Expert Insights: Digital Output Modules Featuring Advanced Extended Diagnostic Functionality

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Can the output modules continue to operate normally and maintain a safe state when issues arise with the EtherCAT bus?


Have the output signals been properly set, and are the actual output loads functioning correctly? ...








Addressing these issues, Beckhoff has introduced output modules with self-diagnostic capabilities in recent years. This article recommends the EL2014, EL2819, and EL2044 modules. These digital output terminal modules connect binary 24V DC control signals from automation equipment to process-level actuators while providing electrical isolation. The status of the module's channel signals is indicated by LEDs. The integrated diagnostic functions can be evaluated in the controller and also indicated by LEDs. These diagnostic features simplify application maintenance. The power supply contacts are connected via cables, and the reference ground for the outputs is the 0V DC power supply contact. The output terminals are electrically isolated from the fieldbus terminals.





Including the following special features:

  • Ability to connect different types of loads (ohmic, inductive, lamp loads)
  • Short-circuit protection and reverse polarity protection for outputs
  • Integrated diagnostic options, including:
    • Short-circuit detection per channel
    • Wire breakage detection per channel
    • Overcurrent detection per channel
    • Over-temperature detection
    • Voltage loss and undervoltage detection

  • Integrated diagnostic options, including:
      • The output safe state function is set as follows:

      • Flowchart for Output Safe State Sequence During Bus Errors




    Overview of Beckhoff Output Modules with Diagnostic Functionality


    Diagnostics | General: Overload/Open Circuit

    EL2032

    2Channel 24V, 2A Digital Output with Integrated Diagnostic Functionality


    Output Current

    Short-Circuit Current    

    Channel Overload Diagnostic Function

    2A

    < 70A

    yes

    Channel Open-Circuit Diagnostic Function

    Device Diagnostic Function

    Output Safe State Configuration

    yes (Output Current < 1 A)

    no

    no


    EL2034

    4 Channel 24V, 2A Digital Output with Integrated Diagnostic Functionality


    Output Current

    Short-Circuit Current    

    Channel Overload Diagnostic Function

    2A

    < 70A

    yes

    Channel Open-Circuit Diagnostic Function

    Device Diagnostic Function

    Output Safe State Configuration

    yes (Output Current< 1 A)

    no

    no


     Channel Diagnostics|More Precise Thresholds: Overload

      EL2068

    8 Channel 24V, 0.5A Digital Output with Integrated Diagnostic Functionality

    Output Current

    Short-Circuit Current      

    Channel Overload Diagnostic Function

    0.5A

    < 1.5A

    yes

    Channel Open-Circuit Diagnostic Function

    Device Diagnostic Function

    Output Safe State Configuration

    no

    no

    yes


    EL2896

    6-Channel 24V, 0.5A Digital Output with Integrated Diagnostic Functionality

    Output Current

    Short-Circuit Current     

    Channel Overload Diagnostic Function

    0.5A

    < 1.5A

    yes

    Channel Open-Circuit Diagnostic Function

    Device Diagnostic Function

    Output Safe State Configuration

    no

    no

    yes


    EL2838

    8-Channel 24V, 2A Digital Output with Integrated Diagnostic Functionality

    Output Current

    Short-Circuit Current      

    Channel Overload Diagnostic Function

    2A  (∑ 10 A)

    < 12A

    yes

    Channel Open-Circuit Diagnostic Function

    Device Diagnostic Function

    Output Safe State Configuration

    no

    no

    no


    Extended Diagnostics | Extensions: Overload, Open Circuit, Device Diagnostics, Safe State 

    EL2014

    4Channel 24V, 0.5A Digital Output with Integrated Extended Diagnostic Functionality

    Output Current

    Short-Circuit Current     

    Channel Overload Diagnostic Function

    0.5A

    < 1A

    yes

    Channel Open-Circuit Diagnostic Function

    Device Diagnostic Function

    Output Safe State Configuration

    yes 

    Output Current < 0.2 mA

    Over-Temperature,

    Undervoltage: <17 V,

    Voltage Loss: <14 V

    yes


    EL2819

    16-Channel 24V, 0.5A Digital Output with Integrated Extended Diagnostic Functionality

    Output Current

    Short-Circuit Current     

    Channel Overload Diagnostic Function

    0.5A

    < 1A

    yes

    Channel Open-Circuit Diagnostic Function

    Device Diagnostic Function

    Output Safe State Configuration

    yes 

    Output Current < 0.2 mA)

    Over-Temperature,

    Undervoltage: <17 V,

    Voltage Loss: <14 V

    yes


    EL2044

    4-Channel 24V, 2A Digital Output with Integrated Extended Diagnostic Functionality

    Output Current

    Short-Circuit Current     

    Channel Overload Diagnostic Function

    2A

    < 4A

    yes

    Channel Open-Circuit Diagnostic Function

    Device Diagnostic Function

    Output Safe State Configuration

    yes

    Output Current < 0.8 mA

    Over-Temperature,

    Undervoltage: <17 V,

    Voltage Loss: <14 V

    yes

    This article recommends digital output modules with extended diagnostic functions, including EL2014, EL2819, and EL2044. If you have any questions, please leave a comment in the discussion section.