Configuring Hardware and Communication Connections STEP 7 Manual, 04/2017, A5E41639776-AA 3 Preface Purpose This manual provides a complete overview of programming with STEP 7. A channel is the PROFINET IO term which refers to one physical discrete input, discrete output, analog input or analog output. A device can have almost any number of slots, subslots and channels. Except for Slot zero, every other slot and subslot contains status, diagnostic and alarm data for the channels of that slot.
- At the heart of any computer system are the numbering systems and digital codes used for instructions and memory storage. Besides the ones and zeros it is important to understand how these bits are packaged into codes like BCD and Gray codes. Understanding these concepts enables the programmer to manipulate the PLC at it's most basic level.
- Introduction Siemens makes several PLC product lines in the SIMATIC S7 family. They are: S7-200, S7-300, and S7-400. Siemens Step 7 is a powerful integrated software solution for automation, and includes the programming environment for Siemens programmable logic controllers (PLCs). This software provides unique and powerful programming tools with multiple benefits.
- S7-plc-exporter - a Prometheus exporter for Siemens S7 PLC. S7-plc-exporter is a generic Prometheus exporter for values from Siemens S7 PLC (See sompatibilty) Prerequisites. In order to run s7-plc-exporter you need Node.js installed on your system. The Installation is simple as can be. Npm i Configuration.
Nowadays, multiple companies are manufacturing and designing the programmable logic controller (PLC) software as well as hardware devices.
In an earlier article, we have seen topmost PLC brands and their useful software. Here, we are going to study PLC rack of the hardware devices which are mostly used in the industrial environment.
Generally, Fixed PLC and Modular PLC types of PLC are constructed. But, modular PLC is mostly used in the industrial environment.
Sometimes, modular PLC is known as Rack-mounted PLC because, both are having the same functions.
Let's starts from the basics of rack and chassis of PLC.
What is PLC Rack?
PLC rack and chassis are mostly used in the Modular PLC or Rack Mounted PLC hardware.
Rack and chassis acts as a backbone of the PLC hardware system. It is helpful for assembling the modular PLC hardware modules.
Definition of PLC Rack:
PLC rack or chassis is a hardware assembly that plugs communicating modules together (like input, output, CPU, power supply, communication, and additional function modules) in a single frame.
If you look at the below PLC designing structure, it looks more like a rack or chassis.
From the above diagram, you can see the multiple input or output modules that are plugged together in the same rack or chassis of modular PLC.
In the PLC rack, the power supply module provides the required level of the regulated power to the different input-output modules through the backplane bus system.
Rack Mounted or Modular PLC Block Diagram
There is a standard card where all the modules gets deployed to communicate through the rack.
With the help of rack and chassis, modules can be easily communicated to the other connected modules in the PLC system.
What are the types of Rack used in Modular PLC?
The modular PLC rack provides power and interconnectivity between multiple connected modules through the backplane.
Based on the backplane, rack are classified into different parts.
- Active Backplane
- Passive Backplane
1. Active Backplane
Active backplane consists of multiple slots and additional circuitry. It can easily control all communication between the slots.
Active backplane is mostly used in the Siemens (S7-400) PLC. Siemens (S7-400) PLC module can be placed into three different types of the rack.
- Central Rack (CR)
- Universal Rack (UR)
- Expansion Rack (ER)
These three main types of PLC rack are used in the modular PLC or Rack mounted PLC.
2. Passive Backplane
Passive backplane consists of only slots. This is no additional circuit. It is mostly used in the Siemens (S7-300) PLC.
What are the difference between Rack and Chassis of PLC?
PLC Rack and chassis has little difference. Otherwise, both are doing the same work.
Let's see the main difference between the rack and chassis of PLC.
- PLC Rack:
The rack of PLC is a hardware device that holds together communicating modules in a single frame.
Rack is cabinet for placing the modules. It comes in a different sizes like 9 slots,18 slots, etc.
- PLC Chassis:
The chassis of PLC is a piece of hardware which has multiple slots for inserting the different or additional modules.
In the PLC system, there are different slots for chassis available. If the user wants additional chassis, we can connect them by using chassis interconnecting cables.
What is the Purpose of Rack or Chassis in PLC?
PLC rack and chassis has multiple functions to use.
- Rack or chassis distributes power in the PLC.
- It provides interconnectivity between connecting I/O PLC modules.
- In rack-mounted PLC, we can easily modify or expand input and output modules.
- It acts as a communication link between communicating modules.
- In any fault condition, we can easily remove and replace the individual module through PLC rack or chassis.
Hope you understand the difference between the rack and chassis of plc with the help of a circuit diagram of the rack-mounted PLC systems.
Interested to learn about software-based PLC programming? I have a curated tutorial on ‘[Step-by-Step] How to Learn PLC Programming at Home for Free?‘.
If you have any quires, you can freely ask with me by commenting below. If you find this tutorial helpful, kindly share it.
Happy PLC Learning!
I have completed master in Electrical Power System. I work and write technical tutorials on the PLC, MATLAB programming, and Electrical on DipsLab.com portal.
Sharing my knowledge on this blog makes me happy. And sometimes I delve in Python programming.
SIMATIC is a series of programmable logic controller and automation systems, developed by Siemens. 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 of 'Siemens' and 'Automatic'.
Function[edit]
As with other programmable logic controllers,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 programssimilar to those on general-purpose digital computers to be stored and used for machine control.[1] SIMATIC devices have input and output modules to connect with controlled machines. The programs on the SIMATIC devices respond in real time to inputs from sensors on the controlled machines, and send output signals to actuators on the machines that direct their subsequent operation.
Siemens Plc Slot Numbering Software
Depending on the device and its connection modules, signals may be a simple binary value ('high' or 'low') or more complex. For example, a binary input going from a thermometer on a machine to a SIMATIC device might have the following meanings:
- 'High' signal: Temperature exceeded an operating limit
- 'Low' signal: Temperature is within expected limits
Based on this input, and other factors, the program on the SIMATIC device might send a binary output signal to the same machine with the following meanings:
- 'High' signal: Run the motor
- 'Low' signal: Stop the motor
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.[2]
Product lines[edit]
Siemens has developed four product lines to date:
PLC rack and chassis are mostly used in the Modular PLC or Rack Mounted PLC hardware.
Rack and chassis acts as a backbone of the PLC hardware system. It is helpful for assembling the modular PLC hardware modules.
Definition of PLC Rack:
PLC rack or chassis is a hardware assembly that plugs communicating modules together (like input, output, CPU, power supply, communication, and additional function modules) in a single frame.
If you look at the below PLC designing structure, it looks more like a rack or chassis.
From the above diagram, you can see the multiple input or output modules that are plugged together in the same rack or chassis of modular PLC.
In the PLC rack, the power supply module provides the required level of the regulated power to the different input-output modules through the backplane bus system.
Rack Mounted or Modular PLC Block Diagram
There is a standard card where all the modules gets deployed to communicate through the rack.
With the help of rack and chassis, modules can be easily communicated to the other connected modules in the PLC system.
What are the types of Rack used in Modular PLC?
The modular PLC rack provides power and interconnectivity between multiple connected modules through the backplane.
Based on the backplane, rack are classified into different parts.
- Active Backplane
- Passive Backplane
1. Active Backplane
Active backplane consists of multiple slots and additional circuitry. It can easily control all communication between the slots.
Active backplane is mostly used in the Siemens (S7-400) PLC. Siemens (S7-400) PLC module can be placed into three different types of the rack.
- Central Rack (CR)
- Universal Rack (UR)
- Expansion Rack (ER)
These three main types of PLC rack are used in the modular PLC or Rack mounted PLC.
2. Passive Backplane
Passive backplane consists of only slots. This is no additional circuit. It is mostly used in the Siemens (S7-300) PLC.
What are the difference between Rack and Chassis of PLC?
PLC Rack and chassis has little difference. Otherwise, both are doing the same work.
Let's see the main difference between the rack and chassis of PLC.
- PLC Rack:
The rack of PLC is a hardware device that holds together communicating modules in a single frame.
Rack is cabinet for placing the modules. It comes in a different sizes like 9 slots,18 slots, etc.
- PLC Chassis:
The chassis of PLC is a piece of hardware which has multiple slots for inserting the different or additional modules.
In the PLC system, there are different slots for chassis available. If the user wants additional chassis, we can connect them by using chassis interconnecting cables.
What is the Purpose of Rack or Chassis in PLC?
PLC rack and chassis has multiple functions to use.
- Rack or chassis distributes power in the PLC.
- It provides interconnectivity between connecting I/O PLC modules.
- In rack-mounted PLC, we can easily modify or expand input and output modules.
- It acts as a communication link between communicating modules.
- In any fault condition, we can easily remove and replace the individual module through PLC rack or chassis.
Hope you understand the difference between the rack and chassis of plc with the help of a circuit diagram of the rack-mounted PLC systems.
Interested to learn about software-based PLC programming? I have a curated tutorial on ‘[Step-by-Step] How to Learn PLC Programming at Home for Free?‘.
If you have any quires, you can freely ask with me by commenting below. If you find this tutorial helpful, kindly share it.
Happy PLC Learning!
I have completed master in Electrical Power System. I work and write technical tutorials on the PLC, MATLAB programming, and Electrical on DipsLab.com portal.
Sharing my knowledge on this blog makes me happy. And sometimes I delve in Python programming.
SIMATIC is a series of programmable logic controller and automation systems, developed by Siemens. 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 of 'Siemens' and 'Automatic'.
Function[edit]
As with other programmable logic controllers,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 programssimilar to those on general-purpose digital computers to be stored and used for machine control.[1] SIMATIC devices have input and output modules to connect with controlled machines. The programs on the SIMATIC devices respond in real time to inputs from sensors on the controlled machines, and send output signals to actuators on the machines that direct their subsequent operation.
Siemens Plc Slot Numbering Software
Depending on the device and its connection modules, signals may be a simple binary value ('high' or 'low') or more complex. For example, a binary input going from a thermometer on a machine to a SIMATIC device might have the following meanings:
- 'High' signal: Temperature exceeded an operating limit
- 'Low' signal: Temperature is within expected limits
Based on this input, and other factors, the program on the SIMATIC device might send a binary output signal to the same machine with the following meanings:
- 'High' signal: Run the motor
- 'Low' signal: Stop the motor
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.[2]
Product lines[edit]
Siemens has developed four product lines to date:
- 1958: SIMATIC Version G
- 1973: SIMATIC S3
- 1979: SIMATIC S5
- 1995: SIMATIC S7
SIMATIC S5[edit]
The S5 line was sold in 90U, 95U, 101U, 100U, 105, 110, 115,115U, 135U, and 155U chassis styles. The higher the number (except for the 101U), the more sophisticated and more expensive the system was. Within each chassis style, several CPUs were available, with varying speed, memory, and capabilities. Some systems provided redundant CPU operation for ultra-high-reliability control, as used in pharmaceuticalmanufacturing, for example.
Each chassis consisted of a power supply, 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 boards, counter cards, and other specialized interface and function modules.
SIMATIC S7[edit]
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 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 leader in automation technology. These series are expected to be phased out in 2023.[3]
The first generation of S7 CPUs were later succeeded by the S7-1200 and S7-1500, released in 2012.[4] These models came with standard Profinet interface.
Software[edit]
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).[5]
Step 5[edit]
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. Later versions ran on MS-DOS, and then versions of Windows through Windows XP. 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 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 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.
Structured programming[edit]
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.
Siemens Plc Slot Numbering Tool
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[edit]
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.
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[edit]
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[edit]
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.
Stuxnet[edit]
The Stuxnetcomputer worm specifically targets SIMATIC S7 PLCs via its STEP 7 programming environment.
References[edit]
- ^'60 Years of Simatic'. Siemens. Siemens. Retrieved 4 March 2020.
- ^'Siemens Simatic 505'. Computing History. Centre for Computing History. Retrieved 4 March 2020.
- ^'SIMATIC S7-300'. Siemens. Retrieved 12 November 2020.
- ^'What are the differences between SIMATIC S7-300 and S7-1500 PLCs?'. RealPars. Retrieved 12 November 2020.
- ^'PLC Programming with SIMATIC STEP'. Siemens. Siemens. Retrieved 4 March 2020.
External links[edit]
- Hans Berger (2009) [2000]. Automating with SIMATIC. ISBN978-3-89578-333-3.
- Hans Berger (2011). Automating with SIMATIC S7-1200. ISBN978-3-89578-356-2.
- Jürgen Müller (2005). Controlling with SIMATIC. ISBN978-3-89578-255-8.
