Hello,

The attached snap seems to be of PCU20.

Please check 840D NCU number, it is printed on sticker which is pasted on the top left side of NCU. This NCU number is helpful to find out type of PLC-CPU integrated in NCU unit. You can communicate & modify PLC program by connecting PG/PC with Simatic Manager Step 7 v 5.x software with CP5611 & MPI data interface cable.

HTH

6FC5247-0AA00 It is not NCU. It is NCU box. 

Please check number on top left side. It will be of NCU number.

Also attach clear nameplate snap of mmc part which you attached in your first post. 

NCU 561.3 - Integrated PLC CPU is 315-2DP

You need PG/PC with CP MPI port & MPI cable with Simatic Manager Step 7 v (5.4 atleast) to go on line, modify PLC program.

HTH