Data Acquisition Card or PLC

[Gerry M]

Phil,

I've made this same type of air tester before. As whether to use DAQ or PLC, it just depends what you want or need.

If you want something cheap and simple to act as a quick QC part check. Then the PLC will work fine. I usually use the AD brand stuff. Probably an 06 or 260 would work fine.

If you want to collect data at reasonable intervals, and have some sort of results display. Either method works fine.

If you want to collect data at very short intervals, collect data, and then make a comprehensive results graph, or something really nice . Then you may need the DAQ, with a PC.


Since you said your setup consists of this

I will have approximately 13 pressure transducers (analog), 2 temperature sensors, and a couple of solenoid valves.

It sounds like this is a more comprehensive design and therefore the PC will probably work best. Present your boss with a few of these solutions and see which way he wants to go.

 

[R-Phil]

Thanks Gerry and Ayman
I will present my boss with these options. Like I said I don't know exatly what he wants to see. Here we change our mind all the time so things don't usually end how they started.

If you want something cheap and simple to act as a quick QC part check. Then the PLC will work fine. I usually use the AD brand stuff. Probably an 06 or 260 would work fine.

I thought the DAQ would have been cheaper.

 

[R-Phil]

This test consists of:
- fill the component with air to the test pressure (time or pressure controlled)
- let the pressurised air dwell for a period for stability
- monitor component to detect any pressure change resulting to leaks

Any suggestions on DAQ vs PLC
Trying to get as much inputs as I can
Thanks

 

[Gerry M]

Phil,

Your sequence looks good.

You can also take a look at this Fastest

Your app. sounds a little different, but I thought I would throw it out there.

As far as cost goes between DAQ and PLC. I think it may be close, since you have so many sensors. You'ld have to add it up and compare.

Good Luck with the Boss-man!!!

 

[ragavi]

dear friends
can anybody help me in understanding step7 programming loop instruction.explain with a example
by
raji

 

[ayman metwally]

dear friends
can anybody help me in understanding step7 programming loop instruction.explain with a example
by
raji

"Alsalam alikom" raji,

I don't know any thing about S7 PLCs but there are a lot of people here can help you.

You better post this question in a separate thread, You will sure get more answers and help by S7 guys.

If you are new to forums, here is the way that you can post a new topic:



Yours, Ayman

 

[CaseyK]

A lot is personal preference. I don't like to use PC's, but sometimes PLC's aren't the best solution.

One of the worst I have seen was two OPTO 22 controls, with an ungogly amount of input modules.

Seond worst was SteepleChase PC software.

My choice up to THIS point would be a Fanuc 9030, with the LAN capable CPU module.

I had never paid attention to entertron's logger before. I am VERY impressed with what I saw on the link posted earlier. I would consider them in this application.

I have yet to run across an uphappy entertron customer.

regards.....casey

 

[R-Phil]

I had never paid attention to entertron's logger before. I am VERY impressed with what I saw on the link posted earlier. I would consider them in this application

Don't you ned a PLC in order to use the logger?

 

[Stephen Luft]

Phil,

In answer to your question, yes, you would still require a PLC or some other device that will generate the information.

The Logger is simply a device that can store information. The PLC controls how and when it sends information to be stored.

 

[R-Phil]

Thanks Stephen
Well I think that we are going with the PLC and not the DAQ.
So now I need more advices. I am thinking about going with the ML 1200. What do I need to consider?
Or any suggestions?

 

[Stephen Luft]

Phil,

The logger has not been tested with a Micro Logix, so I am not certain if the protocol will work. We require 8, N, 1, 9600 Baud from the PLC.

What we would probably need to know, is number and type of I/O you will require for this application. You gave some general information in previous posts. Now that you have decided on the type of system you will be going with, what your I/O is going to be, will most certainly determine the type / family of PLC that will meet your requirements.

Regarding the logger, how much information are you requiring to store and how often will you have access to obtaining the data?

Hope this helps.

God Bless,

 

[R-Phil]

As I understand choosing 24vdc or 120vac for my controller depends on my I/O. So can I combine some 24vdc I/O and 120vac I/O or it needs to be strict 120vac or 24vdc?

 

[Stephen Luft]

Phil,

With regards to choosing I/O...

Fixed I/O units (bricks) are specific. One or the other.

Modular Units give you more flexibility in that you can mix I/O by the modules you select.

With Entertron, for the most part, you can mix with the Elite-2000. Depending on the number of I/O, we can either mix by different boards or if your I/O is 16/16 or less, we can configure a specific board with I/O in groups of four. www.entertron.com/elite.htm Keep in mind that this controller is solid state outputs, not relay outputs.

The ML 1200 offers a set of fixed I/O in their primary block. However, you can add additional modules with various I/O configurations.

Hope this helps.

 

[danw]

You haven't mentioned any thing about the nature of the devices you're testing or to what level you're leak testing, so this note fits the category of 'unsolicited advice', but having run into this situation, I thought you might take someone else's experience under advisement.

You might want to be aware that temperature affects the pressure of a closed system, which is the physics of the Ideal gas law.

If you are testing a large volume device at high pressure, distinguishing between pressure changes due to leakage; or pressure changes due to temperature changes can be very problematic.

I found that pressure testing was a useable technique for identifying "catastophic" leaks because of the fairly rapid pressure decay from grossly bad welds or loose pipe fittings, but the effect of temperature changes on the factory floor disguised the affect of minute leaks, which required a helium leak detection system.

You might find that you need a stabilization period in order to allow your compressed gas, which transfers heat during the filling operation, to temperature stabilize with whatever it is you're testing.

Dan

 

[R-Phil]

You might want to be aware that temperature affects the pressure of a closed system, which is the physics of the Ideal gas law

I forgot to mention that 2 temperature sensors were also included in my system. So far this I need:
- 13 pressure transducers
- 2 temperature sensors
- 2 solenoid valves
- pushbuttons and lights
This is to test water jackets on cylinder heads