Analog Inputs of Group 1 broken? (M503)

  • Hi guys,

    I'm having some trouble with reading out analog input values of group 1 of my UniPi Neuron M503.
    Everything else like AO, DI, DO has been tested successfully.

    I tested in evok webinterface and codesys but the values of AI always stay close to zero (within the range of measurement inaccuracy).
    In codesys, the operating mode of every AI has been set and the conversion of the 2 result registers of every AI have been converted to REAL.

    I applied 24V of the power supply to analog inputs in 0-10V mode.
    The analog input of group 0 works perfectly fine showing 10V. But there is no change in value of AI of group 1.

    If measuring the voltage between 24V of power supply and AGND of group 1 there is no voltage drop.
    Shouldn't there be a voltage drop of 24V? Maybe group 1 has to be wired to +24V and GND of power supply seperately?
    I couldn't find anything about that in the documentation.

    Maybe you guys can give me some hints of what else to try to get AI of group 1 working.
    Or maybe this is a typical symptome of a broken device? But the confusing thing is that all of the AI of group 1 behave the same and just don't change their value beyond the range of measurement inaccuracy around the point of 0V.

    Thanks in advance,


  • administrators

    Hello @Martin-Freundl,
    first of all, you shouldn't apply 24V to a 0-10V input. There are 12.5V transils on the input, so you probably burned it.

    The voltage measurement happens between the AI input and the AGND. The AGND is not connected to any other GND. Thats why you didn't measured any voltage between AGND and 24V.