You should always use metallic or metallised covers for serial data
lines. Connect the screen of the data line to the cover. Do
not
con-
nect the screen to PIN 1 of the connector! In case of stationary opera-
tions it is recommended that the remove the insulation from the
screened cable without cutting the screen and to attach this point to
the screening/neutral rail.
Potential differences can give rise to an equalization cur-
rent via the screen connected between the two ground
connections. In this case you must install an additional
equipotential bonding conductor.
Please observe the following points when you handle the screens:
n
Use only metallic cable clamps when connecting the screening of
cables. These clamps must provide a good electrical contact and
a large-surface connection to the screen.
n
Attach the screens to the screening rail directly at the point where
the cables enter the enclosure. The screening conductor must be
continued to the module without interruption, however, it must not
be connected to the module!
5.4 Special precautions providing high noise immunity
Inductors controlled by your programmable controller (e.g. contactors
and relays) do not normally require additional snubber networks or
suppressors as the respective modules have been provided with the
required components.
Snubber networks must only be connected to inductors when output
circuits can be disabled by means of additional contacts (e.g. relay
contacts). In this case the integrated suppressors on the module are
also disabled. You can connect diodes to suppress back-emc, varis-
tors or RC-networks to the inductors.
Connecting the screen
Inductors require
snubber networks
Equipotential bonding
VIPA HMI PPC021 CE
Installation guidelines
Special precautions providing high noise immunity
HB160 | PPC | 67S-PNJ0 | GB | 15-30
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