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  1. #1
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    Trane MP-503 Input question

    On a Trane MP-503 input set for binary - what is considered "open" and what is considered "closed" contacts?

    I'm in the office reveiwing drawings and the drawings say that zero volts is shown as "open contacts" and 24v is shown as "closed contacts". That is backwards from what I would expect.
    If "I have always done it this way" is a good reason to do it again, how many times do I have to do something wrong - before it becomes right?

  2. #2
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    Dec 2007
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    I would think that the device puts out a 24v out looking for status. If it reads 0v the contacts are open breaking the circuit, if it reads 24v the contacts are closed completing the circuit.

  3. #3
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    Jan 2008
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    The bop's are 24v output. This means when the output is on, your energizing the end device with 24 volts ac. The binary inputs on the other hand feed out a 5vdc that it will need to see loop back in order for it to recognize the binary input as "closed".

  4. #4
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    Dec 2007
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    Quote Originally Posted by BAS_Tech View Post
    The bop's are 24v output. This means when the output is on, your energizing the end device with 24 volts ac. The binary inputs on the other hand feed out a 5vdc that it will need to see loop back in order for it to recognize the binary input as "closed".
    He is correct, Do not put 24 volts on the INPUT or you will have a bad input.
    The BO is 24 VAC to make a relay, The input needs to be a dry contact as the signal is 5v like BAS Tech said.

  5. #5
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    Jan 2008
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    Of course I'm correct. I work for the manufacturer.

  6. #6
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    Quote Originally Posted by BAS_Tech View Post
    Of course I'm correct. I work for the manufacturer.
    What Location?

  7. #7
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    Jan 2008
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    Chicago/West Michigan.

  8. #8
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    Dec 2007
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    Quote Originally Posted by BAS_Tech View Post
    Chicago/West Michigan.
    Greensboro NC

  9. #9
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    Quote Originally Posted by BAS_Tech View Post
    The bop's are 24v output. This means when the output is on, your energizing the end device with 24 volts ac. The binary inputs on the other hand feed out a 5vdc that it will need to see loop back in order for it to recognize the binary input as "closed".
    This is more what I would expect. I would also expect that when I measure 5volts across the input, the MP-503 will consider the contacts being monitored to be open. And when the contacts are closed, I will measure zero volts across that input.
    If "I have always done it this way" is a good reason to do it again, how many times do I have to do something wrong - before it becomes right?

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