Fig. 32 Principle Of Combining Two Measuring Channels With Fsv1 And Fsv2 - Beckhoff EPP3504-0023 Short Manual

Commissioning
Fig. 32: Principle of combining two measuring channels with FSV1 and FSV2
The dynamic range of a typical 24-bit voltage or current measurement range with the absolute PDO end
23 23
value of 2 (bit 24 is sign) is 20 · log(2 ) ≈ 138.5 dB (without consideration of measurement uncertainties).
Now it is possible to connect two (or more) inputs of a measuring system of the same measurement type
with different measurement range end values (FSV1, FSV2, FSVn) in parallel to increase the dynamic range.
The measured input value is then logged with two measuring ranges FSV1 and FSV2 through combination
of two inputs. If FSV2 < FSV1 is selected and thus a lower resolution of FSV2 than FSV1, the low resolution
of FSV2 is available if the magnitude of the measured input value is <= FSV2, and the measured input value
can also be acquired for the larger range up to <= FSV1.
Note: The general definition is used to calculate the dynamic range:
Dynamic range = largest measured value / smallest unit
For output in dB accordingly with 20 · log(FSV / Resolution ). In this sample, using a combination of FSV1
FSV
and FSV2, the calculation is as follows:
Dynamic range = 20 · log(FSV1 / Resolution ).
FSV2
The following sample program is based on a parallel connection of two input channels of the ELM3602-0002:
108 Version: 1.2 EPP3504-0023