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Application Note

How -to Guide: Use an Open Collector Output

Many Gill level sensors come with a secondary output function which operates as a high or low level switch.

So what is it and how do I use an Open Collector switch output?

Many of the latest Gill liquid level sensors have an in-built secondary output function (this includes LevelPro, LevelSlick and non-temperature optioned LevelLite sensors), which operates as a high or low level switch (or both when programmed appropriately). This is implemented using an electronic switch known as an ‘open collector’.

So what is this and how can it be used?

Essentially, the level sensor has an on-board electronic switch (a Metal-Oxide-Semiconductor Field-Effect Transistor or MOSFET). This simulates a switch and can be thought of as a set of relay contacts. The switch can be set-up to open or close at a given liquid level by using the GS Level configuration tool, available for download from our website.

When combined with other components, the Open Collector Output can be used to drive LEDs, indicators, small pumps or relays (to operate larger pumps). Alternatively, the switch can drive an input to a controller such as a PLC or a computer board such as a Raspberry PI or an Arduino (please see instructions of the PLC/computer on how to set the input measurement).

There are a few restrictions using the electronic switch:

  • One side of the switch is connected to the sensor ground wire.
  • There is a maximum voltage of 50V and a maximum current of 0.5A.

Driving an LED indicator or opto-isolator.

Download full guide below. 

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