What is the input range of APEX's trigger port?

APEX has a low-voltage TTL trigger input to receive up to 4 digital input signals.

The trigger interface is accessible via the Trigger connector on the top-left side of APEX shown in the figure below. It allows to acquire up to 4 digital input signals on the TRIGGER channel of APEX. Aside from logging events in the data stream, it is also possible to receive synchronization events from external hardware.

APEX trigger input

The trigger input is low-voltage TTL compatible and electrically isolated from the subject. The trigger channel employs negative logic for digital inputs, meaning that a high-voltage trigger input signal is registered as a low trigger value. Passive button presses are registered on the data stream as a high trigger value. Hence, when using a digital trigger generated, it is recommended to use a high-voltage TTL pulse as ‘base condition’, whilst using a low-voltage TTL pulse as ‘trigger event condition’.

The Recorder TRIGGER input channels have an input range of 0 to 3.3 V where:

  • A logic 'Low' is detected for input levels ≥ 2.0 V.
  • A logic 'High' is detected for input levels ≤ 0.8 V.


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