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Control & acquisition system

Control & acquisition system

Control & acquisition system

Hallo to everybody !
Please, I am dealing with following situation:
I have to choose between a system where acquisition system is realized by one brand, while control system is realized by a second one.
The second possibility is to choose a single system, where acquisition & control are realized by a sole brand.
What I have to regulate are valves, electrical motors – by an inverter – and I have to measure temperatures and pressures.
The inlets/outlets are 4-20mA modules , or 0-10V or 24V
Please, has anybody any experience with the case above ?

Can anybody of you suggest me some brands, should it be the case I would contact them ?

Thanks in advance !

RE: Control & acquisition system

I cannot give you brand names as your question is hideously vague.

All these signal types are standards so you can mix and match brands all you want.

However, the mere fact that you've asked this question leads me to think you may want a specialist or a vendor to do this or stick,(if you can), with one brand.

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Control & acquisition system

Many Thanks Mr. Cress,
indeed my question is general, but my intention was not to make it hideous!
Are there any details that could give you more issues to answer me in a more precise way ?
As a matter of fact I'd like to know only in anybody has dealt with this kind of situation, and if making a choice determined  a mistake or not!
To share some experience is one of the reasons of the utility of forums, in my opinion!

RE: Control & acquisition system

Hi MrReds.

It really depends on more details.  What kinds of things are you controlling?  What kind of sensors are you using?  What type of process is it?

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Control & acquisition system

Hallo Mr. Keith !
> What kinds of things are you controlling?
> What kind of sensors are you using?
I am controlling valves to regulate and mix water flow, and two inverters, to regulate electrical motors.
What I am measuring are temperatures with thermocouples and pressures with pressure sensors.
> What type of process is it?
I am dealing with the climatization of a building

Thanks !

RE: Control & acquisition system

You could use "off the shelf" HVAC systems.  Honeywell comes to mind as does Siemans.  If you want to do more work and customize the PLC, then they both will do it.  PLC direct, AB, GE all make small PLC's with modest HMI's.

RE: Control & acquisition system

Look at Mitsubishi-Programmable Logic Controllers and Variable Frequency Drives.


Function Blocks are availabe for almost any type of I/O you will need.

RE: Control & acquisition system

Some drives have a basic PLC built in and network capability. They're available from a number of manufacturers, e.g. the Unidrive from Control techniques among several others. There are some good and bad aspects to putting all the control in the drive, most of which depend on how complex the application is.

If we learn from our mistakes I'm getting a great education!

RE: Control & acquisition system

Perhaps one of these will do
Look at the RMC151E
This is a motion controller ( hydraulic and electric motor ) that has 64MB of ram on board and it can control up to 8 axes.  Any axes not used can be used for other I/O.  The controller can log 16 items at a time a rates up to 0.5 milliseconds and the is a big buffer so the data collection system has plenty of time to read out the data over the internet.   The controller is also programmable.  The programs run synchronously with the closed loop control.  This makes the response very deterministic.  Note, this could be overkill because of the speed.  The controller is used a lot in testing systems where control and data acquisition is key.

RE: Control & acquisition system


Nice!  They look pretty pricey though.
Not compared to some of the big manufacturers controllers and they don't have the memory and the data acquisition features.  These features may reduce risk and simplify integration until MrReds finds the the perfect solution.  I admitted it may be overkill.

RE: Control & acquisition system

As a teacher of hvac electronics  (Direct Digital Controls)
 I like Computrols because they are very easy and comprenensive If you are interested go here and check it out: http://www.computrols.com/

RE: Control & acquisition system

Hallo and thanks to everybody.
First of all please let me send to all of you my best wishes for a wonderful and successful 2008.

After receiving your great suggestion, I've been offered by following systems:
Yokogawa/Eurotherm/Agilent/Siemens/National Instruments/

Does anybody of you have got any experience or suggest me any web page where there is an evaluation on this systems ?

Thanks in advance !

RE: Control & acquisition system

Agilent and NI, and possibly Yokogawa depending on which part of the company you are talking to, are primarily manufacturers of measurement & test equipment and their equipment is designed for that type of environment where it will be used by trained and competent people.

Eurotherm, Siemens, and possibly Yokogawa are primarily in the industrial controls filed and their equipment is designed for that environment.

Of the options you have presented and the almost total lack of information about your application I would probably go with Siemens because of the versatility of their PLC range and the amount of third party support available from the system integrators. There many other PLC brands out there, some of which are comparable with the Siemens range in cost and capability and others which are cheaper and less capable.

You should also have a look at the specific hardware for building management from, for example, Landis & Staefa or Trend Controls which might be a better match to whatever you are trying to do. L&S appear to have been absorbed into Siemens since I last had any contact with them.



You need to define your problem much more clearly in the form of a specification because at present people are wasting their time speculating about possible solutions to your problem which you haven't yet defined in any detail.

If we learn from our mistakes I'm getting a great education!

RE: Control & acquisition system

Good Morning Mr. Scotty,
and thanks for your answer.
concerning your
>You need to define your problem much more clearly in the form of a specification

please not that it was not my intention to make waste time to people.

Nevertheless, please, do not hesitate to ask me some elements that would be useful for you to define your analysis in a better way.

AS a specified in some previous post, the final aim is to control temperature and relative humidity in a building.
The control has to be realized by:
- varying air velocity (regulating an inverter)
- regulating water flows (opening and closing valves)
The adquisition of the data is realized by temperature& pressure sensors

thanks in advance

RE: Control & acquisition system

I would definitely speak to one of the building automation companies such as the two I linked to above, or their equivalent in your part of the world. This sort of things is their everyday work.

You might get a better response if you post this question in forum403: HVAC/R engineering, but if you do transfer this discussion to a new thread please put a note this one asking people to post to the new thread. Put as much information as you can up front in the thread.

If we learn from our mistakes I'm getting a great education!

RE: Control & acquisition system

Mr Scotty,

thank you very much for your help.
Please,just one more precisation.
The initial question was: do you see - according to your knowledge and experience - any problem if using for control a system by one company and for acquisition a system of a different one ?

Thanks in advance

RE: Control & acquisition system

There are benefits to both approaches and both are widely used. You really need to decide what functions you need from the data acquisition system. If you require really good trending capability and the ability to store the huge amounts of data generated by short sample times and tight deadbands then a stand-alone DAQ might be best. If your needs are more basic then it is likely that the package available from the control system integrator will be adequate. Also do you need the DAQ to provide independent supervision of the controller using independent instruments? That would force you to go for a stand-alone system.

If we learn from our mistakes I'm getting a great education!

RE: Control & acquisition system

In a refinery or plant environment, the control system and the data aqusition system are usually be the same vendor as seamless integration, consistency and a single number to call in case of issues, etc all play a big factor.

In smaller facilities, in the field, the split is more 50-50 as availability, costs, operator familiarity, etc all play a big factor.

Good integrated systems vendors I have used include:
- Emerson (Delta V)
- Honeywell
- Foxboro

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
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RE: Control & acquisition system

Might as well add Emerson (Ovation) to that list - formerly Westinghouse Process Control. All are blimmin' expensive ways of dealing with a building automation problem.

If we learn from our mistakes I'm getting a great education!

RE: Control & acquisition system

You do NOT want to attempt to implement a complex (yet very powerful) factory DCS system (as described above) to a relatively simplistic application such as building HVAC automation, it is SERIOUS overkill.

Stick to the Building Automation people you previously described. As to one vendor or separate, keep this scenario in mind:

You have a building in which the occupants call to say they "feel" as though the humidity is high, yet your data acquisition says otherwise. You take manual site measurements and discover that it is indeed high, so something is not working correctly. But the control system is taking it's measurements from the data acquisition system for control setpoints. So, the is it because the control system is not working right, or is the data acquisition wrong? Who are you going to call? Or rather, who are you going to call FIRST?

However, if there is no interaction between the two, i.e. a redundant measurement system, then it probably doesn't matter at all.

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