Serial Polling And Srq - Keithley 3700 series Reference Manual

Series 3700 System Switch/Multimeter Reference Manual
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Depending on how it is used, Bit B6 of the status byte register is either the request for service
(RQS) bit or the master summary status (MSS) bit; when using the GPIB serial poll sequence of
the Series 3700 to obtain the status byte (serial poll byte), B6 is the RQS bit. See
and SRQ
When using the *STB? common command or status.condition to read the status byte, B6
is the MSS bit.
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Serial polling and SRQ

Any enabled event summary bit that goes from 0 to 1 sets 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.
SRQs can be managed by the serial poll sequence of the Series 3700. 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.
For common and script commands, B6 is the MSS (message summary status) bit. The serial
poll does not clear MSS. The MSS bit stays set until all status byte summary bits are reset.
Document Number: 3700S-901-01 Rev. A / August 2007
Bit B0, measurement summary Bit (MSB): Set summary bit indicates that an enabled
measurement event has occurred.
Bit B1, system summary bit (SSB): Set summary bit indicates that an enabled system
event has occurred.
Bit B2, error available (EAV): Set bit indicates that an error or status message is
present in the error queue.
Bit B3, questionable summary bit (QSB): Set summary bit indicates that an enabled
questionable event has occurred.
Bit B4, message available (MAV): Set bit indicates that a response message is present
in the output queue.
Bit B5, event summary bit (ESB): Set summary bit indicates that an enabled standard
event has occurred.
Bit B6, request service (RQS)/Master Summary Status (MSS): Set bit indicates that
an enabled summary bit of the status byte register is set.
(on page 8-11) for details on using the serial poll sequence.
Bit B7, operation summary (OSB): Set summary bit indicates that an enabled
operation event has occurred.
Section 8: Status Model
Serial polling
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