Rockwell Automation 1797-Series ControlNet Ex Media Plannng Installation Manual - Manual (Page 32)

Publication CNET-IN003A-EN-P - January 2006
2-10 Plan a ControlNet Ex Media System
Use Redundant Media in a
Hazardous Area You can run a second trunk cable between your ControlNet Ex nodes
for redundant media. With redundant media, nodes send signals on
two separate segments. The receiving node compares the quality of
the two signals and accepts the better signal to permit use of the best
signal. This also provides a backup cable should one cable fail.
Trunk cables on a redundant cable network are defined by the
segment number and the redundant trunk cable letter.
Actual ControlNet Ex products are labeled with these icons
(the shaded icon represent redundant media).
In this figure, the redundant cable trunk cable is trunk cable B.
Observe the following guidelines when planning a redundant media
system in a hazardous area.
•
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 network 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 network will result in media errors on the
unconnected trunk cable.
1
.
.
.
.
1 2 4 3 +V -V +V -V
Q UAL IT Y B - A Allen-Bradley 1797 - RPA
ControlNet E x REPEATER ADAPTER Comm
Status Module
Status PWR
.
.
.
Recv Xmit Recv Xmit
Chan 2 Chan 1
1797 - RPFM Q UAL I TY B - A Allen-Bradley
ControlNet E x FIBER MODULE
MEDIUM RANGE
.
1
.
.
.
.
1 2 4 3 +V -V +V -V
Q UAL IT Y B - A Allen-Bradley 1797 - RPA
ControlNet E x REPEATER ADAPTER Comm
Status Module
Status PWR
.
.
.
Recv Xmit Recv Xmit
Chan 2 Chan 1
1797 - RPFM Q UAL I TY B - A Allen-Bradley
ControlNet E x FIBER MODULE
MEDIUM RANGE
.
1
.
.
.
.
1 2 4 3 +V -V +V -V
Q UAL IT Y B - A Allen-Bradley 1797 - RPA
ControlNet E x REPEATER ADAPTER Comm
Status Module
Status PWR
.
.
.
Recv Xmit Recv Xmit
Chan 2 Chan 1
1797 - RPFM Q UAL I TY B - A Allen-Bradley
ControlNet E x FIBER MODULE
MEDIUM RANGE
.
1
.
.
.
.
1 2 4 3 +V -V +V -V
Q UAL IT Y B - A Allen-Bradley 1797 - RPA
ControlNet E x REPEATER ADAPTER Comm
Status Module
Status PWR
.
.
.
Recv Xmit Recv Xmit
Chan 2 Chan 1
1797 - RPFM Q UAL I TY B - A Allen-Bradley
ControlNet E x FIBER MODULE
MEDIUM RANGE
.
Trunk Cable A =
Trunk Cable B =
41346
Node
1797 Fiber
Repeater Hub 1786 Fiber
Repeater Hub
Safe Area Hazardous Area
1797 Fiber
Repeater Hub 1786 Fiber
Repeater Hub
Coax Trunk Cable A =
Coax Trunk Cable B =