Agilent Technologies Signal Analyzer N9030a - Manual (Page 106)

3 Programming the Analyzer
IEEE 488.2 Common Commands
Operation Complete
The *OPC command sets bit 0 in the standard event status register (SER) to “1” when pending
operations have finished, that is when all overlapped commands are complete. It does not hold off
subsequent operations. You can determine when the overlapped commands have completed either
by polling the OPC bit in SER, or by setting up the status system such that a service request
(SRQ) is asserted when the OPC bit is set.
The *OPC? query returns a “1” after all the current overlapped commands are complete. So it
holds off subsequent commands until the "1” is returned, then the program continues. This query
can be used to synchronize events of other instruments on the external bus.
Remote Command *OPC
*OPC?
Example INIT:CONT 0 Selects single sweeping.
INIT:IMM Initiates a sweep.
*OPC? Holds off any further commands until the sweep is complete.
Status Bits/OPC
dependencies Not global to all remote ports or front panel. *OPC only considers operation that was initiated on
the same port as the *OPC command was issued from.
*OPC is an overlapped command, but *OPC? is sequential.
Backwards Compatibility
Notes 1. The ESA/PSA/VSA products do not meet all the requirements for the *OPC command
specified by IEEE 488.2. This is corrected for X-Series. This will sometimes cause behavior that is
not backward compatible, but it will work as customers expect.
2. Commands such as, *OPC/*OPC?/*WAI/*RST used to be global. They considered front panel
operation in conjunction with the GPIB functionality. Now they are evaluated on a per channel
basis. That is, the various rear panel remote ports and the front panel i/o are all considered
separately. Only the functionality initiated on the port where the *OPC was sent, is considered
for its operation.
3. *OPC used to hold off until the operation bits were cleared. Now it holds off until all
overlapping commands are completed. Also, earlier instruments did not wait for completion of all
processes, only the ones identified here (in the STATus:OPERation register):
Calibrating: monitored by PSA, ESA, VSA (E4406A)
Sweeping: monitored by PSA, ESA, VSA (E4406A)
Waiting for Trigger: monitored by PSA, ESA, VSA (E4406A)
Measuring: monitored by PSA and ESA (but not in all Modes).
Paused: monitored by VSA (E4406A).
Printing: monitored by VSA (E4406A).
Mass memory busy: monitored by VSA (E4406A).
Initial S/W Revision Prior to A.02.00
106 Remote Language Compatibility Measurement Application Reference