Chapter 4 Remote Interface Reference
The SCPI Status Registers
107
4
To Determine When a Command Sequence is Completed
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.
3Enable the “operation complete” bit (bit 0) in the Standard Event register by
executing the *ESE 1 command.
4Send the *OPC? (operation complete query) command and enter the result to
ensure synchronization.
5Execute your command string to program the desired configuration, and then
execute the *OPC (operation complete) command as the last command. When
the command sequence is completed, the “operation complete” bit (bit 0) is
set in the Standard Event register.
6Use a serial poll to check to see when bit 5 (standard event) is set in the Status
Byte summary register. You could also configure the power supply for an SRQ
interrupt by sending *SRE 32 (Status Byte enable register, bit 5).
Using *OPC to Signal When Data is in the Output Buffer
Generally, it is best to use the “operation complete” bit (bit 0) in the Standard
Event register to signal when a command sequence is completed. This bit is
set in the register after an *OPC command has been executed. If you send
*OPC after a command which loads a message in the power supply’s output
buffer (query data), you can use the “operation complete” bit to determine
when the message is available. However, if too many messages are generated
before the *OPC command executes (sequentially), the output buffer will fill
and the power supply will stop processing commands.