CPU 416-2 for S7-400 racks
The Siemens 6ES7416-2FK04-0AB0 is a CPU 416-2 module for the S7-400 platform, handling 244 byte inputs and 244 byte outputs across the backplane. It supports CFC, FBD, LAD, SCL, STL, GRAPH, and HiGraph programming languages, so it fits into existing STEP 7 projects without recompiling the logic blocks. The FM capacity is limited by the number of slots and the number of connections — meaning the CPU can address functional modules only up to what the rack physically holds and the communication load allows. For a 9-slot UR2 rack, that's typically 8 FM slots plus the CPU itself, but the connection limit bites first if you stack multiple CPs. Mounts on a standard S7-400 rack, 25 mm wide, 290 mm tall, 219 mm deep — single-width slot.
Fieldbus and communication profile
MPI is built in for programming and HMI links. For PROFIBUS DP, you need a CP 443-5 Extended in a free slot — the CPU supports up to 10 connections via that CP. RS 485 is on the MPI port, so a simple PROFIBUS cable connects to a DP slave network if you configure it as a DP master. Routing is supported, so you can reach the CPU through a CP or IE/PB link without direct MPI access. The GSD file for PROFIBUS integration is available at the Siemens PROFIBUS GSD repository. Point-to-point connections via CP 440 are limited by slot count; CP 441 connections are limited by the number of connections. LAN communication via CP is limited by the number of connections — plan your CP count before the BOM freeze.
System functions and diagnostics
Eight SFBs are available for system functions. The CPU supports 8 RDREC, 8 WRREC, 8, 8, 8 RDSYSST (1 to 8), 8, 8, 1, 1, and 2 calls — enough for a medium-sized distributed I/O configuration with redundant parameter assignment. Forcing is supported, which lets you override process image values during commissioning without modifying the logic. The CPU can act as both a DP client and server, so it can exchange data with other DP masters on the same bus. Isolated design means the CPU backplane bus is electrically isolated from the I/O and communication circuits — reduces ground-loop noise on long PROFIBUS runs.