Rockwell Automation 2098-IPD-020-DN Ultra5000 Series Intelligent Positioning Drives with DeviceNet Reference Manual - Manual (Page 81)

Publication 2098-RM002A-EN-P – October 2001
Troubleshooting DeviceNet Drives 5-3
Node Problems
Give particular attention to the task of setting initial addresses and
data rates. Survey the network to ensure all assignments are known.
Some nodes can be logically assigned to a group of devices, but
physically located away from those devices. One incorrect node can
cause other nodes to appear to be bus-off (steady-red Network Status
LED). If a node goes bus-off and the device is reset but bus-off faults
again, the problem is likely not with the device. The problem is likely
to be the setting of the address, data rate, or a network-wide problem
related to topology, grounding, intermittent power/data connections,
or electrical noise. In the event that a scanner goes bus-off, nodes will
not reallocate (flashing-green or red) even if they are functioning
correctly.
Device Failure - LED Status
Check
A steady-red Module Status LED can mean an error. If the Network
Status LED goes steady-red at power-up, it could mean there is a
Duplicate MAC ID. The user response is to test all devices for unique
addresses. If a steady-red LED remains on after the Duplicate MAC ID
test shows all devices to have a unique node address, it means a
Bus-off error. Do the following:
• Check data rate settings.
• If symptom persists, replace node address (with another address
and correct data rate).
• If symptom persists, replace tee tap.
• If symptom persists, check topology.
• If symptom persists, check power for noise with oscilloscope or
power disturbance analyzer.