Contemporary Control Systems AI Active Hubs - Manual (Page 32)

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3.3 Isolating Faulty Nodes with Line Activity
Indicators
The AI has port activity indicators. Each port activity indicator
lights whenever the corresponding port on the AI receives
ARCNET signals. The intensity of these indicator lights
changes with the amount of activity and this is how defective
nodes can be isolated.
The worst possible occurrence is the “chattering node.” A
chattering node generates reconfigurations continuously, as
evidenced by the RECON light being continuously lit, because
this node has a defective receiver on its network interface
module. Under these circumstances, the port activity indicator
that corresponds to the port on the AI connected to the
chattering node will light brightly while all other port activity
indicators will appear dim. Disconnecting this cable from the AI
will extinguish the RECON indicator and return all other port
activity lights to equal brightness, thereby isolating the defective
node. For large installations, the time saved in identifying the
problem can be immense.
Port activity indicators can also point out other problems with
the network. For example, port activity indicators light up when
the AI is on and each ARCNET compatible device that is
connected to the AI is on. If a port activity indicator is not on
for a device that is properly connected to the AI, then disconnect
the cable from the port and reconnect the cable to a similar
vacant port. If the indicator on the other port does not light
when the cable is connected, check the cable, the computer or
the network interface module for possible problems.
If the port activity indicator goes on when the cable is plugged
into another port, then the problem probably lies with the
original port on the AI.
If an AI port has a line activity indicator that is on but no cable
is attached to the connector, then the port is defective and the AI
should be returned. Contact our Customer Service department.