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View Full Version : Two encoders on one BU0863X input ?



spitfire9
12-17-2010, 12:28 AM
I was wondering about using one input (BU0836X) for 2 encoders or switches?

For example could the Capt and co-pilot encoders for the altimeter baro be wired together and connected to one input on the io card?

I realise that if they are used at the same times, things will screw up and if the capt side is set,, it will also set the co pilots side but I can live with that.

Would there be any other issues that i could expect?

Thanks.

Ronson2k9
12-17-2010, 12:54 AM
From what I understand about encoders there is a length barrier. That is the longer the distance between the encoder and the 'receiver' (in this case the BUO836X) the greater the noise. As encoders work by detecting the change in signal the response is then transmitted to the receiver of the signal. The longer that distance the less accurate the encoder gets. It will tend to skip in it's transmission. Max distance is about 15 inches. After that noise will begin to creep in. This could be exasperated by having 2 connected in parallel as you are splitting the voltage between the 2 of them.

Shouldn't be hard to test before you install though. I don't think you would harm the BUO836X by doing that in a test rig. You could test the distance before signal loss becomes a problem and see if you can apply that your MIP configuration.

Coincidently if you connect 2 encoders to the same control the one being moved will over ride the one that is stationary. In this instance 1 of you will be setting the barametric pressure for both altimeters. As you can have more then one altimeter in the aircraft each one would be set individually - in a real aircraft. However in the flight sim there is only one altimeter even if you display 2. This would have you adjust the other one un-prototypically. This would be the case even if you need 2 cards to do the job. As you are still applying this to a single control.

Leo Bodnar
12-17-2010, 04:51 AM
Noise does not affect encoders because they are essentially two switches in a fancy enclosure. Where have these 15 inches, voltage sharing and signal degradation came from??

Spitfire9, the parallel connection will most probably not work.
Encoders are switches. They may stay in ON state even when stationary and if paralleled one encoder remaining in ON state will not allow the other one to be detected. The probability of OFF state (allowing the other to work) in CTS 288 encoder is 25% and E37 is 50%.

spitfire9
12-17-2010, 02:04 PM
Thanks much guys .
I'll wire them independently.

Leo,, if you are still watching this thread,, I read somewhere that I could order the BU0836X cards with custom names ?? Is this correct,, if so how would I go about it?

Thanks again.