4 Wiring Promag 53 PROFIBUS-DP/-PA
48 Endress+Hauser
4.1.2 PROFIBUS-PA: Cable specifications
Cable type
Twin-core cable is required for connecting the device to the fieldbus. By analogy with
IEC 61158-2 protocol four different cable types (A, B, C, D) can be used with PROFIBUS
protocol, only two of which (cable types A and B) are shielded.
• Cable types A or B are particularly preferable for new installations. Only these types
have cable shielding that guarantees adequate protection from electromagnetic inter-
ference and thus the most reliable data transfer. On multi-pair cables (Type B), it is
permissible to operate multiple fieldbuses (with the same degree of protection) on one
cable. No other circuits are permissible in the same cable.
• Practical experience has shown that cable types C and D should not be used due to
the lack of shielding, since the freedom from interference generally does not meet the
requirements described in the standard.
The electrical data of the fieldbus cable has not been specified but determines impor-
tant characteristics of the design of the fieldbus, such as distances bridged, number of
participants, electromagnetic compatibility, etc.
Suitable fieldbus cables from various manufacturers for the non-hazardous area are
listed below:
• Siemens: 6XV1 830-5BH10
• Belden: 3076F
• Kerpen: CeL-PE/OSCR/PVC/FRLA FB-02YS(ST)YFL
Cable type A Cable type B
Cable structure twisted pair, shielded one or more twisted pairs,
fully shielded
Wire size 0.8 mm
2
(AWG 18) 0.32 mm
2
(AWG 22)
Loop resistance (DC) 44
Ω/km 112 Ω/km
Impedance at 31.25 kHz 100
Ω ± 20% 100 Ω ± 30%
Attenuation at 39 kHz 3 dB/km 5 dB/km
Capacitive asymmetry 2 nF/km 2 nF/km
Envelope delay distortion (7.9
through 39 kHz)
1.7
µs/km *
Shield coverage 90% *
Max. cable length (inc. spurs >1 m) 1900 m 1200 m
* not specified
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