Chapter 2
Hardware Overview
GPIB-120B User Manual
2-4
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Setting the Data Transfer Mode
To use buffered mode, set the switch to the ON position, as shown in
Figure 2-2. To use unbuffered mode, set the switch to the OFF position.
Figure 2-2.
Switch Setting for Buffered Mode
Note
The placement of the switch to select buffered or unbuffered mode is recessed to
avoid unintentional toggling during operation of the GPIB-120B. To flip the switch,
a flathead screwdriver or similar tool may be required.
Verify that the switch on your GPIB isolator/expander is in the desired
position before powering on the unit.
Data Direction Control
Bus B sends the data lines to Bus A if the Bus B Source Handshake state is
true or if a Controller on Bus A is conducting a parallel poll.
Bus A sends the data lines to Bus B if the Bus A Source Handshake state is
true or if a Controller on Bus B is conducting a parallel poll.
Parallel Poll Detection
Controllers can conduct parallel polls on Bus A or Bus B, and devices on
both Bus A and Bus B can respond to parallel polls.
If a Controller on Bus A conducts a parallel poll, the parallel poll detection
circuitry on side B conducts a parallel poll on Bus B. The result of the
parallel poll is driven on the data lines of Bus A.
If a Controller on Bus B conducts a parallel poll, the parallel poll detection
circuitry on side A conducts a parallel poll on Bus A. The result of the
parallel poll is driven on the data lines of Bus B.
Refer to the
Parallel Poll Operation
section in this chapter for important
information about conducting parallel polls with the GPIB-120B.
ON
OFF
BUFFERED
