The VectorStar VNA provides synchronization of the GPIB by executing commands in a serial fashion. Subsequent commands will not be parsed and executed until the current GPIB command is parsed and completely executed. Indeed, as far as VNA operations are concerned, if this serial execution method is not incorporated, the VNA, the GPIB bus, and the controller PC will be in chaos. Avoiding this chaos condition is so important that the IEEE488.2 standard mandated 3 commands to be provided: *OPC, *OPC?, and *WAI.

This synchronization is accomplished by the GPIB parser which waits for a Completed signal from the internal interface after starting execution of the command. While the parser is waiting, it is not parsing newer commands. Subsequent commands are put into the input buffer, awaiting their turn to be parsed and executed.