IEPE high pass properties

For optional regulation of the IEPE bias voltage, the ELM360x has an adjustable 1 st order high-pass filter.

For an explanation of the terms AC and DC, refer to the chapter "Analog notes ‑ dynamic signals".

The input channels can be operated in principle in the operation mode AC coupling or DC coupling, see chapter "IEPE AC Coupling":

  • AC coupling: the arbitrary input signal is fed via a high-pass filter, after which only the corresponding alternating component (AC) remains for the digital processing inside the terminal.
  • DC coupling: the arbitrary input signal is digitally processed "as it is", irrespective of whether or not it has an alternating component (AC).

The typical frequency behavior in the measuring range 2.5 V is as follows:

IEPE high pass properties 1:
IEPE high pass properties 2:
IEPE high pass properties 3:

Note: if other dynamic filter properties are desired, you can proceed as follows:

  • Operate the ELM370x terminal in the measuring range "0..20 V"
  • Deactivate IEPE AC coupling in the respective channel
    IEPE high pass properties 4:
  • The channel now measures with 23 bits + sign over 20 V, i.e. including the bias voltage, which is normally 10..16 V. With the implementation of a high-pass on the user side by means of TwinCAT programming (inside the PLC), the bias component (DC component) is now consequently to be suppressed on the controller side. The now reduced signal resolution of the measuring range ±2.5 V with 24 bits to 20 V with 23 bits must be considered. In return for that, the user obtains full digital control over the measuring behavior in the lower frequency range.