FMC Corporation - Talstar 80 - Handbuch (Seite 27)

Proline Promass 80 PROFIBUS PA Wiring
27
4.1.2 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 the spurs
(>1 m (>3 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.
4.1.3 Maximum spur length
The line between the distribution box and field device is described as a spur.
In the case of non-Ex applications, the max. length of a spur depends on the number of spurs
(>1 m) (>3 ft):
4.1.4 Number of field devices
In systems that meet FISCO with EEx ia type of protection, the line length is limited to
max. 1000 m (3280 ft). A maximum of 32 users per segment in non-Ex areas or a maximum of
10 users in an Ex-area (EEx ia IIC) is possible. The actual number of users must be determined
during configuration.
4.1.5 Bus termination
The start and end of each fieldbus segment are always to be terminated with a bus terminator. With
various junction boxes (non-Ex), the bus termination can be activated via a switch. If this is not the
case, a separate bus terminator must be installed.
Note the following points:
• In the case of a branched bus segment, the device furthest from the segment coupler represents
the end of the bus.
• If the fieldbus is extended with a repeater then the extension must also be terminated at both
ends.
4.1.6 Further information
General information and further notes regarding the wiring are contained in BA034S/04:
"Guidelines for planning and commissioning, PROFIBUS DP/PA, field communication."
Type A 1900 m 6200 ft
Type B 1200 m 4000 ft
Number of spurs 1 to 12 13 to 14 15 to 18 19 to 24 25 to 32
Max. length per spur
[m] 120 90 60 30 1
[ft] 400 300 200 100 3