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Generic wall controller

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  • 06-08-2012 7:04pm
    #1
    kkelly77
    Registered Users Posts: 1,673 ✭✭✭


    Can anyone recommend a generic wall controller, 0 - 100% gauge, that is 4-20mA?

    Looking for something to control a fresh air damper with an actuator. Only has to control damper position. Not room temp etc. Cheers.


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    #2
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    kkelly77 wrote: »
    Can anyone recommend a generic wall controller, 0 - 100% gauge, that is 4-20mA?

    Looking for something to control a fresh air damper with an actuator. Only has to control damper position. Not room temp etc. Cheers.
    You want something that can provide an analog output (4 to 20mA) signal to a damper ?

    What is the 4 to 20mA signal based on, temp, RH or a pot ?


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    #3
    kkelly77
    Registered Users Posts: 1,673 ✭✭✭kkelly77


    .


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    #4
    kkelly77
    Registered Users Posts: 1,673 ✭✭✭kkelly77


    2011 wrote: »
    You want something that can provide an analog output (4 to 20mA) signal to a damper ?

    What is the 4 to 20mA signal based on, temp, RH or a pot ?

    Yes, analog output. Signal based on pot more than likely. There'll be a PLC involved too.


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    #5
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    kkelly77 wrote: »
    As above, only has to control damper position i.e. how open/closed it is.
    If the 4 to 20mA signal is the output, what is the input?
    In other words when do you want the 4mA output, when do you want 12mA output etc?
    Is this decided by the position of a pot?


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    #6
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    kkelly77 wrote: »
    Yes, analog output. Signal based on pot more than likely. There'll be a PLC involved too.

    You could connect a pot to a 4 to 20mA transmitter like this one to an analog input to the PLC. This could be used to drive an analog output to your damper. The PLC can then be used to implement some sort of control algorithm as well as monitoring the pot position.


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    #7
    kkelly77
    Registered Users Posts: 1,673 ✭✭✭kkelly77


    2011 wrote: »
    Is this decided by the position of a pot?

    Yes.

    Ideally just want a simple controller similar to something like a dimmer switch with a 0-10 or 0-100 reference gauge on it.

    Found something along those lines on a US website that don't deliver. Just looking for something like that here.


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    #8
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    kkelly77 wrote: »
    Yes.

    Ideally just want a simple controller similar to something like a dimmer switch with a 0-10 or 0-100 reference gauge on it.

    Found something along those lines on a US website that don't deliver. Just looking for something like that here.

    I bought several transmitters suitable for a pots from Insteco (041) 988 4288 last year.


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    #9
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    Or try Radionics. Here is a transmitter for a PT100. It is only €60 and you could connect a variable resistor straight in.


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    #10
    kkelly77
    Registered Users Posts: 1,673 ✭✭✭kkelly77


    Would you know where I can get a surface wall controller like THIS but obviously not for volume control. Something that has 0 - 10 or 0 - 100 markings on it?


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    #11
    DublinDilbert
    Registered Users Posts: 5,379 ✭✭✭DublinDilbert


    Sorry it's not clear what you are asking for?

    You can't just say "a controller".

    Are you looking for a potentiometer which can supply a 4-20mA signal to a plc? It would be easier to have a potentiometer supply a 0 - 10v signal to the plc.

    You can take a €1 blanking plate and just bolt on a potentiometer. The likes of RS will sell pots and knobs.


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    #12
    kkelly77
    Registered Users Posts: 1,673 ✭✭✭kkelly77


    DublinDilbert wrote: »
    You can take a €1 blanking plate and just bolt on a potentiometer. The likes of RS will sell pots and knobs.

    That sounds like what I'm after. Just wondered if there are units available without having to do the whole make it yourself thing.


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    #13
    DublinDilbert
    Registered Users Posts: 5,379 ✭✭✭DublinDilbert


    You probably will find something out there, but most people will just make it up. Try RS.

    Also you could use a 10k pot with a 15k resistor on the top side. So with a 24v automation supply, the max you'll get will be 10v.


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    #14
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    DublinDilbert wrote: »
    It would be easier to have a potentiometer supply a 0 - 10v signal to the plc.

    Yes that would be very straightforward, but I think that most modern PLCs will not have a 0 to 10V input. I have seen this on plenty of older PLCs, but I think that all of the modern ones I have seen just use 4 to 20mA.

    EDIT: I just had a look at a few Siemens and Texas Instruments PLCs and all of the AI can be configured for voltage or current. Therefore DublinDilbert's solution is likley to work out for you. It is more normal nowadays to use 4-20 mA analog I/O. In many places (in the pharmaceutical industry in particular) it is a site standard.


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