Configuration Manual Owner manual

Publication 1757-PM002A-EN-E - June 2006
Set Up A System 2-3
resistive/inductive network that is either external or built into the fieldbus
power supply.
Fieldbus Cable
The preferred fieldbus cable is specified in the IEC/ISA Physical Layer
Standard, Clause 22.7.2 for conformance testing. It is referred to as type “A”
fieldbus cable. This cable will probably be used in new installations.
Other types of cable can also be used. The alternate preferred fieldbus cable is
a multiple, twisted pair cable with an overall shield. It is referred to as Type
“B” cable. Less preferable types of cable include single or multiple twisted pair
cable without any shield, referred to as Type “C” cable, and multiple conductor
cable without twisted pairs, but with overall shield, referred to as Type “D”
cable.
The following table contains the types of cable identified by the IEC/ISA
Physical Layer Standard and their maximum length values. For information
about spur wire length, see the
Spur Wire Length Calculations section on
page 2-9.
Devices
Fieldbus links smart field devices with automation systems. The devices
generally used in fieldbus networks are type 113 (bus powered) or type 114
(separate power). Examples of these devices are the Rosemount 3051S
pressure Transmitter and the Micro Motion 2700 Flowmeter.
Type Cable Description Size Maximum Length
Type A Shielded, twisted
pair
#22 AWG
(.8 mm
2
)
1900 m
(6232 ft.)
Type B Multi-twisted pair
with shield
#22 AWG
(.32 mm
2
)
1200 m
(3936 ft.)
Type C Multi-twisted pair
without shield
#26 AWG
(.13 mm
2
)
400 m
(1312 ft.)
Type D Multi-core, without
twisted pairs and
having an overall
shield
#16 AWG
(1.25 mm
2
)
200 m
(656 ft.)