4.4 Installation
All devices that are members of the bus system, must be con‐
nected in a line. There are up to 32 possible positions (master,
slaves, repeaters).
At both the beginning and end of the cable, the bus must be termi‐
nated with a terminating resistance.
For the PROFIBUS
®
cable, use a shielded, twisted-pair cable in
conformity with EN 50170 (cable type A).
Use of screening which is earthed at one end pre‐
vents low-frequency ground loops. Shielding
earthed at one end has no effect in combating HF
magnetic pick-up. Shielding earthed at both ends
as well as twisted conductors work to counter mag‐
netic HF pick-up, but have no effect against elec‐
trical HF pick-up.
For PROFIBUS
®
, it is recommended that a bilateral, low-induc‐
tance (i.e. large area and low-impedance) connection is estab‐
lished with the protective earth.
The overall length of the bus cabling without repeaters varies
according to the desired data transmission rate:
Tab. 33: Data transmission rate and length of the bus cabling
Data transmission rate Max. 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 industry 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 are generally only con‐
tact and moisture proof to IP 20!
Installation to IP 65 contact and moisture proofing level is possible,
since the M12 industry socket of the PROFIBUS
®
module allows it.
Accordingly, the PROFIBUS
®
cable must be provided with IP 65
class M12 industrial connectors.
Bus installation
Plugs and cable
Note for achieving IP 65 protection
Supplementary Operating Instructions PROFIBUS
®
69
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