Agilent Technologies E3633A, E3634A manual Using Service Request SRQ and Serial POLL

Chapter 4 Remote Interface Reference

The SCPI Status Registers

The Status Byte Summary register is cleared when:

•You execute the *CLS (clear status) command.

•Querying the Standard Event register (*ESR? command) will clear only bit 5 in the Status Byte summary register.

For example, 24 (8 + 16) is returned when you have queried the status of the Status Byte register, QUES and MAV conditions have occurred.

The Status Byte Enable register (Request Service) is cleared when:

•You execute the *SRE 0 command.

•You turn on the power and have previously configured the power supply using the *PSC 1 command.

•The enable register will not be cleared at power-on if you have previously configured the power supply using *PSC 0.

	Using Service Request (SRQ) and Serial POLL
	You must configure your bus controller to respond to the IEEE-488 service
	request (SRQ) interrupt to use this capability. Use the Status Byte enable
	register (*SRE command) to select which summary bits will set the low-level
	IEEE-488 service request signal. When bit 6 (request service) is set in the Status
	Byte, an IEEE-488 service request interrupt message is automatically sent to
	the bus controller. The bus controller may then poll the instruments on the bus
	to identify which one requested service (the instrument with bit 6 set in its
	Status Byte).
	The request service bit is cleared only by reading the Status Byte using an
	IEEE-488 serial poll or by reading the event register whose summary bit is
	causing the service request.
	To read the Status Byte summary register, send the IEEE-488 serial poll
	message. Querying the summary register will return a decimal value which
	corresponds to the binary-weighted sum of the bits set in the register. Serial
	poll will automatically clear the “request service” bit in the Status Byte
	summary register. No other bits are affected. Performing a serial poll will not
	affect instrument throughput.
C a u t i o n	The IEEE-488 standard does not ensure synchronization between your bus controller
	program and the instrument. Use the *OPC? command to guarantee that commands
	previously sent to the instrument have completed. Executing a serial poll before a
	*RST, *CLS, or other commands have completed can cause previous conditions
	to be reported.
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