Rockwell Automation 1747-DSN DISTRIBUTED I/O SCANNER - Manual (Page 32)

Chapter 4
Operation and Troubleshooting
4–2
During normal operation, the LEDs are illuminated as shown below:
SCANNER
FAULT LED is off
COMM LED is solid green
FAULT COMM
DSN
When the SLC processor is taken out of run mode, the COMM LED remains
solid green. The inputs of the blocks connected to the scanner are still read.
However, I/O block outputs are set to 0 (disabled).
Normal Operation