Application Example - RPM Measurement by Proximity Sensor

Hi, 

I am looking for an application example for RPM measurement done by a proximity switch!

Cheers

Hello,

as I see you as experienced user, only (hope it can be also helpful to you) this standard document is good, also with some know-how. As there are some clear infos (hope I was good understand that), via simple pulse catch it can be probably solved.

http://www.opto22.com/documents/1784_rpm_measurement_techniques_technical_note.pdf

MicroMan

Hi, 

I am looking for an application example for RPM measurement done by a proximity switch!

Cheers

To further the conversation...
I have not searched for such application example -
but some detail would be instrumental in what will work.

Which PLC and extension cards do you have for this project?
Or are you able to specify them still?

In what range (kHz) do you think the sensor would pulse at?
How accurate do you need?

External devices can do this job and give a value per communication or analog feedback. If you want something a little more accurate and the PLC is not "strong" enough, then this is a good option.

I prefer using an S7-200 or S7-1200 even more than CPU31xC as to avoid needing special cards to read the input quickly enough.

Cheers.

Piotr.M

if you are using the sensor input without a counter card: use TON timer:

I used it for S7-300 project and it worked well [it does measure spool revolution time which is 5+seconds)

I would go for hardware interrupt.. if available.
Then capture the PLC system time at each interrupt.

Trouble is... hardware interrupts are not always available.

Hi,

Thank you for your responses. I was after an application example issued by Siemens.

To cut it short: I am working on a validated system. I needed to close a deviation: code have a control module for DI, the Scada have requirement for display in RPM. My validation people offered me this easy way out, that why I was desperate to have a "valid" source.

Thank you anyways!

Piotr.M

Hi

What do You mean by validated example?

The Siemens examples do came with condition 'use at your own risk' i.e.

Siemens is not responsible for any bugs in their examples and final engineering
of the solution is the developers' responsibility.

[CONVERSATION]
A valid argument you are making.

But I think the real point is to have some mechanism that can be verify the work already done. The idea is to get something from a 3rd party and not from the original designer of the 'thing' that needs verification.

If code from Siemens (or other independent 3rd party) gives the same result.. then the verification is made.

(naughty smile) Maybe get Omron rep to demonstrate their RPM counter device at the clients' plant <hint hint>.

w

Yes, that is also a good point. Anyways my validation folks accept it, and I  am trying to make them happy. 

Of course there is a Test Procedure on place to verify the functionality. 

I'm also looking for that. Can you share the application example for that? 

Thanks in advance.