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  • F2-04AD-1 and DoMore

    Hi all:

    I'm trying to set up 4-20mA analog inputs on a DoMore DL205. I have it working, but I'm not seeing anyway to detect that a current loop is open. 0mA reads 0, 4mA reads 1, 20mA read 4095.

    Over a scale of 0-4095 is 1 enough of a difference to declare a loop fail/open?

    The internal flags (Xbits) do not appear to go high even when I open the circuit, only if I remove power to the entire module then it indicates all channels are bad.

    Also, I have some level transmitters that take the loop to 22.6mA to indicate an internal fault, is there a way to detect this?

    Thanks in advance,

    Will

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  • #2
    That particular module was one of the first ones that we offered and does not have loop detection built in.
    If you have an urgent issue, please contact AutomationDirect's Technical Support team.

    AutomationDirect.com Technical Support: 1(800) 633-0405 or (770) 844-4200 Email Tech Support

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    • #3
      Can you recommend one that does? It's fairly important that I know if loop is <4mA or > 20mA.

      Thanks, Will

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      • #4
        You could use the F2-04AD-2 VOLTAGE input module. Place a precision 400 ohm resistor across each input. This would give you 1.6 - 8 volts for the 4 - 20 ma range. The extra below and above would give you your detection areas.

        Edit - to ControlsGuy - Sorry, I really, really, really didn't see it.
        Last edited by bcarlton; 09-17-2014, 06:11 PM.
        thePLCguy

        Bernie

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        • #5
          LOL Bernie, that's like word-for-word what I recommended on the Host version of this question!

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          • #6
            Thanks, I understand that.

            My question is since I'm stuck buying a new module anyway, is there one that provides this functionality without use of external components?

            What is the point of 4 individual status flags that all indicate the condition of the module and not the condition of each loop?

            Thanks again,

            -Will

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            • #7
              Any of the 8 channel cards support broken transmitter detection.
              If you have an urgent issue, please contact AutomationDirect's Technical Support team.

              AutomationDirect.com Technical Support: 1(800) 633-0405 or (770) 844-4200 Email Tech Support

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              • #8
                Although I don't believe any of them have sufficient overrange capability to accommodate his 22.6ma signal. It only helps with the loop break detection.

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                • #9
                  Bernie, that is not in any way (at least in my mind) something that demands an apology! I just thought it was cool in sort of a "great minds think alike" kind of way that we would come up with exactly the same idea so I commented on it. No worries!

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