Rockwell Automation AutoMax R-Net Processor Module - Manual (Page 30)

5Ć2
5.3 Communication Line Failure
Problem: The top and/or bottom red LEDs on the module faceplate
flash on and off. This indicates a CRC error or lost token timeout,
respectively, signaling a communication line failure. The RECV LED
may also be off indicating a communication line failure. The cause of
a communication failure is a lack of integrity along the high speed
line. Error parameters (RECEIVE TIMEOUTS, CRC, OVERRUN,
ILLEGAL MESSAGE, LOST TOKEN) are logged in the AutoMax RĆNet
module's status and control registers. A few errors may accumulate
over a period of time, such as a few days; but, when these parameter
values increase consistently over a short period of time, there is a
problem with the integrity. Use the following procedure to isolate the
cause of a communication failure:
Step 1.
Verify the node number is unique and the rotary switches
are set correctly. Verify the switch settings on the module
correspond to the node number value in register 12. The
AutoMax RĆNet module reads the value of these switches
only at powerĆup. If any changes are made to the
switches, you must cycle power to the rack in order for the
new settings to be recorded in this register.
Step 2. Verify the network connections to each module are secure.
Check the connection between the BNC connector on the
faceplate and the Tee connector. Check the connection
between the Tee connector and the coax cable.
Step 3. Verify the network cabling is terminated correctly. There
must be a line terminator at each end of the network.
Step 4. Verify that the network cabling does not exceed the
maximum allowable length given its electrical
characteristics.
Step 5. Verify a minimum network cable length of 50 feet between
any two nodes.
Step 6. Verify the cable installation between nodes conforms to
the guidelines described in the RĆNet Cable Installation
Manual (J2Ć3009) to inhibit excessive noise disturbances.
Verify the cable between nodes is not kinked or severed.