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EL3356-00x0 | 1 Channel Input Terminal, Precise Resistor Bridge (strain gauge) · 0 次阅读

Basic function principles

Basic function principles 1:

EL3356 and special versions

Unless stated otherwise, the designation “EL3356” always refers also to special versions such as the EL3356-0010.

The measuring functions of the EL3356 can be described as follows:

  • The EL3356 Analog Input Terminal is used to acquire the supply voltage to a load cell as a reference voltage, and the differential voltage that is proportional to the force acting on the cell.
  • A full bridge must be connected. If only a quarter or half bridge is available, external auxiliary bridges should be added. In this case, the nominal characteristic value should be modified accordingly.
  • The reference and differential voltages are measured simultaneously.
  • Since the two voltages are measured at the same time, there is basically no need for a high-precision reference voltage with respect to the level.
    On changing the reference voltage, the differential voltage across the full bridge changes by the same degree. Therefore a stabilized reference voltage should be used that is subject to only low fluctuations (e.g. the EL95xx supply terminal).
  • The change of the quotient of the differential and reference voltages corresponds to the relative force acting on the load cell.
  • The quotient is converted into a weight and is output as process data.
  • The data processing is subject to the following filtering procedures:
    • the analog convertor (ADC) integrates over 76 samples
    • calculation of mean values in the averager (if activated)
    • software filter IIR/FIR (if activated)
  • The EL3356 has an automatic compensation/self-calibration function.
    • Default state: self-calibration activated, execution every 3 minutes
    • errors in the analog input stages (temperature drift, long-term drift etc.) are checked by regular automatic calibration, and compensated to bring the measurement within the permitted tolerance range.
    • the automatic function can be deactivated or activated in a controlled manner
  • The EL3356 can also be used as a 2-channel analog input terminal for voltage measurement.
    Please note: the PDO Ctrl (CoE 0x7000:0) has no function in this case.
  • The EL3356-0010 and EL3356-0090 have a timestamp function that can be activated through Distributed Clocks
    In DC mode the filter functions are inactive.
Further Information