcomputer. The RS-232 socket is
located on the back panel of the 1504. Wiring of the interface cable should be
as shown in Figure 6 below. To eliminate noise, the serial cable should be
shielded with low resistance be
-
tween the connector (DB-9) and
the shield. The protocol for
RS-232 communications is 8
data bits, 1 stop bit, and no par-
ity. The RS-232 interface uses
RTS and CTS for flow control.
7.1.1 Setting the Baud Rate
The 1504 must be set to the
same baud rate as the remote
device. The baud rate of the
1504 can be set to 1200, 2400,
4800, or 9600. The default is
2400. The baud rate is set in the
Comm menu. Press the Menu
button (“SEt?” appears) then
press the K/Comm button. The
display will briefly indicate
“SErIAL”, then “bAUd”and
then display the current baud
rate. Use the U and D buttons
to increase or decrease the baud
rate then press Enter. The next
parameter in the Comm menu,
the serial sample period, will
then appear.
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7 Digital Communications Interface
Serial Interface
Figure 6 Serial Cable Wiring