Operation Complete Query
The Operation Complete query places an ASCII character 1 into the device’s Output Queue when all pending device operations have been finished.
When a scenario is running there will be a pending operation set that is released at the start of each 100 ms epoch. As a consequence of this, an
*OPC? command will constantly block except for a short period at the start of each 100 msec epoch. The
OPC? command (and
*WAI command) can hence be used to synchronize the execution of other SCPI commands with GSG’s internal processing loop, with a resolution of 100 ms.
OPC? is the recommended method to synchronize commands as
*OPC? blocks at the user’s application, rather than within the GSG. The use of
*WAI is to be preferred, particularly if several consecutive commands are used as a means to count elapsed epochs.
For example, checking that the ECEF position command is applied on the next 10 Hz (100 ms) epoch: