Pressure transducer

Discussion in 'General Electronics Chat' started by yassser, Jan 7, 2014.

  1. yassser

    Thread Starter Member

    Jul 25, 2011

    I have a question about a pressure transducer , its output is in the form of a current signal varying between 4 and 20 milliamps , with the following wiring diagram.


    the module has only two wires coming out of it , connected as descriped in this firure , I wonder how there is no ground wire to the module , and what would this ground sign circled in blue be connected to .

    or does the module act like a varying resistance that changes as the pressure changes , hence changing current ? but the datasheet says that the direction of the wires cant be reversed , so it cant be simply a resistance.

    this is the datasheet link
  2. MrChips


    Oct 2, 2009
    This is a 4-20mA current loop module.

    It is an electronic device that controls the current through the device. It uses a transistor to regulate the current and hence it is sensitive to voltage polarity, i.e. you cannot reverse the connections.

    It does not require a ground connection.
    yassser likes this.
  3. wayneh


    Sep 9, 2010
    That's one way to think about it. It's self powered by the voltage across its inputs. The few I've dealt with were not able to operate in reverse - they were polarity dependent. I suppose one could be designed to self-adjust.
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