Front-Panel Operation 2
Keysight 34420A User’s Guide 59
To Trigger the Meter
You can trigger the meter from the front panel using single trigger or autotrigger.
– Autotriggering is enabled when you turn on the meter. Notice that the 
* (sample) annunciator turns on during each measurement.
– Single triggering takes one reading each time you press   and then waits 
for the next trigger. Continue pressing this key to trigger the meter.
Using an External Trigger
The external trigger mode is also enabled by pressing  . It is like the single 
trigger mode except that you apply a trigger pulse to the rear-panel Ext Trig 
terminal. The meter is triggered on the negative edge of a TTL pulse. 
The front-panel   key is disabled when in remote.