Using shielding which is earthed at one end pre‐
vents low-frequency ground loops. Shielding
earthed at one end is not effective in countering
HF magnetic pick-up. Shielding earthed at both
ends as well as twisted conductors are effective in
countering magnetic HF pick-up but are not effec‐
tive against electrical HF pick-up.
We would recommend establishing a bilateral, low-inductance (i.e.
large area and low-impedance) connection with the protective
earth with PROFIBUS
®
.
The overall length of the bus cabling without repeaters varies
according to the desired data transmission rate:
Tab. 31: Data transmission rate and length of the bus cabling
Data transmission rate Maximum length of bus cabling
kBit/s m
12000 100
6000 100
3000 100
1500 200
500 400
187.5 1000
93.75 1200
19.2 1200
9.6 1200
The PROFIBUS
®
module has two M12 industrial sockets for con‐
necting with the PROFIBUS
®
cable. The pin configuration complies
with the PROFIBUS
®
standard - see below - which means that
commercially available bus plugs may be used. Please note that
cable connections made with these plugs generally only meet the
requirements for protection against contact and moisture according
to IP 20!
But:
Installation in accordance with IP 65 protection against contact and
moisture is possible, since the M12 industrial socket of the PRO‐
FIBUS
®
module allows it. But the PROFIBUS
®
cable must then be
provided with IP 65 class M12 industrial connectors.
Note for achieving IP 65 degree of
protection
Supplementary operating instructions for PROFIBUS
®
50
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