Chapter 3
Operation of the GPIB-232CV-A
3-6
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GPIB-232CV-A Serial Poll Responses
If the GPIB-232CV-A is serial polled, its response byte depends on the
status of the internal data buffers, as follows:
•
If the serial input buffer is empty, bit 1 of the status byte is set to 1.
•
If the serial input buffer is not empty, bit 1 is set to 0.
•
If the GPIB input buffer is empty, bit 0 of the status byte is set to 1.
•
If the GPIB input buffer is not empty, bit 0 is set to 0.
In all cases, bit 6 is set to 1 if the GPIB-232CV-A is requesting service;
otherwise it is set to 0.
GPIB-232CV-A Operation in Listen-Only Mode
In listen-only mode, no addressing is required to make the GPIB-232CV-A
a GPIB Listener and it cannot be unaddressed to listen. All data transferred
on the GPIB is accepted by the GPIB-232CV-A and output to the serial port
even if the data was intended for another device. This configuration can be
used to monitor all GPIB data bus activity. Notice that when the
GPIB-232CV-A is configured as a listen-only device, it cannot be serial
polled.
The GPIB primary address for the GPIB-232CV-A is specified by switches
1 through 5 of the DIP switch SW1. If GPIB address switches 1 through 5
are all set to ON, the GPIB-232CV-A is configured as a listen-only device.
Figure 3-4 shows the switch settings for listen-only mode.
Figure 3-4.
Switch Settings for Listen-Only Mode
SW1
MODE
CONFIG
GPIB ADDRESS
1 2 3 4 5 6 7 8
O
N
