Waiting for Operation Complete
The *OPC command has a capability to wait for an operation to complete. Operation complete means that there is no pending operation that is still in progress. It takes approximately 330 ms on the PCR-M and approximately 110 ms on the PCR-LE/PCR-LE2 for a measurement to be completed. The PCR is not in the operation complete state while a measurement is ongoing. When the measurement completes, if there are no other operations waiting to be completed, the PCR enters the operation complete state.
When the *OPC command is sent, the PCR-M/ PCR-LE/PCR-LE2 enters the Operation Complete Command Active State (OCAS). When the measurement is completed and there is no other operation pending, the PCR-M/ PCR-LE/PCR-LE2 returns to Operation Complete Command Idle State (OCIS) and sets the OPC bit (bit 0) to TRUE (1) in the Standard Event Status Register. This information can be confirmed with the *ESR? query command by checking the OPC bit (bit 0).
The following example makes a new measurement and sends the *OPC. When the measurement is completed, an SRQ (Service Request) is generated, as the Standard Event Status Enable Register and the Service Request Enable Register are unmasked so that an SRQ can be signaled by the Operation Complete event. When using the RS232 interface, the SRQ feature cannot be used.
*ESE 1;*SRE 32;*CLS;:INITiate:IMMediate:SEQuence3;*OPC
<Wait for the SRQ to be generated.>
Using the *OPC? query command instead of the *OPC command makes the PCR-M/ PCR-LE/PCR-LE2 enter the Operation Complete Query Active State (OQAS). When the measurement is completed and there is no other operation pending, the PCR-M/ PCR-LE/PCR-LE20 returns to the Operation Complete Query Idle State (OQIS) and sets the response data to "1" (in NR1 format ) in the output queue.
<Read the response>
At power-on or after the IEEE488 sdc/dcl, *RST command is sent, the PCR-M/ PCR-LE/PCR-LE2 is in the OCIS and OQIS state