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    Is it possible to drive FDU90 Ultrasonic sensor without using FMU90 Transmitter?

    Someone has gave me a FDU90 sensor (Ultrasonic sensor for non-contact continuous level measurement from Endress+Hauser which is quite famous in non-contact level and flow measurements)
    Apparently it is for connecting to FMU90 transmitter (from the same company). But I was wondering is it possible to drive FDU90 sensor without using a FMU90 transmitter?
    I mean there is no information about the pinout. The sensor has a 3-pin industrial connector. I assumed it is a common 3-wire 4-20mA sensor but apparently it's not.

    Does anyone has any information about these sensors?



    FDU90 sensor: https://portal.endress.com/wa001/dla...96FEN_1512.pdf

    FMU90 Transmitter: https://portal.endress.com/wa001/dla...90FEN_0709.pdf
    Last edited by BradtheRad; 29th December 2016 at 03:48. Reason: Image converted to Edaboard attachment

    •   Alt28th December 2016, 07:28

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    Re: Is it possible to drive FDU90 Ultrasonic sensor without using FMU90 Transmitter?

    E+H documents suggest that FDU90 is just an ultrasonic transceiver. To operate it without the FMU90 transmitter unit, you have to design your own one. Guess that's not what you want or manage to do.



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    Re: Is it possible to drive FDU90 Ultrasonic sensor without using FMU90 Transmitter?

    Quote Originally Posted by FvM View Post
    E+H documents suggest that FDU90 is just an ultrasonic transceiver. To operate it without the FMU90 transmitter unit, you have to design your own one. Guess that's not what you want or manage to do.
    Thank you.
    Yeah you guessed right. It's not what I want. Did you work with E+H products or you just took a wild guess?
    I figured maybe it's a simple 4-20mA sensor. Cause the word 4mA and 20mA have been mentioned in their documents multiple times.
    And how is it just a ultrasonic transceiver with only 3-wires and they are pretty much long wires! It sounds like a current loop sensor more than a digital unit.



    •   Alt28th December 2016, 19:28

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    Re: Is it possible to drive FDU90 Ultrasonic sensor without using FMU90 Transmitter?

    I did not use this particular E+H product.

    It's clear from the context that the 4-20 mA interface is allocated at the transmitter unit. The documentation doesn't explicitly describe the type of interface between transmitter and sensor unit. It tells that there's a sensor identification feature and an integrated temperature measurement.

    There are different ways to combine multiple signals on a shielded twisted pair, e.g. a bias T. The Ex documentation however suggests that transmitter AC and NTC DC signals are directly carried by the cable.



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    Re: Is it possible to drive FDU90 Ultrasonic sensor without using FMU90 Transmitter?

    Wow it's great that you got those from the documents so fast !
    By the way why do they call it the "transmitter" ?



    •   Alt30th December 2016, 18:22

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    Re: Is it possible to drive FDU90 Ultrasonic sensor without using FMU90 Transmitter?

    I was just playing with a FDU91 sensor and it has 3-wires one is shield and the others are red and yellow wires.

    A weird thing is that there is a very low impedance between the shield and the red wire in the sensor side. They are almost short circuited !

    After connecting either of red or shield wires to the FMU90 unit once you connect yellow wire to the FMU90 transmitter it recognizes the sensor model automatically.

    It's even more weirder that you can change the wires like connecting red wire of sensor to the yellow input of FMU90 gives the same result !

    I can't even figure out what is this signaling and protocol ?



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    Re: Is it possible to drive FDU90 Ultrasonic sensor without using FMU90 Transmitter?

    It should be relative easy to find out the connection type if you have the sensor/transmitter pair available. Guessing about it from a distance is not so effective.



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