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Are Sealevel optically-isolated inputs active high or active low?
Reference Number: AA-00557 Views: 1780 Created: 03/05/2013 11:43 am Last Updated: 09/02/2016 05:30 pm 0 Rating/ Voters


It depends on how the input is wired to your application. An input is triggered when the input terminal and local common terminal of the Sealevel device detects a voltage difference greater than or equal to the input’s turn-on voltage – generally 3 VDC. The inputs are non-polarized so the voltage direction does not matter.

To wire an active high input, connect the local common terminal of the Sealevel device to the application Ground or negative voltage reference.

To wire an active low input, connect the local common terminal of the Sealevel device to the positive voltage reference.


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