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SERVICE REQUESTS
This appendix describes the analyzer service request (SRQ) capability and the use of service requests to interrupt
an HP-IB controller to obtain service. A service request is an analyzer output that tells the controller a specific event
has taken place in the analyzer. Service requests enable the analyzer to interrupt the controller program sequence,
causing the program to branch to a subroutine.
For example, by using service requests, the controller can perform other operations while the analyzer is sweeping,
and then service the analyzer when the sweep is completed. The analyzer sends its service request to the controller,
which triggers the controller to take action, such as changing the instrument state or reading data from the display
memory.
When making a service request, the analyzer places the HP-IB SRQ line true and the analyzer CRT display reads
out "SRQ" with a number. Setting the SRQ line true announces to the HP-IB controller that the analyzer requires
attention. The controller can then command the analyzer to send its "status byte". The status byte indicates the
type of service request.
If the CRT display annotation has been blanked, the service request notation will not
appear.
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3 2 A p p e n d i x
Appendix D
NOTE
DISPLAY DURING A SERVICE REQUEST
APPENDIX D
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