The CPU 412-3H has:

• A powerful processor:
  The CPU achieves command runtimes as low as 75 ns per binary command.
• 768 KB RAM (512 KB for program, 256 KB for data);
  Load memory for user programs and parameterization data of the S7-400H F/FH automation system; high-speed RAM for sequence-relevant sections of the user program
• A memory card:
  For expanding the integrated load memory. The load memory contains the parameterization data of the S7-400H F/FH as well as the program, and therefore requires approximately double the memory space . The result is that:
  • The integrated load memory is not sufficient for large programs, which is why the memory card is often required.
    RAM and FEPROM cards are available (FEPROM for saving at zero voltage too).
• Easy expandability:
  Max. 65K digital and 4K analog inputs/outputs.
• Combined MPI/PROFIBUS DP interface:
  The MPI enables the creation of a simple network with max. 32 nodes and a data transfer rate of 187.5 Kbit/s. The CPU can establish up to 64 connections to nodes on the communication bus (C bus) and the MPI.
  The PROFIBUS DP master interface enables a distributed automation configuration with high speed and simple handling. From the user's point of view, the distributed I/Os are treated like centralized I/Os (same configuration, addressing and programming).
• Mode selector:
  Designed as a toggle switch.
• Diagnostics buffer:
  The last 120 alarm and interrupt events are stored in a ring buffer for diagnostics purposes.
• Real-time clock:
  Diagnostics messages from the CPU are provided with the date and time of day.