The external trigger settings are defined within a “Custom Triggers” measurement profile. These settings are shown conceptually here:
The Custom Triggers measurement profile looks like this:
External Trigger measurements can be performed using either of two basic methods:
Set the Clock Source to “Internal” and use the external trigger to control the start and stop of a scan at a give rate.
Set the Clock Source to “External” and trigger measurements exclusively with the external trigger.
Clock Source:
Internal (Internal Clock with External Start/Stop Signal). Measurements will be triggered by the external start/stop signal on the trigger board. However, the measurement rate will be taken based on internal settings and is not synchronized to an external signal.
External (External Clock with Start/Stop Signal). The measurement will be controlled by a start/stop signal on the trigger board. One transition of the clock signal (positive or negative depends on the configuration) triggers a measurement if the Start/Stop signal is active.
Start / Stop Active Level
Low/High. The start/stop signal can be set either low or high active (for example, low active means that events are being generated as long as the start/stop signal remains low).
Start / Stop Source
Ignored/Active. This setting controls the subsequent response to the external trigger after a measurement operation has started. If ignored, the measurement will continue regardless of other triggers until the profile is stopped, while if active, the following trigger changes will start / stop the measurement.
Clock Transmission
Negative/Positive. This defines the change in clock signal used for the trigger (negative transition or positive transition).
Minimal Time Delay
Delay Value. This defines the maximum rate at which mea- surements can be taken (minimal delay between two consecu- tive measurements). Additional trigger signals sent faster than this preset delay will be ignored.