12V Signal to 24V Switch

Discussion in 'General Electronics Chat' started by Goerge99, Mar 18, 2008.

  1. Goerge99

    Thread Starter New Member

    Mar 18, 2008
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    Good day.

    I wonder if anybody out there can help me out.
    I have a 12 Volt signal coming from a field device into a PLC.
    The problem is, the field device is a 12 volt signal, and my PLC is a 24 volt.
    How can I get a 12 volt signal to switch a 24 volt signal?

    Is there any clever, yet easy way of doing this?

    Thanks for your Help.
     
  2. nanovate

    Distinguished Member

    May 7, 2007
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  3. Goerge99

    Thread Starter New Member

    Mar 18, 2008
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    I have tried to switch a 24 volt supply with the use of a diode, and a 9 volt battery.

    But I can seem to get it correct, nothing happens. The diode doesn't even blow...
     
  4. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Could you give us a little more detail? A schematic, a link to info on the PLC and the field device? My guess is that two transistors and three resistors, or a small MOSFET relay and two resistors would do it, but not knowing any more than I do now, I'll stop here.

    Ken
     
  5. Pich

    Active Member

    Mar 11, 2008
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    4
    Usually a PLC will have a 24V source, if speed is not an issue you could use a 12 volt relay and 24 v on the contacts or a solid state relay as mentioned earlier.
     
  6. thingmaker3

    Retired Moderator

    May 16, 2005
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    Can you share the manufacturer and model number of the PLC in question?
     
  7. Goerge99

    Thread Starter New Member

    Mar 18, 2008
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    The PLC range I'm using is a Delta PLC, the module has a sink and source function, depending on how it is wired.
    I'm trying to source on the PLC.

    There is a sketch attached.
    The diode Number: IN4007

    Treat the lamp in the sketch as a input to the PLC.

    Thanks
     
  8. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    "Delta PLC" is not enough info...do you have a model #? "Sink" and "Source" are usually output functions, not input. Though this might refer to pulling the input high or low. The manual should clear this up if we can get to it. :)

    Ken
     
  9. techroomt

    Senior Member

    May 19, 2004
    198
    1
    realize that you connect a sourcing field device to a sinking input, and a sinking field device to a sourcing input. quite a plc if an input channel can be user customized to either function. regardless, use a relay (12vdc coil and 24vdc power source) interfaced to the plc input. and as mr. pich has mentioned, you will have additional propogation delay of the relay, and some plc's (usually micro's) source a 24vdc for field device inputs, some don't.
     
  10. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    technroomt,

    I assume that the terminology is for industrial controllers. Since that is not my field, do you have a link or reference that I can persue?

    Ken
     
  11. thingmaker3

    Retired Moderator

    May 16, 2005
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    Delta has manufactured many models of PLC. Do you know which one you have? Some of them are capable of accepting 12V input.
     
  12. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
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    If you have or can acquire the manual for it you'll probably find it can handle a range of values. Some PLCs can be set for what voltage you want it to detect.
     
  13. techroomt

    Senior Member

    May 19, 2004
    198
    1
    ken, plcs.net has a decent tutorial on plc's that you may enjoy.
     
  14. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    techroomt,

    Thanks, I'll check it out. I don't know what I would do without the internet...haunt libraries like I used to do, I guess. ;)

    Ken
     
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