SIMATIC S7- 400H High-availability CPUs

Increase system availability and productivity


The flexible insurance against downtimes
Regardless of the industry, cost pressure and the demand for maximum productivity are ratcheting up automation levels in production plants. This means that economic effectiveness depends directly on the availability of the systems, that is, the automation components used.
To retain productivity, regular maintenance and modernization work needs to be performed through the lifecycle of a plant/machine. For this reason alone, the ideal availability of 100% cannot be attained in practice.
However, with SIMATIC S7-400H, Siemens offers a highly available controller which minimizes the probability of production failures – and thus decisively contributes to maximum productivity.

All innovated CPUs of series -5H have 5 interfaces:
1 PROFINET DP interface
1 MPI-/PROFIBUS DP interface
2 interfaces for sync-modules
1 PROFINET interface with 2-port-switch

All CPUs enables optional Safety and can be used in maximum of 10km distance
between 2 CPUs

SIMATIC S7-400 CPU 412-5H

CPU 412-5H

CPU with a medium program memory and quantity framework

  • RAM 1 MB

SIMATIC S7-400 CPU 414-5H

CPU 414-5H

CPU for more demanding applications of the medium performance range and additional communication tasks

  • RAM 4 MB

SIMATIC S7-400 CPU 416-5H

CPU 416-5H

Entry CPU for the upper performance range

  • RAM 16 MB

SIMATIC S7-400 CPU 417-5H

CPU 417-5H

High End CPU for the upper performance range and additional PROFIBUS communication tasks

  • RAM 32 MB


  • Highest system availability with early fault detection and integrated diagnostic capabilities

  • Efficient solutions with scalable performance and redundancy

  • Simple programming and configuration

  • Performance-oriented solution for time-critical processes

  • Synchronized hardware solution without information loss

  • Highly available communication via Industrial Ethernet

  • Integrated diagnostic functions

  • Exchange of all components during operation

  • SIMATIC S7-400H CPUs can be extended with safety functionality in the case of need

  • Many of the S7-400H components are also available in a SIPLUS version for extreme environmental conditions, e.g. for use where there is an corrosive atmosphere / condensation.


  • Power generation and distribution

  • Chemical industry and petrochemicals

  • Oil, Gas

  • Refineries

  • Pharmaceuticals

  • Airport automation

  • Waterworks and water treatment plants

  • Transport technology

  • Traffic flow automation

  • Shipbuilding

  • Turbine development

Design and function

The SIMATIC S7-400H suitable as a controller for high-availability processes, with two H CPUs of the same type; in the event of a fault, changeover takes place from the master system to the standby station. The method of event-driven synchronization supports fast and bumpless changeover to the redundant CPU in the event of a fault. It resumes processing at the point of interruption without any loss of information or interrupts.All components can be replaced during normal operation (hot swapping). When a CPU is replaced, all the current programs and data are automatically reloaded. The SIMATIC S7-400H is suitable for high-availability processes with hot standby requirements (processes with changeover times shorter than 100 ms).

The central devices can be configured in two different ways:

  • When the subunits have to be completely separated from each other for availability reasons, it is appropriate to use two standard racks (UR1 and UR2). Each rack accommodates one CPU and one power supply (PS). If extremely high availability is required, two redundant power supply modules can be used. The distance between the two racks can be up to 10 km.

  • Two CPUs, each with either a single or a redundant power supply, are plugged into the UR2-H rack with a segmented backplane bus. This supports an extremely compact configuration.

I/O and communication
Maximum availability is not absolutely perfect until it can be matched exactly to your needs. We offer I/O that can be configured and operated redundantly. These modules can be configured in separate racks – or also in the same rack – with a simple or redundant PROFIBUS/PROFINET connection. Maximum availability also applies to communication. Depending on the network topology, redundant connections are created to which it is possible to switch over in the event of a failure. When a failure occurs, fault-tolerant communication is automatically continued without any problems being noticeable to the user.The I/O can be connected to suit the availability requirements.The following types of connection are available:

  1. Single-sided connection (normal availability) for all PROFIBUS slaves, e.g. ET 200M, ET 200S, ET 200eco

  2. Switched connection (increased availability) for ET 200M

  3. Redundant connection (fault-tolerant) for ET 200M. These configurations can also be mixed

These configurations can be mixed.

Programming is possible, as in the case of a standard system, in all STEP 7 programming languages. The programs can easily be ported from standard systems to a redundant system and vice-versa. When the program is loaded, it is automatically distributed onto the two redundant CPUs. The functions and configurations specific to redundancy are parameterized using the S7 H-Systems option package (integrated into STEP 7 Version 5.3 or higher). The planning engineer is free to concentrate solely on controlling the process.

Diagnostics / Module replacement
Apart from the standard diagnostic functions, the following functions are also available:

  • With the integrated self-diagnostics functions, the system detects and signals errors before they can affect the process. They enable the faulty components to be identified and replaced quickly which speeds up repairs.

  • All components can be replaced during normal operation (online repair). When a CPU is replaced, all the current programs and data are automatically reloaded. It is also possible to modify the program during normal operation, e.g. changing and reloading function blocks.

  • Changes can also be made to the configuration during normal operation, e.g. adding or removing of DP slaves or modules, changing the memory configuration of the CPU.

Technical data

Technical data S7-400 H-CPUs

Technical data S7-400 H-CPUs

Technical data S7-400H Innovations

Technical data S7-400H H-CPUs series -5H