Hello, 

Configured the LED instruction to try and determine link status of the PLC. No matter what I align the LADDR input to, I get the same return value (9). See image for details. I have tried every port on the PLC, also tried the suggested ~common as seen in the help file. I get no change in value. 

Only thing I have successfully created an error for PLC port was to change the monitor enabled setting for the port. I then get an error anytime there is no profinet device connected here. Not exactly what I need. 

I'm simply trying to determine if my PLC has a link or not so I can enable an error routine. 

TIA portal v15 sp2 with S7-1215C firmware v4.2.2

Thank you in advanced for the help. 

Solved! Thanks Galen.

"The CPU has not supported that option for LED since the 02 versions.  The control of the Link LED was moved to the port hardware and is no longer under CPU control."

Used the Profinet Library with instruction called, LPNDR_ReadGlobalInfo. 

Key for this was to execute the block using a clock bit, and also having it point at Profinet_1 not the individual ports. Having the DataRecord point to the array [1..2] of "LPNDR_typePortLinkState", not [0..1].

I receive a 1 when linked, and a 2 when not. 

See image attached.