*OPC?
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.
The OPC?
is the recommended method to synchronize commands as *OPC?
blocks at the user’s application, rather than within the GSG. The use of *OPC?
over *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:
sour:scen:ecefposition IMMEDIATE,1000.00,2000.00,3000.00
*OPC?
sour:scen:ecefposition?
Returned format
1