Hello, the RDW on KRC2 KR16 is not the same as on KRC4 KR16 and you wont be able to connect KRC2 KR16 to KRC4, you can try and maybe exchange KRC2 RDW to KRC4 RDW box and connectors from resolvers, mechanically i think the robot manipulators are the same KRC2 KR16 and KRC4 KR16 to match machine data, but i'm not sure, would have to check, because there is also KR16-2 version.