User`s manual

112 Chapter 5

O:\Manuals\E6380A_Progguid\Book\Trigmeas.fm

Triggering Measurements

Arming Hardware-Triggered Measurements

Some measurements 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.

NOTE

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 HP-IB 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.