Rockwell Automation Allen-Bradley ControlNet 1786 Series, Руководство по установке

Страница: 29 / 74

Publication CNET-IN002A-EN-P - December 2001
Plan a ControlNet Coax Media System 2-13
Observe these guidelines when planning a redundant media system.
•
Route the two trunk cables (trunk cable A and trunk cable B)
differently to reduce the chance of both cables being damaged
at the same time.
•
Each node on a redundant-cable link must support redundant
Coax connections and be connected to both trunk cables at all
times. Any nodes connected to only one side of a
redundant-cable link will result in media errors on the
unconnected trunk cable.
•
Install the cable system so that the trunk cables at any physical
device location can be easily identified and labeled with the
appropriate icon or letter. Each redundant ControlNet device is
labeled so you can connect it to the corresponding trunk cable.
•
Both trunk cables (trunk cable A and trunk cable B) of a
redundant-cable link must have identical configurations.
Each segment must contain the same number of taps, nodes and
repeaters. Connect nodes and repeaters in the same relative
sequence on both trunk cables.
•
Install cable on each side of a redundant cable so that each
cable is about the same length. The total difference in length
between the two trunk cables of a redundant-cable link goes
down as the number of repeaters increases.
Allow a b le Ca b le L e ng th Diffe re n ce vs. Re p e a te rs in S e rie s
for Co a x M e dia
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350 400 450
Allowable C oax C able Le ngth D iffe re nce (me te rs)
R
e
p
eat
er
s in
Se
ri
e
s
W ors t Cas e
Ty pic al Cas e
Allo w a b le Ca b le L e n g th Diffe re n ce vs. Re p e a te rs in S e rie s
fo r F ib e r M e d ia
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350 400 450
Allowable Fibe r C able Le ngth D iffe re nce (me te rs)
R
e
p
e
a
ter
s in
Se
ri
e
s
W ors t Cas e
Ty pic al Cas e