Replacing a PLC with LabView Article

I just read the article "Replacing a Programmable Logic Controller (PLC) with LabVIEW and FieldPoint for Composting Plant Automation ". I am very concerned by the author's lack of knowledge about current PLC's. This article does not fairly compare the two platforms and is not accurate. For example, the author states that 100 msec is a typical response time for a PLC. This is absurd. Today, even low end PLCs can achieve responses time below 10 msec and high end PLCs even as low as 1 msec. It all boils down to specifying the right hardware for the application. One real danger the author does not address with building a "soft PLC" is the potential for the I/O not to fail to a safe condition if the operating system (Windows) lock
s up. This can be disastrous and unsafe for many control applications. I would suggest any reader that is seriously considering replacing a PLC in an industrial environment with a "soft PLC" watch out for this potential shortcoming. Readers can visit www.isa.org to find additional information on this issue.
I would not dispute that for a pure data acquisition application LabView can offer a superior solution. The safety conern can be mitigated if there is a "hard wired" safety system that has been properly designed. However, many times the PLC may provide safety shutdowns that depend on its true deterministic operating system and high reliability.
I hope that readers will not interpret this as a slam against LabView but as encouragement research this issue further from a different perspective.

I can see from your comments that you have a firm grasp of the PLC/vs PC concept, and agree with your comments. I have been an instrumentation developer/integrator for 36+ years, and have first hand experience with the situation(s) to which you refer. I have found the optimum solution has been a combination of PC/MMI software and PLC hardware. I have many such systems up and running in different industries, and have found this to be the best overall solution. Let the PC do what it does best(MMI display, complex calculations and decision making), and the PLC what it does best(solid deterministic control, with a non-windows operating system). I usually use an OPC server for communication between the two units, and with proper software design on both ends,
and a hardwired E-Stop system, excellent overall opertion/safety is achieved.
Your comments should serve as good stimulus for other developers.
Dave

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Message Edited by Adnan Z on 03-15-2007 10:27 AM
Adnan Zafar
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Somewhat duplicate post.
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sivaramkumar wrote:
Hi.I am using a CP-343 communications processor
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Rolf Kalbermatter
Message Edited by rolfk on 03-12-2009 09:07 AM
Rolf Kalbermatter
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a division of Test & Measurement Solutions

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Using PVCS keyword replacement with LabView

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> Has anyone tried using "fixed keyword expansion" with LabView? There
> is feature that you can use to replace text strings in a binary file
> but I've not been able to make it work for a VI.
I don't think that is going to work. PVCS has no way to know about the
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translate, an
d rebuild.
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Solved!
Go to Solution.

Hi simpra,
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Playing sound with labview

I have saved some sound clips into a matrix. Now I want to play the
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(button 1 for sound 1, button 2 for sound 2, etc). My problem is I can't
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VI that I can get ideas, or does someone want to chit-chat?
*peace*
DG
[email protected]
Sent via Deja.com http://www.deja.com/
Before you buy.

Hi Dorian,
I'm working on something similar. Have you looked at the telephone
dialer example that comes with labview (5.0 and 5.1)? That's a pretty
decent start.
Does someone have something better?
Cid
In article <87di90$dmv$[email protected]>,
Dorian Grey wrote:
>
>
> I have saved some sound clips into a matrix. Now I want to play the
> samples back (there are 10 of them) when I press the respective button
> (button 1 for sound 1, button 2 for sound 2, etc). My problem is I
can't
> get the sounds to play when I press the button. I've tried a case
> structure that would select the sound, but I also tried to let the
sound
> play (flipping a boolean). I can't get it to work. Does someone have a
> VI that I can get ideas, or does someone w
ant to chit-chat?
>
> *peace*
>
> DG
>
> [email protected]
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
>
Sent via Deja.com http://www.deja.com/
Before you buy.

Replacing a PLC with LabView Article

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