Keithley 7999-6, Инструкция по эксплуатации

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Operation 3-15
Serial polling and SRQ
Any enabled event summary bit that goes from 0 to 1 will set bit B6 and generate an SRQ
(service request). In your test program, you can periodically read the status byte to check if an
SRQ has occurred and what caused it. If an SRQ occurs, the program can, for example, branch
to an appropriate subroutine that will service the request.
Typically, SRQs are managed by the serial poll sequence of the relay unit. If an SRQ does
not occur, bit B6 (RQS) of the status byte register will remain cleared, and the program will
simply proceed normally after the serial poll is performed. If an SRQ does occur, bit B6 of the
status byte register will set, and the program can branch to a service subroutine when the SRQ
is detected by the serial poll.
The serial poll automatically resets RQS of the status byte register. This allows subsequent
serial polls to monitor bit B6 for an SRQ occurrence generated by other event types. After a
serial poll, the same event can cause another SRQ, even if the event register that caused the first
SRQ has not been cleared.
The serial poll does not clear MSS. The MSS bit stays set until all status byte summary bits
are reset.
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