Host Engineering Forum

General Category => DirectSOFT => Topic started by: PlcThatWorks on September 29, 2010, 10:59:39 AM

Title: DL06 and measuring RPM
Post by: PlcThatWorks on September 29, 2010, 10:59:39 AM

I am working on an application where I need to measure RPM.  I have a mag pickup on X0 and one on X1, and on the shaft that I am measuring on I have two targets per pickup.  The RPM's can be anywhere from zero to 600RPM. So at 600RPM I see 1200 pulses per min. All this works just fine.  My issue is this:  I don't see a way to measure time between targets (pulses), since I can only measure time in 10ms increments, so I have to count targets (pulses) per second.  I would like to measure time between pulses, so I can calculate RPM on the fly, does anyone know of a way?

Thanks you.

Title: Re: DL06 and measuring RPM
Post by: b_carlton on September 29, 2010, 11:01:10 AM

Investigate the CTRIO add-on board.

Title: Re: DL06 and measuring RPM
Post by: PlcThatWorks on September 29, 2010, 04:41:25 PM

Yes I see it can do it, but was hoping to save $200.  I just don't see the DL06 being fast enough to do an edge timer.  10ms increments is not good enough.  Have lots of wishful thinking, but I don't want to pay $1000 for the PLC either.

Title: Re: DL06 and measuring RPM
Post by: b_carlton on September 29, 2010, 04:58:21 PM

Maybe a stand alone counter/rate meter

http://www.redlion.net/Products/DigitalandAnalog/Counters/CounterRate/CUB5.html (http://www.redlion.net/Products/DigitalandAnalog/Counters/CounterRate/CUB5.html)

Title: Re: DL06 and measuring RPM
Post by: brian101 on October 26, 2010, 07:39:41 PM

Look at Appendix E Example #1
http://www.automationdirect.com/static/manuals/d006userm/d006userm.html
With X0-X4, high speed inputs, the clock rate is much faster than you require. I think 7KHz Max.
f(Frequency) = 1200(times)/60(sec) = 20Hz No Problem...
Save you money and do it for free. Oh, You must have a plc with DC inputs. Good luck, it's all laid out in Appendix E.