TESTO 6681 Profibus Instruction Manual page 47

Shielding
To safeguard the Profibus from electromagnetic influences, you should
use shielded cable type A data cables (see chapter 1.3.4.1, page 44).
route the bus cables as far away from all live cables as possible.
connect the double-sided cable shield to each connective bus subscriber.
ensure optimum equipotential bonding between the individual bus
subscribers (e.g. by means of equipotential bonding line/common
earthing bar).
Without equipotential bonding the differences in potential may
lead to low-frequency equalizing currents and, in extreme
cases, to destruction of the cables.
If no equipotential bonding can be ensured within the system,
we recommend only applying the shield on one side and
establishing capacitive connections for all further earthing
points.
Use of the external earthing terminal only in interiors
testo 6681 Profibus
- 1.3 Commissioning 47
1 Equipotential
bonding strip
2 Equipotential
bonding line
3 Data cable
4 Transmitter
(slave)
5 Master