Agilent Technologies A.18.00 User Manual

Measurement pacing can be accomplished by using the IEEE 488.2-1987 
Common Commands *OPC, *OPC?, and *WAI. These commands are 
implemented within the Test Set using the criteria that an operation has not 
completed until 

•

all active measurements have obtained at least one valid measurement result 

•

all signals generated by the Test Set are within specifications. 

Refer to the 

 and the 

IEEE 488.2-1987 Standard for more information on using these commands. 

Some measurements, such as the Tone Sequence Decoder, require an external 
signal to trigger the measurement. These measurements require that the 
measurement be “armed” in order for it to be triggered by the external signal. The 
:TRIGger:IMMediate command is used to arm these types of measurements 
within the Test Set. 

When the trigger mode is set to RETRigger SINGle, the measurement must be 
re-armed after each measurement cycle. 

When the trigger mode is set to RETRigger REPetitive, the measurement is 
continually re-armed after each measurement cycle. 

Bus Lock Up: If the required triggering signal is not received, or if the signal level 
is incorrect, the measurement will not trigger and the measurement cycle will not 
complete. If a measurement cycle does not successfully obtain a valid 
measurement result, it will continue to try until it does (an external trigger is 
detected) or until the measurement trigger is aborted. This is true for both 
retriggering modes. This has the consequence that both the GPIB bus and the 
Active Controller handshake are in a temporary holdoff state while the Active 
Controller waits to read the measurement result from the Test Set. 

The control program should include measurement time-out routines that CLEAR 
the bus and ABORt the trigger if a measurement does not complete within a 
specified amount of time. This provides a method of preventing the bus from 
remaining in the temporary holdoff state indefinitely.