6-3
Section 6 F
OUNDATION
Fieldbus Guidelines
Installation and Operation Manual
X-DPT-FF-MT3809G-Alarms-eng
Part Number: 541B218AAG
December, 2017
Model MT3809G F
OUNDATION
TM
Fieldbus
Figure 6-4 Adding a Repeater to the Fieldbus Network
four devices, one of them being the repeater. The second trunk has two
devices, one of them being the repeater. You can use up to four repeaters in
series between any two devices to get a total length of 9500 (31167.98 ft.)
In addition to increasing the length of a network, repeaters can be used to
increase the number of devices in a network beyond the limit of 32 on one
segment. Using repeaters, the maximum number of devices in a network
could be increased to 240.
Shielding (screening)
A fieldbus network can bu built using only unshielded wire pairs. If these
are placed in conduit or laid against a metal surface, there may be
sufficient shielding that nothing further need be done.
However, for best performance, fildbus cables should be shielded.
Common multi-conductor (multi-core) "instrument" cable can be used. This
has one or more twisted pairs, an overall, metalized shield, and a shield
wire.
Figure 6-5 Use of Shielded Cable
FD
FD
FD
FD
F
OUNDATION
Fieldbus
Interface
FFI
FD = Field Device
T
T
T
T
2nd Trunk
1st Trunk
Repeater
F
OUNDATION
Fieldbus
Interface
FFI
T
T
FD
FD
FD
FD
FD = Field Device
