8-2
Section
Troubleshooting with the LED Indicators
110
8-2-2 Identifying and Correcting Errors in Slaves
MS LED
NS LED
Meaning
Remarks
Lit
(green)
Lit
(green)
Remote I/O
communications or
message
communications in
progress
Remote I/O
communications in
progress or message
communications being
executed
Remote I/O communications, message
communications, or both are being
executed. Indicates normal communications
status.
Lit
(green)
Not lit
Checking for node
number duplication
Waiting for the Master’s
node number duplication
check
When the local Slave (PT) is the only Slave
in this status, check the communications
speed setting and restart the PT.
Lit
(green)
Flashing
(green)
Waiting to connect
Waiting for connection to
be established from the
Master
---
Lit (red)
Not lit
Watchdog timer error
A watchdog timer error
occurred at the Slave.
Replace the Slave (DeviceNet Interface
Unit).
Flashing
(red)
Not lit
Incorrect switch settings
Incorrect switch settings
such as the DIP switch
Check the DeviceNet memory switch
settings and restart the PT.
Lit
(green)
Lit (red)
Node number duplication A node number is
duplicated with the
Master Unit.
Reset the node numbers to eliminate
duplication and restart the Slave.
Lit
(green)
Lit (red)
Busoff detected
Bus Off status
(communications
stopped due to multiple
data errors)
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?
Lit
(green)
Flashing
(red)
Communications timeout
---
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?