The SIMATIC S7-400 is available in several versions:

• S7-400:
  The power PLC for the mid to high-end performance ranges with modular, fan-free design.
• S7-400H:
  Fault-tolerant automation system with redundant design for fail-safe applications.
• S7-400F/FH:
  Fail-safe automation system with redundant design that can also have high availability.

S7-400

The S7-400 automation system is modular in design. It has a comprehensive range of modules that can be combined individually.

A system includes the following:

• Power supply module (PS):
  for connecting the SIMATIC S7-400 to a supply voltage of 120/230 V AC or 24 V DC.
• CPUs:
  Different CPUs with integral PROFIBUS DP interfaces are available for different performance ranges. Depending on type, they are also available with integral PROFINET interface. The PROFIBUS interface enables the connection of up to 125 PROFIBUS DP slaves. Up to 256 PROFINET IO devices can be connected to the PROFINET interface. All CPUs of the SIMATIC S7-400 can handle extremely large configurations. In addition, several CPUs can work together in multicomputing in one central controller to increase performance. The CPUs enable short machine cycle times by means of their efficient processing speed and deterministic response times.
• Signal modules (SMs) for digital (DI/DO) and analog (AI/AO) input/output
• Communications processors (CPs), e.g. for bus connection and point-to-point connections
• Function modules (FMs):
  The specialists for demanding tasks such as counting, positioning and cam control.

The following can also be used depending on requirements:

• Interface modules (IMs):
  for connecting central controllers and expansion units. The central controller of the SIMATIC S7-400 can be operated with up to 21 expansion units.
• SIMATIC S5 modules:
  All input/output modules of the SIMATIC S5-115U/-135U/-155U can be addressed in the relevant SIMATIC S5 expansion units. In addition, the use of certain IP and WF modules of the SIMATIC S5 is possible both in S5 EUs and direct in the CC (using adapter casing).

Expansion

If users require more than one central controller for their applications, the S7-400 can be expanded:

• Max. 21 expansion units:
  Up to 21 expansion units (EUs) can be connected to the central controller (CC).
• Connection of the interface modules (IMs):
  The CC and EUs are connected via send and receive IMs. Send IMs are plugged into the CC, and the associated receive IMs are plugged into the downstream EUs. Up to 6 send IMs can be plugged into the CC (of which up to 2 with 5-V transfer), and up to 1 receive IM can be plugged into the EUs. Each send IM has 2 interfaces for connecting one line each. Up to 4 EUs (without 5-V transfer) or 1 EU (with 5-V transfer) can be connected to each interface of a send IM.
• Fixed slot for power supply modules:
  Power supply modules must always be plugged in on the extreme left in the CC and EUs.
• Restricted data exchange via C bus:
  Data exchange via the C bus only between the CC and six EUs (EU 1 to EU 6).
• Central expansion:
  To be recommended for smaller setups or control cabinets direct at the machine. The 5-V power can optionally also be supplied.
  • Max. distance between CC and the last EU of a line: 1.5 m with 5 V transfer, 3 m without 5 V transfer.
• Distributed expansion with EUs:
  Recommended in plants covering a large area where several EUs are located at individual locations. Up to S7-400 EUs or SIMATIC S5 EUs can be used.
  • Max. distance between CC and the last EU of a line: approx. 100 m with S7 EU, 600 m with S5 EU.
• Note For distributed connection of S5 expansion units to an S7-400:
  The IM 463-2 can be used in the CC of the S7-400, and an IM 314 is used in the S5 EU. The following S5 EUs can be connected to an S7-400:
  • EG 183U
  • EG 185U
  • EG 186U
  • ER 701-2
  • ER 701-3

• Distributed expansion with ET 200:
  recommended for plants covering extremely large areas. A line with up to 125 bus nodes can be connected via the PROFIBUS DP interface of a CPU. Maximum distance between the CC and last node on the line: 23 km (with fiber optic cable).

S7-400 communication

The SIMATIC S7-400 has different communication options:

• Combined multipoint interface and DP master, integrated into all CPUs:
  For the simultaneous connection of PGs/PCs, HMI systems, S7-200 and S7-300 systems and other S7-400 systems.
• Additional PROFIBUS DP interface, integrated into several CPUs for cost-effective connection of distributed I/O systems, e.g. ET 200.
• Integral PROFINET interface on PROFINET CPUs for connections to distributed I/O systems, or communication with other controllers and PC systems.
• Communications processors for connecting to the bus systems PROFIBUS und Industrial Ethernet.
• Communications processors for the powerful point-to-point connections.

Process communication via PROFIBUS DP

The SIMATIC S7-400 can be connected as master with PROFIBUS DP via the integral PROFIBUS DP interface of the S7-400-CPU (optional).

The following can be connected as masters on PROFIBUS DP:

• SIMATIC S7-400 (CPUs, CP 443-5)
• SIMATIC S7-300 (CPUs, CP 342-5 DP or CP 343-5)
• SIMATIC C7 (via C7 with PROFIBUS DP interface or PROFIBUS DP CPs)

Although PG/PCs with STEP 7 or OPs are masters on the bus, they only use the PG and OP functions that also run in part via PROFIBUS DP.

The following can be connected as slaves:

• Distributed I/O devices, e.g. ET 200
• Field devices
• SIMATIC S7-200, S7-300
• C7-633/P DP, C7-633 DP, C7-634/P DP, C7-634 DP, C7-626 DP
• SIMATIC S7-400 (via CP 443-5 only)

Data communication via multipoint interface (MPI)

The multipoint interface (MPI) is a communication interface integrated into the CPUs of the SIMATIC S7-400.

It is used for:

• Programming and parameterization
• HMI
• Establishing simple network topologies involving equal communication partners
• Variable connection options:
  The MPI enables simultaneous connection of up to 32 nodes:
  • PGs/PCs
  • HMI systems
  • S7-200 (as slave)
  • S7-300
  • S7-400
  • C7
• Internal communications bus (C bus);
  communications processors and function modules with C bus connection can be addressed via the MPI or DP interface of the CPU via the C bus of the S7-400. This enables direct access from the PG to the modules connected on the C bus. The C bus can be transferred to up to 6 expansion units via interface modules.
• Performance data of the MPI:
  • Up to 32 MPI nodes
  • Data transfer rate up to 12 Mbps
• Flexible mounting options:
  Field-proven components are used to establish MPI communication: Bus cable, bus connector and RS 485 repeater (12 Mbit/s) from the PROFIBUS and "distributed I/O" range.
  They enable optimal adaptation of the design to the requirements. For example, up to 9 repeaters can be switched in series to bridge larger distances between any two MPI nodes.
• DP master:
  The MPI of the S7-400 can also be configured as a DP master. Up to 32 DP slaves up to max. 12 Mbit/s can then be connected. The programming function and the human machine interface function are then retained

Data communication via CP (point-to-point)

Powerful point-to-point connections can be implemented via the CP 441 communications processors.

• Diverse connection options, including, for example:
  • PCs
  • SIMATIC S5/S7
  • Industrial PCs
  • PLCs from other manufacturers
  • Scanners, barcode readers, identification systems
  • Robot controls
  • Printers
• Variable interfaces:
  Replaceable interface modules enable communication using different transmission media:
  • 20 mA (TTY)
  • RS 232C (V.24)
  • RS 422/485

Data communication via CP (PROFIBUS or Industrial Ethernet)

The SIMATIC S7-400 can be connected to the PROFIBUS and Industrial Ethernet bus systems via the CP 443-x communications processors,

including, for example:

• SIMATIC S7-200 (via PROFIBUS)
• SIMATIC S7-300
• SIMATIC S7-400
• SIMATIC S5-115U/H, S5-135U, S5-155U/H
• Programming devices
• Personal computers
• SIMATIC HMI human machine interface systems
• Numerical controllers
• Robot controls
• Industrial PCs
• Drive controls
• Devices of other manufacturers

S7-400H

The SIMATIC S7-400H consists of the following components:

• 2 central controllers:
  Either 2 separate UR1/UR2 central controllers or 2 areas on one divided central controller (UR2-H).
• 2 sync modules per central controller for linking both devices via fiber optic cable.
• 1 CPU 412-5H, 1 CPU 414-5H, 1 CPU 416-5H or 1 CPU 417-5H per central controller.
• S7-400 I/O modules in the central controllers.
• UR1/UR2/ER1/ER2 expansion units and/or ET 200M distributed I/O devices with I/O modules.

Central functions are redundant in design. The I/O can be configured with normal availability and switched.

Normally available I/O (one-sided configuration)

In a one-sided configuration, I/O modules are single-channel in design and are addressed by only one of the two central controllers. One-sided I/O modules can be plugged into a central controller and/or into expansion units/distributed I/O devices.

Information read in on one side is always available to both central controllers provided the device addressing the I/O is working correctly. In the event of a fault, the I/O modules of the affected central controller are out of service.

One-sided configuration is used:

• For plant sections that do not require increased availability.
• For connecting user-program-based, redundant I/O. The system has to be set up symmetrically here.

Increased availability (switched configuration)

In a switched configuration, I/O modules are single-channel in design but they are addressed via a redundant PROFIBUS DP by both central controllers. I/O modules operated in a switched configuration can only be plugged into an ET 200M distributed I/O device.

Connection to the central controllers is made via PROFIBUS DP.

Redundancy of the I/O

Redundant I/O modules are configured redundantly in pairs. The use of redundant I/O offers maximum availability because in this way, the failure of a CPU, a PROFIBUS or a signal module is tolerated.

The following configurations are possible:

• Redundant I/O in single-sided DP slaves
• Redundant I/O in switched DP slaves

Suitable I/O modules

Mutually redundant modules must be of the same type and design (e.g. both centralized or both distributed). The slots are not stipulated. However, use in different stations is recommended for availability reasons. Please refer to Customer Support or the manual to see which modules can be used.

Redundancy of the FMs and CPs

Function modules (FMs) and communications processors (CPs) can be used redundantly in two different configurations:

• Switched redundant configuration:
  The FMs/CPs can be connected in duplicate to separate ET 200Ms or one switched ET 200M.
• Two-channel redundant configuration:
  FMs/CPs can be plugged into both subunits or into expansion units connected to the subunits (see one-sided configuration).

The redundancy of the modules is achieved in different ways here:

• Programming by the user:
  On the function modules and the the SIMATIC CPs, the redundancy function can generally be programmed by the user. The active module is determined and a possible fault is detected to initiate a switchover. The required program corresponds to the program for a single CPU with redundant FM/CP.
• Direct support from the operating system.
  In the case of SIMATIC NET-CP 443-1, the operating system supports the redundancy direct. For further details, see under Communication below.

S7-400F/FH

A fail-safe S7-400F/FH automation system can be configured differently according to requirements:

Single-channel, one-sided I/O for S7-400F

The plant requires a fail-safe controller. Fault tolerance is not required. The following are required:

• 1 CPU 414-4H/417-4H with F-Runtime license.
• 1 PROFIBUS DP line.
• ET 200M with IM 153-2.
• Fail-safe signal modules in non-redundant design.

In the event of a fault, the I/O is no longer available. The fail-safe signal modules are passivated.

Single-channel, switched I/O for S7-400FH

The plant requires a fail-safe controller. Fault tolerance is required on the CPU side. The following are required:

• 2 CPU 414-4H/417-4H with F-Runtime license.
• 2 PROFIBUS DP lines.
• 1 ET 200M with 2 IM 153-2 (redundant).
• Fail-safe signal modules in non-redundant design.

If the CPU, IM 153-2 or PROFIBUS DP line fails, the controller remains available. In the case of failure of the fail-safe signal modules or the ET 200M, the I/O is no longer available. The fail-safe signal modules are passivated.

Redundant, switched I/O for S7-400FH

The plant requires a fail-safe controller. Fault tolerance is required on the CPU side and the I/O side. The following are required:

• 2 CPU 414-4H/417-4H with F-Runtime license.
• 2 PROFIBUS DP lines.
• 2 ET 200M with 2 IM 153-2 (redundant).
• Fail-safe signal modules in redundant design.

In the event of failure of the CPU, IM 153-2 or PROFIBUS DP line, fail-safe signal modules or ET 200M, the controller remains available.

Standard modules can also be used in the S7-400F/FH automation system. These must not be used together with fail-safe modules in one ET 200M.

Communication

Safety-related and standard communication between the central controller and the ET 200M takes place via PROFIBUS DP. The specially developed PROFIBUS profile PROFIsafe allows the transmission of user data associated with the safety function within the standard data telegram. Additional hardware components such as special safety buses are not required. The necessary software is either integrated in the hardware components as an expansion of the operating system or loaded into the CPU later as a certified software block.

Safety class with isolation module

Use of the isolation module in the ET 200M offers the following benefits:

• PROFIBUS DP lines can be established with copper bus cables. The use of fiber optic cables is not necessary.
• Every IM 153-x can be used.
• Mixed operation of fail-safe signal modules in safety mode and S7-300 standard modules in one ET 200M is possible.

The isolation module is not required if safety class SIL 2 is to be achieved.