Agilent Technologies N1911A Programming Manual page 774

17 IEEE 488.2 Command Reference
*OPC
The *OPC (OPeration Complete) command causes the power meter to set
the operation complete bit in the Standard Event Status Register when all
pending device operations have completed.
Syntax
Query
*OPC?
The query places an ASCII 1 in the output queue when all pending device
operations have completed.
746
*OPC
?
N1911A/1912A P-Series Power Meters Programming Guide