General Input Unit - Sensor Choices

Discussion in 'C-Bus Wired Hardware' started by NickLocke, Feb 15, 2006.

  1. NickLocke

    NickLocke

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    Folks,

    Cheeky use of your brainpower here. I am looking to use a General Input Unit to handle external temperature, humidity and light sensors. The sensors I am looking at come in both 0-10v and 4-20mA variants. What decision process should I go through to make the best choice? I assume that cable length will be a factor - I am expecting a maximum of five metres.

    If anyone wants to see the sensors, they are at www.titanproducts.com - and I would welcome any advice on alternatives if anyone has experience.

    All thoughts welcome. Thanks in advance,

    Nick
     
    NickLocke, Feb 15, 2006
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  2. NickLocke

    znelbok

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    For longer runs 4-20 is the go. Foe five meters, no so much.

    Using a 4-20, you can break into the loop and add other devices such as indicators and repeaters etc.

    Personally, I would use 4-20, mainly because thats what I do at work. In the end its converted to a voltage anyway

    Mick
     
    znelbok, Feb 15, 2006
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  3. NickLocke

    NickLocke

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    Any other thoughts / opinions ?

    Thanks Mick.

    Anyone else anything to add before I get the cheque book out?

    Cheers,

    Nick
     
    NickLocke, Feb 17, 2006
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  4. NickLocke

    rhamer

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    I don't have much experience with them per se but I would second Mick's advice.

    Using 4-20ma current loop is designed to null out the efects of the cable resistance. So you don't have to be so concerned about cable type and length.

    Cheers

    Rohan
     
    rhamer, Feb 17, 2006
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  5. NickLocke

    NickLocke

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    Two more questions

    Thanks guys, 4-20mA it is then. 5504GI on order and three sensors (light, temperature and humidity) on the way too. Some more questions:

    The installation guide for the 5504 says it needs 24V ac/dc, but later on says 24v AC. I am not sure whether using 4-20mA sensors removes the need for a stabilised 24vDC supply? If not, then how can I feed the 5504 what it needs for its internal workings, whilst getting an appropriately stabilised voltage out to feed the sensors? So far as I can see, going 4-20mA means that the voltage feed to the sensors MUST come from the 5504's unregulated output.

    Secondly, I have had a look at the Toolkit screens and there is a lot to learn. Is there any documentation beyond the installation guide which might help me?

    Thanks,

    Nick
     
    NickLocke, Mar 5, 2006
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  6. NickLocke

    RatDeSewer

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    Hi Nick,

    The PCGIM can accept either 24V DC or AC as an input. This is rectified and filtered to provide a DC output voltage (labelled as 24V DC out) and regulated for internal circuits. The 24V DC output is NOT regulated, so may be as high as 1.414 * 24 or 34V. If you need to regulate it that is something you need to organise.

    You can use an external power supply to power your sensor. You may need the commons of both units to be joined - this will depend on your sensor and power supply. The 4-20mA current must flow in through the sense terminals and out of the PCGIM's common.

    I suggest you contact Clipsals Tech support for more information about setting the PCGIM up.

    Cheers

    RDS
     
    RatDeSewer, Mar 5, 2006
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