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Baffled by Honeywell proximity sensor

I've been given a sample Honeywell capacitative proximity sensor by a client. He wants me to build a small micro-based project to interface with it. The sensor is shipped in a bag labeled "992AA12AN-A2", and the documentation for "992 series" sensors consists of four letter-sized sides, most of which are multilingual translations of warnings and mechanical specs. The electrical documentation supplied with this sensor is a quarter-page and not very meaningful to me. I've photographed it at

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- sorry for the nasty photo, my scanner is being recalcitrant.

The device has a blue wire, a brown wire and a black wire. Looking at those diagrams - I presume they relate to different versions of the sensor - I assume that the blue wire is supposed to be +ve, the brown is -ve, and the black is output. But when I connect a 10VDC supply and a scope, all I see on the output is 60Hz hum. I added a 500 ohm resistor between the "output" line and ground, and still all I get is hum. The device also doesn't seem to be drawing any appreciable current.

The only info I can find on the web is a bunch of people offering to sell me the datasheet, and one company saying that they have stopped selling it and now sell someone else's sensor. Does anyone know how these devices are supposed to work?

Reply to
larwe
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Not your device, but maybe this will help?

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-- ...The Bit Eimer NAR 84054 L0 "My goal in life is to be the kind of person my cat thinks he is" [remove keinewurst and reverse letters in domain to email me]

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Reply to
bit eimer

normally, the Blue is the common, brown is the Vcc and black is the load. this depends on what kind you have. you have the difference of PNP and NPN which indicate in which manner it works, either it it pulls towards - side of the + side.

in any case the BLACK wire will switch the path as you need in the doc.

Reply to
Jamie

From what I can tell, you have a NPN Capacitive Prox switch that roughly works like this.

Brown - Connect to DC positive 9 - 30 Volts Blue - Connect to DC Common, in most cases this should be machine ground Black - When not triggered, will have the same potential as Brown - When triggered, will have the same potential as Blue

The switch can handle upto 200 milliamps if it's the 12mm version through the black wire. It will incur a voltage drop of 1.75 volts if you pull the maximum load across the black wire. The switch consumes

15 milliamps by itself at most in addition to your load. Your load must be greater than 50 microamps to guarantee the switch will turn off the output.

There is also a line concearning the maximum switching frequency that you did not show. Usually for DC it's a few hundred hertz for this type. I have seen as high as 50 kilohertz in some special inductive units.

Reply to
Christopher Worley

Hi,

Thanks for the reply.. the switch frequency is not shown in that datasheet. And I'm just about to run out the door, but I quickly tried the wiring configuration you suggested and I still get exactly the same results. I'd say the sensor must be bad, but I cut open the factory packaging myself so it seems _fairly_ unlikely. Very bizarre.

Also, how did you decide that it was NPN? The "wiring diagram" has me puzzled. I can't work out if it is showing the pinouts for four different variants of the sensor, or if the left side is supposed to show what you're connecting it to in whatever the intended application might be.

Reply to
larwe

larwe...

Supply connection looks OK. Low power (milliamp or so) is normal.

The output is open collector, either NPN (with emitter at -Ve) or PNP (with emitter at +Ve). You need to connect a 1 kOhm load resistor or the inactive output will be floating, hence the 60 Hz hum (50 Hz in Europe...). With the load resistor connected to a supply rail, activate the sensor (hold your hand or a piece of metal on the face of it) and check if the output switches. If not, connnect resistor to other supply rail and try again.

Regards, Arie de Muynck

Reply to
Arie de Muynck

look at the part number. normally the last Digit or charactor. let N or P

Reply to
Jamie

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