Data Acquisition Card or PLC

[Kevin Hammond]

If you come to a PLC site to ask "PC or PLC?", the answer you will get 99% of the time will be PLC. And in most cases, that is the best answer. I'm not sure that is the case here.

As a devil's advocate, I will tell you that with Labview you could have a working system in a couple of hours. Okay, maybe a couple of days, since you've never used Labview; but still much faster than programming a PLC and an HMI. Labview comes with canned "vi's" (virtual instruments) to do just about anything imaginable. The programming is very intuitive, and their tech support is second to none. Plus, you could probably go to their website forum and find someone who has already done your exact application or something very similar.

This just sounds like a textbook Labview application to me.

Good Luck

Kevin

 

[R-Phil]

What other components should I consider for my system. I know I will need relays for my solenoid valves, what else?
Bare with me as I mentioned before I am a beginner and this is the first time that I am putting a PLC system together.
Thanks a lot

Kevin I just saw your reply and appreciate it. I thought about that too but I guess it's up to the boss man.

 

[CLP]

If you need high resolution ( 16 bit or more) , High Sampling rate and Gain (If you are using thermocuples output will be in millivots) go for PC based measurement. Moreover Labview is very easy to learn.All the Data Acquisition programs (VIs) are already made for you.You just have to assemble those in a new VI.you will find a lot of examples in Labview. The technical support of National Instruments is very good.

In labview there are lot of programs for detailed analysis of the acquired data (like fourier transforms, curve fitting...etc ) you can also include a lot of fancy stuff in your program,(like graphs, charts etc)

The labview software you can use for future applications also.It is very useful language to get things done quickly.

PLC are good at ON/OFF controls which involve 100s of I/Os.

I am just a beginner in PLCs with few months experience in LV.So please correct me , if I am wrong

Best Regards,
Abhi

 

[Gerry M]

Phil,

I think everyone has given or hinted at most of what you need.

I think you just need to understand the application fully. Find out what it's requirements are, such as how much pressure, allowable pressure drops, in what amount of time, what accuracies are required, why an air test how about water. That sort of stuff.

Then find out why there are two temp. sensors and thirteen pressure sensors. Why not just one of each. Whoever came up with your current setup must know alot of details about the test that need to be considered.

Then the requirements for your analog inputs, etc. can be derived from that. As well as whether it should be a PC or PLC. In other words you need the equipment that matches the application requirements. Sometimes the smallest details, like accuracy and sample time, can determine what equipment you buy for your control system.

 

[R-Phil]

Thanks guys
I appreciate those replies. These past couple days I have been reading documentations on DAQ cause my boss gave me his old DAQ components. Man, there are a lot of old cards and modules that ni don't even manufacture anymore. The labview version is 4.1. But I am starting to understand the requirements for a DAQ system. I talked to an ni representative and he told me that my components were too old and is sending me a quote for what I will need for my system.
Well I guess I will have to check with the boss man.
However I'll have more questions when I know more about my setup

 

[ayman metwally]

Another thing (say things) you must consider when are using LabVIEW:

The base package of LabVIEW 7 Express doesn't include the following:

1- The abiltity of building packages (setup.exe and these kind of stuff)

2- The ability of generating MSword or MSExcel reports.(but they have other options, which I don't like)

So, They sell a plug-in module for building packages, The call it (Application Builder)
And the aslo sell another plug-in module to generate Word & Excel reports, They call it (MS office report generation toolkit)

Of course, I hate NI for doing that !

But you have to take care of these couple of things if you are willing to use LabVIEW, there are extra $$$ !!