Programming in G Mode
Chapter 7
GPIB-610 User Manual
7-4
© National Instruments Corp.
When the GPIB-232CT receives its own address, the data it receives is
referred to as programming messages; the data it sends is referred to as
status information.
The GPIB-232CT and Serial Device as Listener
When the GPIB-232CT receives its own listen address, it examines the data
received over the GPIB, treats it as a programming message or messages,
and takes actions based on that data.
When the GPIB-232CT receives the serial device listen address, it forwards
the data received over the GPIB to the serial port without examining the
data for meaning.
For example, let's say you have a serial printer connected to the
GPIB-232CT and you wish to send a data file from your computer over the
GPIB to the printer. Ordinarily, when the printer buffer is full, the printer
sends the XOFF character; when the printer is ready to receive more
characters, it sends the XON character. So, before you send your file to the
printer, you must tell the GPIB-232CT to watch for XON/XOFF characters
from the printer.
Do this by first addressing the GPIB-232CT to listen by sending its listen
address. Then, send it the programming message
xon ,1
. The
GPIB-232CT interprets this programming message and acts upon it without
sending any data on to the serial device.
Next, address the serial device to listen by sending to the GPIB-232CT the
serial device listen address. Then, send the data over the GPIB. The
GPIB-232CT sends that data on to the printer without examining that data
for meaning. The LISTEN LED on the GPIB-232CT front panel is lit when
either the GPIB-232CT is addressed to listen or the serial device is
addressed to listen.
