pls start the goc35 by giving supply
next connect your laptop to goc by ethernet. then you wont get any ip address on it
next you switch off whole goc 35 supply
then leave some 2min
next switch on the goc35 you will get ip address ,gatway, ....etc
then you go to and set ip address in your laptop in codesys software in communication paremeter the local host address
only chang the last three numbers