Basic function principles

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.