Rohde & Schwarz SMC100A - Page 195

R&S SMC100A Instrument Model and Command Processing
1411.4060.32 5.22 E-1
Command Synchronization
In order to prevent an overlapped execution of commands, one of commands *OPC, *OPC? or *WAI
can be used. All three commands cause a certain action only to be carried out after the hardware has
been set and has settled. By suitable programming, the controller can be forced to wait for the
r
espective action to occur (see table).
Synchronization with *OPC, *OPC? and *WAI
Command Action Programming the controller
*OPC Sets the Operation Complete bit in the ESR
after all previous commands have been
executed.
- Setting bit 0 in the ESE
- Setting bit 5 in the SRE
- Waiting for service request (SRQ)
*OPC? Stops command processing until 1 is
returned. This is only the case after the
Operation Complete bit has been set in the
ESR. This bit indicates that the previous
setting has been completed.
Sending *OPC? directly after the command whose
processing should be terminated before other commands
can be executed.
Disabling bit 4 (MAV) of the SRE register.
Alternative: Service request or timeout method with enabled
MAV bit; see below.
*WAI Stops further command processing until all
commands sent before *WAI have been
executed.
Note: While waiting it is still possible to send
messages to the device.
Sending *WAI directly after the command whose processing
should be terminated before other commands are executed.
Command synchronization by means of a *WAI or *OPC? appended to an overlapped command is a
good choice if the overlapped command takes only little time to process. The two synchronization
techniques simply block overlapped execution of the command.
For time consuming overlapped commands it is usually desirable to allow the controller or the R&S
signal generator to do other useful work while waiting for command execution. Use one of the following
methods:
*OPC with a service request
1. Set the OPC mask bit (bit no. 0) in the ESE: *ESE 1
2. Set bit no. 5 in the SRE: *SRE 32 to enable ESB service request.
3. Send the overlapped command with *OPC
4. Wait for a service request
The service request indicates that the overlapped command has finished.
*OPC? with a service request
1. Set bit no. 4 in the SRE: *SRE 16 to enable MAV service request.
2. Send the overlapped command with *OPC?
3. Wait for a service request
The service request indicates that the overlapped command has finished.