Proline Promag 53 FOUNDATION Fieldbus
14 Endress+Hauser
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Bus cable for FOUNDATION Fieldbus
The Fieldbus FOUNDATION defines four different types of cable in the specification
creating the physical transmission layer (FF-816) which is analogous to IEC 61158-2.
A two-core cable is always specified.
The electrical data has not been specified but determines important characteristics of
the design of the fieldbus, such as distances bridged, number of participants, electro-
magnetic compatibility, etc.
Two of the four cable types in the standard are specified in the following table.
We recommend the use of cables meeting the minimum requirements of type A as trans-
mission medium, particularly for the installation of new systems. The recommended net-
work expansion is made up of the length of the main cable and the length of all spurs.
The line between distribution box and field device is described as a spur. The maximum
length of a spur depends on the number of spurs (>1 m). A maximum of four field
devices can be connected to a spur.
The following table shows examples of FOUNDATION Fieldbus bus cables (type A) from
various manufacturers.
Cable type A
(reference)
Cable type B
Cable construction twisted pair, shielded one or more twisted pairs,
fully shielded
Core cross-section (nominal) 0.8 mm
2
(AWG 18) 0.32 mm
2
(AWG 22)
Loop resistance (direct current) 44 Ω/km 112 Ω/km
Impedance at 31.25 kHz 100 Ω ± 20% 100 Ω ± 30%
Attenuation constant at 39 kHz 3 dB/km 5 dB/km
Capacitive unsymmetry 2 nF/km 2 nF/km
Envelope delay distortion
(7.9...39 kHz)
1.7 µs/km **
Degree of voltage of shielding 90% **
Max. bus segment length (inc. spur lines) 1900 m 1200 m
Tab. 1: Cable types
Number of spurs 1...12 13...14 15...18 19...24 25...32
Max. length per spur 120 m 90 m 60 m 30 m 1 m
Tab. 2: Table of possible spur line lengths
Supplier Model Order number
Belden 3076 –
Kerpen FB-02YS (St+C) Y-FL 74220001 (light blue)
74220004 (black)
Siemens SIMATIC NET
bus cable
6XV1830-5AH10 (light blue)
6XV1830-5BH10 (black)
Tab. 3: Possible cable suppliers
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