Siemens SIMATIC 6DL1193-6AR00-0AA0 Equipment Manual page 36

Diagnostics
6.2 LED LK
Description
The LK LED indicates the following status:
LEDs "LK1" and "LK2"
ON
Off
Flashes
36
There is an Ethernet connection between the PROFINET IO interface
and a communication partner (for example, an IO controller).
There is no Ethernet connection between the PROFINET IO interface
and a communication partner (for example IO controller).
The "Node flashing test" is performed. You can use the "Node flash
test" to determine which IO controller connected on the same bus
provides a direct connection.
Meaning Solution
-
Check whether the bus cable
to the switch/IO controller is
interrupted.
-
BusAdapter for Distributed I/O
Equipment Manual, 10/2021, A5E39261458-AC