SIMATIC is a series of

programmable logic controller A programmable logic controller (PLC) or programmable controller is an industrial computer that has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, machines, robotic devices, or any activity tha ...

and automation systems, developed by

Siemens Siemens AG ( ) is a German multinational conglomerate corporation and the largest industrial manufacturing company in Europe headquartered in Munich with branch offices abroad. The principal divisions of the corporation are ''Industry'', '' ...

. Introduced in 1958, the series has gone through four major generations, the latest being the ''SIMATIC S7'' generation. The series is intended for industrial automation and production. The name ''SIMATIC'' is a registered trademark of Siemens. It is a

portmanteau A portmanteau word, or portmanteau (, ) is a blend of words As with other

s, SIMATIC devices are intended to separate the control of a machine from the machine's direct operation, in a more lightweight and versatile manner than controls hard-wired for a specific machine. Early SIMATIC devices were transistor-based, intended to replace relays attached and customized to a specific machine. Microprocessors were introduced in 1973, allowing programs similar to those on general-purpose digital computers to be stored and used for machine control. SIMATIC devices have input and output modules to connect with controlled machines. The programs on the SIMATIC devices respond in

real time Real-time or real time describes various operations in computing or other processes that must guarantee response times within a specified time (deadline), usually a relatively short time. A real-time process is generally one that happens in defined ...

to inputs from

sensor A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or changes in its environment and sends ...

s on the controlled machines, and send output signals to

actuator An actuator is a component of a machine that is responsible for moving and controlling a mechanism or system, for example by opening a valve. In simple terms, it is a "mover". An actuator requires a control device (controlled by control signal) a ...

s on the machines that direct their subsequent operation. Depending on the device and its connection modules, signals may be a simple binary value ("high" or "low") or more complex. More complex inputs, outputs, and calculations were also supported as the SIMATIC line developed. For example, the SIMATIC 505 could handle floating point quantities and trigonometric functions.

Product lines

Siemens has developed four product lines to date: * 1958: SIMATIC Version G * 1973: SIMATIC S3 * 1979: SIMATIC S5 * 1995: SIMATIC S7

SIMATIC S5

The S5 line was sold in 90U, 95U, 101U, 100U, 105, 110, 115,115U, 135U, and 155U chassis styles. Within each chassis style, several

CPU A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and ...

s were available, with varying speed, memory, and capabilities. Some systems provided redundant CPU operation for ultra-high-reliability control, as used in

pharmaceutical A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and re ...

manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to a r ...

, for example. Each chassis consisted of a

power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a r ...

, and a backplane with slots for the addition of various option boards. Available options included serial and Ethernet communications, digital input and output cards,

analog signal processing Analog signal processing is a type of signal processing conducted on continuous analog signals by some analog means (as opposed to the discrete digital signal processing where the signal processing is carried out by a digital process). "Analog" indi ...

boards, counter cards, and other specialized interface and function modules.

SIMATIC S7

The first entries in the S7 line were released in 1994, available under three performance classes: S7-200, S7-300 and S7-400. The introduction of SIMATIC S7 saw also the release of a new fieldbus standard Profibus, and the pioneer use of

industrial Ethernet Industrial Ethernet (IE) is the use of Ethernet in an industrial environment with protocols that provide determinism and real-time control. Protocols for industrial Ethernet include EtherCAT, EtherNet/IP, PROFINET, POWERLINK, SERCOS III, CC ...

to facilitate communication between automation devices. The great success of the S7-300 CPU family in particular helped to cement the role of Siemens as one of the global leaders in automation technology. These series are expected to be phased out in 2023. The first generation of S7 CPUs were later succeeded by the S7-1200 and S7-1500, released in 2012. These models came with standard Profinet interface.

Software

Programs running on SIMATIC devices run in software environments created by Siemens. The environment varies by product line: * The SIMATIC S5 product line is programmed in STEP 5. * The SIMATIC S7 product line is programmed in STEP 7 (V5.x or TIA Portal).

Step 5

The S5 product line was usually programmed with a PC based software programming tool called ''STEP 5''. STEP 5 was used for programming, testing, and commissioning, and for documentation of programs for S5 PLCs. The original STEP 5 versions ran on the

CP/M operating system CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...

. Later versions ran on

MS-DOS MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few ope ...

, and then versions of Windows through

Windows XP Windows XP is a major release of Microsoft's Windows NT operating system. It was released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Windows 2000 for high-end and ...

. The final version of STEP 5 was version 7.2 (upgradable to version 7.23 Hotfix 1 with patches). In addition to STEP 5, Siemens offered a proprietary State logic programming package called Graph5. Graph5 is a sequential

programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...

intended for use on machines that normally run through a series of discrete steps. It simulates a

State machine A finite-state machine (FSM) or finite-state automaton (FSA, plural: ''automata''), finite automaton, or simply a state machine, is a mathematical model of computation. It is an abstract machine that can be in exactly one of a finite number o ...

on the S5 platform. Several third-party programming environments were released for the S5. Most closely emulated STEP 5, some adding macros and other minor enhancements, others functioning drastically differently from STEP 5. One allowed STEP 5 programs to be cross-compiled to and from the C programming language and

BASIC BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...

Structured programming

STEP 5 allowed 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 A circuit diagram (wiring diagram, electrical diagram, elementary diagram, electronic schematic) is a graphical representation of an electrical circuit. A pictorial circuit diagram uses simple images of components, while a schematic diagram s ...

Function Block Diagram The Function Block Diagram (FBD) is a graphical language for programmable logic controller design, that can describe the function between input variables and output variables. A function is described as a set of elementary blocks. Input and out ...

(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 key A function key is a key on a computer or terminal keyboard that can be programmed so as to cause an operating system command interpreter or application program to perform certain actions, a form of soft key. On some keyboards/computers, function ...

s. They are displayed on the screen as graphical symbols. There are several program editors, from either genuine Siemens, or from other suppliers. After Siemens discontinued support, other suppliers started to develop new STEP 5 version which can run on Windows XP, or Windows 7.

Blocks

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.

Operations

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 An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...

) - These can only be executed in STL.

Stuxnet

The

Stuxnet Stuxnet is a malicious computer worm first uncovered in 2010 and thought to have been in development since at least 2005. Stuxnet targets supervisory control and data acquisition ( SCADA) systems and is believed to be responsible for causing su ...

computer worm A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. It often uses a computer network to spread itself, relying on security failures on the target computer to access it. It wil ...

specifically targets SIMATIC S7 PLCs via its STEP 7 programming environment.

References

External links

Official product page
* * * {{Authority control Digital electronics Embedded systems Industrial automation Control engineering Siemens products