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Shutter Open and Closed Sensor Magnet Positioning

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Tim Long edited this page Jun 12, 2020 · 3 revisions

Shutter Open and Closed Sensor Positioning

Correct operation of the shutter relies on careful positioning of the Open/Close sensor magnets. Some experimentation may be needed to get the position just right.

The aim is to place the magnet as close to the end of travel as possible, so that the shutter just stops a hair short of the end of travel, but not so far that it "crashes" into the physical limit of travel.

What we want to avoid is placing the magnet too high (for close) or too low (for open). In this situation, there is a risk that the shutter can be moved fully past the detection zone of the limit sensor. When the shutter is moved back in the other direction later, the limit switch will close again and the controller will see this and stop the motor, and that's probably not what we want.

  • If, after closing the shutter using software, there is a gap and you feel the need to close the shutter even further using manual controls, then that's probably a sign that you need to lower your close sensor magnet a bit.

  • If the shutter doesn't open far enough, you may need to raise the open sensor magnet a little.

  • If your shutter takes two tries to open - you issue the open command and the shutter moves a short distance then stops, but opens fully on the second try - then you probably need to lower your close sensor magnet a bit.

  • If the shutter "crashes" into the end of travel, then you've gone too far and need to move the magnet away from the end of travel a little bit.

When adjusting, it may be best to start with the magnet deliberately too far away from the end of travel, then adjust in small amounts, testing after each adjustment, until the shutter stops in the position where you are happy with it. Get your Close sensor working right first, because this establishes the zero position from which the open position is measured.

Note: If the shutter does "crash" into the end of travel, the motor may stall with a horrible grinding sound. It sounds pretty bad but in fact it is not really harmful to the motor or electronics, so don't worry too much. Your adjustment should not allow this to happen on a regular basis though, because it would over time introduce excessive wear and tear on the mechanical components and possibly the structure.

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