ControlNet NetChecker
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Rockwell Automation Publication 1788-UM001B-EN-P - August 2012
When you press the ON switch, the TRAFFIC status indicator should turn green to indicate
that messages are being detected. The greater the volume of traffic seen on the network, the
brighter the status indicator will be illuminated. If the status indicator remains off, the network is
either inactive or the tested segment of cable is disconnected from the network. Check the cable
and the connectors.
Select Testpoints on the Network
Good diagnostic results verify that the network signal is clean at the
point of test
only. Because
the defects caused by a single impedance mismatch are variable along the cable
and are also
related to the node that is transmitting,
a network segment should be tested at several points.
For example, test near the two ends of the cable and at one or more points along the cable,
depending on the cable length and the number of nodes. If repeaters are used, every segment
between repeaters should be checked. On a redundant network, check both of the cables.
The NetChecker can indicate that there is a problem on the tested network, but it cannot
indicate where
the problem originated. However, it can help to locate intermittent defects, as
described in
. Keep in mind that the source of a problem may be far
away from the point of analysis.
Network Diagnostics
This section describes procedures for evaluating the quality of the ControlNet network.
How to Begin Checking Your Network
Start checking in Diagnostic mode. You can start checking at any of the three threshold settings
(L, M, and H), but be sure to perform the test at all three settings. Then set SW3 to the bargraph
(rightmost) position and examine the global signal level on the network by setting the Node
Finder thumbwheels to 00.
If you obtained the following results, the NetChecker did not detect any problem at the
testpoint.
Refer to the table in the following section to determine the overall state of your network.
TIP
A bad diagnostic result does not necessarily mean that the network is not functional. However,
it may require a closer check of system components, such as wiring, component quality,
connectors, and impedance matching.
Status Indicator
State
TRAFFIC
Green
Pass/Fail
Green
Fault
All Off
Buzzer
Does not sound
Bargraph indication
Within range of 2…6
for all thresholds: L, M, H
