PLC vs Data Logger

LEILAGFONSECA · Feb 29, 2008

Hello Guys,

ok...that is my problem: I have an application that is quite simple with few I/Os, but it requires 500 kHz.
I don't know if I use a PLC or a data logger. I'll also need some vibration measurements that I saw that a data logger from Delphin have.
But (please correct me if I'm wrong) as far as I know data loggers are devices just to data acquisition and not to do any control and PLCs, if you know how to program it, the control features are almost unlimitted.
I'll need (talking about PLC) a distributed I/O. So I'll install many remote I/O and connect them to a CPU. If I use data loggers what would be the architeture? The data loggers have their data storage on them? How does it work? I quite understand about PLC but not about data loggers. Are they faster then PLCs? I mean to achieve the 500 kHz...

I would like you to help how to choose the best option...

Thanks!

JesperMP · Feb 29, 2008

Dont know much about dedicated highspeed datalogging.

But I know that you cannot use a PLC to log something that changes at 500 kHz.
There are highspeed counters for PLCs but that is not what you are after.

cntrlfrk · Feb 29, 2008

I can't imagine what on earth you would need to measure and log at 500kHZ, except morse code.

http://en.wikipedia.org/wiki/500_kHz

Peter Nachtwey · Feb 29, 2008

You need to rethink this. You can't be serious.

LEILAGFONSECA said:
Hello Guys,

ok...that is my problem: I have an application that is quite simple with few I/Os, but it requires 500 kHz.

That how much data every 2 microseconds? At that rate you will quickly use all the PLCs or data logger's memory. This requires special hardware that can read the data and put it into memory WHITHOUT using software. This is called direct memeory access. At this rate the ability to do any control would be serverly limited because all the memory bandwidth will be use storing data.

I doubt the I/O can even respond that fast.

danw · Feb 29, 2008

Your application falls into the 'Test and Measurement' field, not industrial control.

'Ordinary' data loggers log at second, minute or 0.10 second intervals, not 0.000002S intervals.

The former Hewlett Packard, now Agilent, dealt in with past with high speed data acquistion, I suspect Agilent does as well.

20 years ago, there were dozens of small companies that offered various solutions as well, but I haven't played there in 20 years so I can't help with specifics.

Dan

LEILAGFONSECA · Mar 4, 2008

Thanks guys!

LEILAGFONSECA · Mar 4, 2008

Ok! Now I got the things clear. Dan was right, this application is not control application but just data acquisition. He knows that this value is quite high but that's what he supposes in a first step.

So I'll give a look in high speed data acquisition hardwares.
If you know anything else please tell me.

Tks!
Leila

roadwarrior · Mar 4, 2008

Check This Out

http://www.redlion.net/Products/ProcessControl/ModularController/ModularControllerMaster/CSMSTRLESXGT.html

I have used these quite a bit, and have had very good luck with them. And they will talk any protocol to any processor and store the information in an Excel spreadsheet that is accessible over ethernet. Think this might be the ticket for you.

Let me know what you think

Mickey · Mar 4, 2008

See link
http://www.ni.com/dataacquisition/

jeff s · Mar 5, 2008

I use a logger from dent instruments.good for readings down to every three seconds.

http://www.dentinstruments.com/

leitmotif · Mar 5, 2008

Check with John Fluke

Dan Bentler

kdcui · Mar 5, 2008

Does National Instruments have anything that works at that speed? I know they have some specialized data acqusition equipment (DAQ).

Unfortunately I think most of it is expensive, and uses the proprietary LabView software...

danw · Mar 5, 2008

kdcui said:
Does National Instruments have anything that works at that speed? I know they have some specialized data acqusition equipment (DAQ). Unfortunately I think most of it is expensive, and uses the proprietary LabView software...

Handling data at those rates 20 years ago was DMA work or buffer & dump, either were proprietary.

Memory is a trivial fraction of the cost 20 years ago, but even so the DAQ rate is high for long periods, unless it's snapshot application that an ordinary (digital) oscilloscope would handle.

Features like antialiasing and amp slew rates become important at those DAQ rates.

Dan

LEILAGFONSECA · Mar 6, 2008

DENT doesn't have any hardware for that specification, but I found something with Dspace and NI.

Road Warrior, It's being really hard to contact Redlion...

Anyway, I'm already finding some solutions..
For sure after I find it I'm gonna be here again to ask more questions

Thanks guys!!!!

DanYost · Mar 6, 2008

How did you try to contact us? You can contact us through this forum, or via [email protected].

We also have a good distributor in Germany: http://www.wachendorff.de/

Regards,
Dan

PLC vs Data Logger

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