Chapter 4 Remote Interface Reference
The SCPI Status Registers
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Caution 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 s a me r e s ul t a s a s e r ia l p ol l b u t t h e “r e q u es t s er v i c e” b i t ( b i t 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 SRQ1Send 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? (operat ion com ple te q uer y) c omm and and ent er t he r esu lt t o
ensure synchronization.
5Enable your bus controller’s IEEE-488 SRQ interrupt.