RID16
Wiring
Hauser
15
4.3
FOUNDATION Fieldbus™ cable specification
4.3.1
Cable type
Twin-core cables are required for connecting the device to the FOUNDATION Fieldbus™ H1.
Following IEC 61158-2 (MBP), four different cable types (A, B, C, D) can be used with the
FOUNDATION Fieldbus™, 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 interference and thus the
most reliable data transfer. In the case of cable type B, several field buses (same degree of
protection) may be operated in 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 have not been specified but determine important
characteristics of the design of the fieldbus, such as distances bridged, number of users,
electromagnetic compatibility, etc.
Suitable fieldbus cables (type A) from various manufacturers for non-hazardous areas are listed
below:
• Siemens: 6XV1 830-5BH10
• Belden: 3076F
• Kerpen: CeL-PE/OSCR/PVC/FRLA FB-02YS(ST)YFL
4.3.2
Maximum overall cable length
The maximum network expansion depends on the type of protection and the cable specifications.
The overall cable length combines the length of the main cable and the length of all spurs (>1 m/
3.28 ft). Note the following points:
• The maximum permissible overall cable length depends on the cable type used.
• If repeaters are used, the maximum permissible cable length is doubled. A maximum of three
repeaters are permitted between user and master.
Type A
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 (direct current)
44
Ω
/km
112
Ω
/km
Characteristic impedance at 31.25
kHz
100
Ω
± 20%
100
Ω
± 30%
Attenuation constant at 39 kHz
3 dB/km
5 dB/km
Capacitive asymmetry
2 nF/km
2 nF/km
Envelope delay distortion (7.9 to 39
kHz)
1.7 ms/km
*
Shield coverage
90%
*
Max. cable length (incl. spurs >1 m)
1900 m (6233 ft)
1200 m (3937 ft)
* Not specified
