There are 4 trigger modes on U2815: INT, MAN, EXT and DUT.
When the trigger mode is set as INT, U2815 will make sequential and repeated tests.
When the trigger mode is set as MAN, press [TRIG] once, U2815 will make one test.
When the trigger mode is set as EXT, once the HANDLER interface receives a positive impulse, U2815 will execute one measurement.
When the trigger mode is set as DUT, once the test fixture receives a component, U2815 will execute one measurement.
When the trigger mode is set as BUS, once the IEEE 488 interface receives a TRIGGER command, U2815 will execute a test. The BUS mode cannot be set on the front panel.