If you have worked through the other section in this series, you have probably come to realize that, in addition to exchanging data, you need control when the exchange takes place. You may need to synchronize the instrument with your program execution or provide a means for the instrument to signal your program. This section describes three ways to synchronize your program with your instruments.

  • The first method is to stop the executing of the Visual Basic code with a *OPC? Command. When the instrument has finished executing the commands that have been received it will become idle and respond to the *OPC? Command.
  • The second method is to have the instrument interrupt the execution of the Visual Basic program with an SRQ. The GPIB bus includes a SRQ line, a hardware line that connects the instrument to the computer.
  • The third method is to use Visual Basic to poll the instrument's SRQ status register.

Note: This section illustrates the use of instruments that support the SCPI and IEEE-488.2 Common Commands. For older, non-SCPI instruments, consult the instrument documentation.

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