What you should know about analog technology
2.14 Diagnostics
Analog value processing
Function Manual, 06/2014, A5E03461439-AC
43
Common mode error
Activating the "Common mode" checkbox diagnoses a violation of the maximum potential
difference U
CM
. A violation of the permitted potential difference U
CM
has occurred, for
example, between the reference point of the measuring inputs and the analog ground M
ANA
.
Possible causes:
●
Wiring error
●
Environments with EMC disturbance
●
Incorrectly grounded transducers
●
Long line lengths
●
Sensor not connected
●
2-wire transducer connected to M
ANA
Note
With 4-wire transducers, a current meter connected in series will result in too great a drop in
voltage.
Potential differences U
CM
beyond the valid limits may lead to measurement errors and
malfunctions. If you want to ensure that the maximum value is not exceeded, interconnect
the measuring inputs and analog ground M
ANA
with an equipotential bonding cable. More
detailed information can be found in Wiring transducers.
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