Identifying And Correcting Errors In Slaves - Omron NT-DRT21 Operation Manual

Troubleshooting with the LED Indicators

8-2-2 Identifying and Correcting Errors in Slaves

MS LED NS LED
Lit Lit Remote I/O
(green) (green) communications or
message
communications in
progress
Lit Not lit Checking for node
(green) number duplication
Lit Flashing Waiting to connect
(green) (green)
Lit (red) Not lit Watchdog timer error
Flashing Not lit Incorrect switch settings
(red)
Lit Lit (red) Node number duplication A node number is
(green)
Lit Lit (red) Busoff detected
(green)
Lit Flashing Communications timeout ---
(green) (red)
110
Meaning
Remote I/O
communications in
progress or message
communications being
executed
Waiting for the Master's
node number duplication
check
Waiting for connection to
be established from the
Master
A watchdog timer error
occurred at the Slave.
Incorrect switch settings
such as the DIP switch
duplicated with the
Master Unit.
Bus Off status
(communications
stopped due to multiple
data errors)
Section
Remarks
Remote I/O communications, message
communications, or both are being
executed. Indicates normal communications
status.
When the local Slave (PT) is the only Slave
in this status, check the communications
speed setting and restart the PT.
---
Replace the Slave (DeviceNet Interface
Unit).
Check the DeviceNet memory switch
settings and restart the PT.
Reset the node numbers to eliminate
duplication and restart the Slave.
Check the following points and restart the
Slave (PT).
• Are the Master and Slave (DeviceNet Inter-
face Unit) communications speeds the
same?
• Are the cable lengths (trunk and branches)
within specifications?
• Are any cables disconnected, damaged, or
loose?
• Are termination resistors connected only at
each end of the trunk line?
• Is noise excessive?
Check the following points and restart the
Slave (PT).
• Are the Master and Slave (DeviceNet Inter-
face Unit) communications speeds the
same?
• Are the cable lengths (trunk and branches)
within specifications?
• Are any cables disconnected, damaged, or
loose?
• Are termination resistors connected only at
each end of the trunk line?
• Is noise excessive?
8-2