D-14 Status Model Series 2600 System SourceMeters Reference Manual
2600S-901-01 Rev. A / May 2006 Return to Appendix D topics
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.
SRQs can be managed by the serial poll sequence of the SourceMeter. 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.
SPE, SPD (serial polling)
For the GPIB interface only, the SPE, SPD General Bus Command sequence is
used to serial poll the SourceMeter (see “
General bus commands” in Section 11).
Serial polling obtains the serial poll byte (status byte). Typically, serial polling is
used by the controller to determine which of several instruments has requested
service with the SRQ line.
Status byte and service request commands
The commands to program and read the Status Byte Register and Service
Request Enable Register are listed in
Table D-3. Note that the table includes both
common commands and their script command equivalents. For details on
programming and reading registers, see “
Programming enable and transition reg-
isters” and “Reading registers” in this appendix.
To reset the bits of the Service Request Enable Register to 0, use 0 as the
parameter value for the command (for example, *SRE 0).
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