Created Date: February 21,2015

Created by: milldrone

The shaft will turn 400 - 700 RPM. The sprocket is 18 tooth.

In your first post you mentioned that you had an "inductive speed sensor ", any details on this?

I'm presuming because you also mentioned an AC signal that you have a DL05 with AC inputs.

Does your shaft instantly reverse? Or does it slow down stop then accelerate to your 400 to 700 RPM?

If your shaft does slow down and accelerate slow enough then a pair of AC proxes set at 90 degrees (shaft rotation) from each other might work if you can afford to have a sensing target that is 1/2 of the rotation of the shaft. I'm fairly confident that a 18 tooth sprocket would be too fast without a high speed counter.

Created Date: February 22,2015

Created by: bcochran79

I have a passive 2 wire inductive sensor that creates an AC sine wave with a frequency corresponding to the passing of a target in front of the sensor. The problem is that I am using a PLC with discrete digital I/O, no analog inputs. I would like to interface the sensor to the PLC, and write a program so that the PLC can simply determine if the shaft is turning. I do not need to determine direction or anything like that.

Created Date: February 22,2015

Created by: Tinker

I am interested in using a DL-05 PLC to detect the rotation of shaft and open/close contacts accordingly. The shaft is currently fitted with a sprocket monitored by an inductive speed sensor that creates an AC voltage output as the sprocket turns. I need a circuit to interface this AC sensor with a discrete I/O input(s) on the plc. I think I need to turn the sine wave into a square wave, but there may be other methods, I am not sure. Any suggestions?

Sounds like you have a Variable reluctance sensor , you will either need to "turn the sine wave into a square wave " (see link), or perhaps easier, add a solid state proximity sensor. 700rpm * 18 teeth / (60 seconds per minute) is only 210Hz, probably not too much of a problem. While you did mention AC regarding the sensor, I'm assuming that you have a DC input '05, an '05 can count at up to 5kHz, so I don't see any problem there.

Do you just need to know if the shaft is turning, or do you need to know the direction? if the latter, you will need two sensors located n+1/2 a tooth apart (where n is any integer, space may prevent literally 1/2 tooth separation, but 1-1/2, 5-1/2 whatever, works the same), if you are adding at least one new sensor I'd add two and not bother with converting the existing sensor to pulse. Actually even if you do not need 2 sensors, I think that adding a new sensor will be easier that getting a signal conditioning circuit for the existing sensor.

Created Date: February 23,2015

Created by: Cap

I had a need to use a VR sensor on a PLC Application.. It's a PITA..

I'm a pack rat, so I still had some old 405 PLC stuff, and I purchased a VR input card from AD to fit the 405 system.. a little cumbersome to program the mag input card.. but it works..

In my hunting to NOT have to use the 405 system, I found a VR amp that was SMT mount.. that could be placed on a SMT to DIP adaptor, then wire up from there.. again a PITA.. and I really did not want to breadboard something for this.. so I went the 405 route..

you might be better of, replacing the pick up coil with a prox sensor..

if you find anything better for waveshapping the VR output.. please share..

Cap

Created Date: February 24,2015

Created by: ljbeng

If you have an AC signal and DC input PLC, it seems you just need a diode in series to knock off the negative side of the sine wave. As long as the positive side reaches an rms greater than the dc input detection voltage and the frequency does not rise above the speed of the high speed input, you should be able to detect those rising and falling pulses and just latch up the output you need. Use a timer to detect the pulses have stopped for an unlatch.

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