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The Simatic S5 PLC is an automation system based on Programmable Logic Controllers. It was manufactured and sold by Siemens AG. Such automation systems control process equipment and machinery used in manufacturing. This product line is considered obsolete, as the manufacturer has since replaced it with their newer Simatic S7 PLC. However, the S5 PLC still has a huge installation base in factories around the world. Most automation systems integrators still have the ability to provide support for the platform.

S5-90/95U/F S5-100U S5-115U/H/F S5-135/155U/H/F S5-110A S5-130/150A/K/S S5


siemens spare parts /  Stop production close to 20 years

For over two decades, the SIMATIC S5 was successfully used in the process industry and in manufacturing automation as a complete controller family for awide range of controller tasks. Many SIMATIC S5 control systems are still in reliable service today, but rapid technological changes and increased market demands place stringent requirements on the automation system of today and tomorrow. A migration from SIMATIC S5 controllers to SIMATIC S7 is therefore always a wise decision. However, an upgrade to a DCS might perform better depending on your application. For these circumstances the “Totally Integrated Automation” (TIA) concept of Siemens offers a lot of interesting possibilities.


With discontinuation of the S5 product series, maintenance of these control system is becoming more difficult and

Simatic S5 Series

  • S5-90/95U/F
  • S5-100U
  • S5-115U/H/F
  • S5-135/H/F
  • S5-155U/H/F
  • S5-110A
  • S5-130A/K/S
  • S5-150A/K/S

expensive. This situation can be avoided by migrating to SIMATIC PCS 7. At the same time, you gain access to the latest process control system functions, thereby increasing the productivity of your plant significantly. A combination of SIMATIC PCS 7 and the SIMATIC S5 automation system can also be implemented as part of a Siemens migration. The combination of process control system and programmable logic controller is referred to as a hybrid application. When hybrid applications are used, it should be ensured that the process control system used combines the best properties of both systems on one platform and assures common communication. Based on its many years of experience in manufacturing and installation of PLCs and full-blown process control systems, Siemens is your qualified partner in the optimized transition from your SIMATIC S5 controller to the SIMATIC PCS 7

process control system.

Based on our many years of experience in migrating a variety of automation and process control systems, we have developed the following opportunities for SIMATIC S5 controllers:

  •     System expansion with SIMATIC PCS 7
  •     Migration of S5 controller while retaining the S5 I/O modules
  •     Complete replacement while retaining the field cables


For system expansions with SIMATIC PCS 7, the existing SIMATIC S5 system architecture is extended, i.e., the S5 operator panel or SCADA system is retained and operates in parallel with the HMI of the connected SIMATIC PCS 7 architecture. The SIMATIC S5 PLCs are connected to the SIMATIC PCS 7 controllers as slaves, which expands the available functions of the existing automation system to include alarm management, asset management, and even graphical visualization. The existing process I/O are retained in this case.

In a migration of SIMATIC S5 controllers with retention of the S5 input/output modules, the existing SIMATIC S5 CPUs are replaced with modern SIMATIC S7-400 CPUs. The S5 ET 200U input/output modules can be connected directly to the new system via PROFIBUS DP. The IM 463-2 interface module can be used to establish a connection between a modern S7-400 controller and other S5 input/output modules.

Comprehensive modernization is often forced by the shortage of spare parts for the old system, lack of support, and the need for additional functions, for instance, for fieldbus technology or IT integration. In this case, it is worthwhile to completely replace the existing SIMATIC S5 control system with the modern SIMATIC PCS 7 process control system. With this modernization solution, we enable a step-wise, tool-supported system analysis and conversion of the SIMATIC S5 controllers and input/output modules to modern ET 200M and SIMATIC S7-400 modules, which communicate directly with the higher-level SIMATIC PCS 7 server-client architecture. Existing wiring can be retained through the use of our I/O adapter. Thus, the considerable effort for new loop checks is unnecessary and even signal checks can be largely eliminated, because the signals are reconfigured in the software by means of an assignment list.

Advantages of migration to SIMATIC PCS 7
The migration of an old system to SIMATIC PCS 7 pays off many times over: It assures the continuity of process control system investments, makes the systems more efficient and productive, and extends the system service life in a cost-effective manner.

Additional winning advantages:

  •     Step-wise or complete system modernization
  •     Future viability assured due to use of a modern and flexible process control system
  •     Modern technology reduces the risk of plant outages
  •     Increased productivity due to higher availability of the new process control system
  •     Reduced costs for stocking spare parts and for maintenance
  •     Investment protection based on the Totally Integrated Automation (TIA) concept
  •     Use of SIMATIC PCS 7 reveals potential for process optimization, thus increasing production output
  •     Resource optimization and quality improvement due to increased information density and quality
  •     SIMATIC PCS 7 establishes the basis for connection to a Manufacturing Execution System (MES)

The Simatic S5 PLC is an automation system based on Programmable Logic Controllers. It is manufactured and sold by Siemens AG. Such automation systems control process equipment and machinery used in manufacturing. This product line is considered obsolete, as the manufacturer has since replaced it with their newer Simatic S7 PLC. However, the S5 PLC still has a huge installation base in factories around the world. Most automation systems integrators still have the ability to provide support for the platform.

Simatic S5 Hardware

The S5 line comes in the 90U, 95U,101U,100U, 105, 115U, 135U, and 155U chassis styles.Higher the number, the more sophisticated and more expensive the system. Within each chassis style, several CPUs are available, with varying speed, memory, and capabilities. Some systems provide redundant CPU operation for ultra-high-reliability control, as used in pharmaceutical manufacturing, for example.

Each chassis consists of a power supply, and a backplane with slots for the addition of various option boards. Available options include serial and Ethernet communications, digital input and output cards, analog signal processing boards, counter cards, and other specialized interface and function modules.

Simatic S5 Software

The S5 product line is usually programmed with a PC based software programming tool called Step 5. Step 5 is used for programming, testing, and commissioning, and for documentation of programs for S5 PLCs.

The original Step 5 versions ran on the CPM operating system. Later versions ran on MS-DOS, and then versions of Windows through Windows XP. The final version of Step 5 is version 7.2. No further development of this product line has occurred since that time, due to its announced obsolescence.

In addition to Step5, Siemens offered a proprietary State logic programming package called Graph5. Graph5 is a sequential programming language intended for use on machines that normally run through a series of discrete steps. It simulates a State machine on the S5 platform.

Several third-party programming environments have been released for the S5. Most closely emulate Step5, some adding macros and other minor enhancements, others functioning drastically differently than Step5. One allows Step5 programs to be cross-compiled to and from the C programming language and BASIC.

Structured programming

STEP 5 allows the creation of structured or unstructured programming, from simple AND/OR operations up to complex subroutines. A STEP 5 program may, therefore, contain thousands of statements.

To maintain maximum transparency, STEP 5 offers a number of structuring facilities:

  • Block technique – A linear operation sequence is divided into sections and packed into individual blocks.
  • Segments – Within blocks, fine structuring is possible by programming subtasks in individual segments.
  • Comments – Both a complete program as well as individual blocks or segments and individual statements can be directly provided with comments.

Methods of representation

STEP 5 programs can be represented in three different ways:

  • Statement List (STL) – The program consists of a sequence of mnemonic codes of the commands executed one after another by the PLC.
  • Ladder Diagram (LAD) – Graphical representation of the automation task with symbols of the circuit diagram
  • Function Block Diagram (FBD) – Graphical representation of the automation task with symbols to DIN 40700/ DIN 40719.

Absolute or symbolic designations can be used for operands with all three methods of representation.

In LAD and FBD complex functions and function block calls can be entered via function keys. They are displayed on the screen as graphical symbols.


Five types of blocks are available:

  • Organization blocks (OB) – for managing the control program
  • Programming blocks (PB) – contain the control program structured according to functional or process-oriented characteristics
  • Sequence blocks (SB) – for programming sequential controls
  • Function blocks (FB) – contain frequently occurring and particularly complex program parts
  • Data blocks (DB) – for storing data required for processing the control program.

Some S5 PLCs also have block types FX (Extended Function Blocks), and DX(Extended Data Blocks); these are not distinct block types, but rather are another set of available blocks due to the CPU having more memory and addressing space.


STEP 5 differentiates between three types of operations:

  • Basic operations, (e.g. linking, saving, loading & transferring, counting, comparing, arithmetic operations, module operations) – These can be performed in all three representations.
  • Supplementary operations and complex functions, (e.g. substitution statements, testing functions, word-by-word logic operations, decrement/increment and jump functions.) – These can only be executed in STL.
  • System operations (direct access the operating system) – These can only be executed in STL.

Additional functions

  • Saving user-specific project settings
  • Symbol editor
  • Automatic generation and updating of cross-reference lists
  • Comparison of user programs
  • Transferring blocks to EPROM and EEPROM memory modules for programmable controllers
  • Rewiring inputs, outputs, flags, timers and counters
  • Testing and service functions for startup and maintenance
  • S5-095U and S5-100U
  • S5-110
  • S5-115
  • S5-130 and S5-150
  • S5-130 and S5-150
  • S5 Operator Panels
  • S5-135 and S5-155
  • S5 Programming
  • S5 Batteries

More Version on Siemens S5 PLC




Siemens Simatic S5 6ES5451-4UA11 Output Module

Article Number (Market Facing Number) 6ES5451-4UA11
Product family Not available
Product Lifecycle (PLM) PM500:Discontinued Product or end of PLM & Support
PLM Effective Date End of product lifecycle since: 01.04.1999
Product is no longer available. Successor:6ES5451-4UA14
Successor information
Successor 6ES5451-4UA14
Successor Description ***Spare part*** SIMATIC S5,Digitaloutput 451-4 Isolated Compact design 32 ouputs 24 V DC/0.5 A
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LKZ_FDB/ CatalogID ST9-E5
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WEEE (2012/19/EU) Take-Back Obligation
REACH Art. 33 Duty to inform according to the current list of candidates