User manual

Command Sequence and Synchronization
R&S
®
Scope Rider RTH
242User Manual 1326.1578.02 ─ 04
Table B-1: Synchronization using *OPC, *OPC? and *WAI
Com-
mand
Action Programming the controller
*OPC Sets the Operation Complete bit in the ESR
after all previous commands have been exe-
cuted.
●
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 Oper-
ation 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.
*WAI Stops further command processing until all
commands sent before *WAI have been exe-
cuted.
Sending *WAI directly after the command
whose processing should be terminated
before other commands are executed.
Command synchronization using *WAI or *OPC? appended to an overlapped com-
mand 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 instrument 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.
Event Status Register (ESE)
1. Set the OPC mask bit (bit no. 0) in the ESE: *ESE 1
2. Send the overlapped command without *OPC, *OPC? or *WAI
3. Poll the operation complete state periodically (by means of a timer) using the
sequence: *OPC; *ESR?
A return value (LSB) of 1 indicates that the overlapped command has finished.
Preventing Overlapping Execution