The trigger port (black and blue banana jacks) can be used to connect to third-party timing devices to either receive or send timing impulses. These are a pair of standard 4mm banana plugs. 

Devices used to record impulses should be normally open and close the circuit to create the trigger, the impulse must be LOW for a duration of at least 1ms (0.001s). If recording multiple consecutive triggers, then the impulses must be 10ms apart (0.01s).

The trigger port cannot be used to connect a Loop Cable for timing.