Agilent Technologies E3632A manual Using *STB? to Read the Status Byte

Chapter 4 Remote Interface Reference

The SCPI Status Registers

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.

Using *STB? to Read the Status Byte

The *STB? (Status Byte query) command is similar to a serial poll but it is processed like any other instrument command. The *STB? command returns the same result as a serial poll but the “request service” bit (bit 6) is not cleared.

The *STB? command is not handled automatically by the IEEE-488 bus interface hardware and will be executed only after previous commands have completed. Polling is not possible using the *STB? command. Executing the *STB? command does not clear the Status Byte summary register.

Using the Message Available Bit (MAV)

You can use the Status Byte “message available” bit (bit 4) to determine when data is available to read into your bus controller. The power supply subsequently clears bit 4 only after all messages have been read from the output buffer.

To Interrupt Your Bus Controller Using SRQ

1Send a device clear message to clear the power supply’s output buffer (e.g.,

CLEAR 705).

2Clear the event registers with the *CLS (clear status) command.

3Set up the enable register masks. Execute the *ESE command to set up the Standard Event register and the *SRE command for the Status Byte.

4Send the *OPC? (operation complete query) command and enter the result to ensure synchronization.

5Enable your bus controller’s IEEE-488 SRQ interrupt.

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