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View Full Version : senors trips/sec., anyone wanna help me?


SupermileagePLC_Newb
March 8th, 2004, 09:01 AM
I need my PLC to read 6 and 3 sensor trips every second. How would I go about doing this? Questions, concerns or confusion, post back. Thanks you.

Doug-P
March 8th, 2004, 09:09 AM
Do you mean that there are two sensors - one trips six times/sec and the other three times/sec?

What are the sensors sensing?

elevmike
March 8th, 2004, 09:44 AM
Are you working on the car? If so did you read my last post here (http://www.plctalk.net/qanda/showthread.php?postid=44602#post44602) ?

Anyway if your going to ignore my previous advise, or are working on something different, I would be happy to help you out. However you need to post more spicific information about your application.

This would include PLC type, inputs used, sensing device used, desired results etc..

If you are attempting to read the speed of yor car and are not concerned about sensing direction you will only need one input. The input will provide a pulse. You will read the number of pulses per second. With a little math this will provide you with the speed of your car. You will need to know the number of pulses per foot to do the calculation.

Thanks,

Mike

rootboy
March 9th, 2004, 03:09 AM
I would forget the PLC. Way overkill for what you want to do.

No sense in re-inventing the wheel, go to a junkyard and get the sensor and sensor gear from a wrecked car with ABS (anti-lock brakes). It's already setup for 12 volts, and should work quite well (and cheap). Connect it to a digital tach and you are home free.

BTW, I would look into large, skinny, high pressure wheels. Bicycle racing wheels for example. Mind how you turn though... (Hmmm, why not just use a bicycle speedometer from a bike shop?)

As an oldtimer wannabe, I personally would do the card-in-the-spokes trick (don't forget your Davey Crockett coonskin cap) and just listen to the pulses. But that's because I'm cheap.

As for cutting off the engine, I would humbly suggest that you could eyeball the speed and do this for yourself...

And evilmike, I mean elevmike, is right. It's better to keep the throttle in one place (arguably the futher from the floor the better), that's because most carburetors have an acceleration pump that squirts an extra shot of gas when the gas pedal is pressed.

Very wasteful.

Good luck :)


John