Detailed introduction of Siemens S7-300 series PLC

Overview

S7-300

• Modular micro PLC system, meeting performance requirements for medium and small-scale applications
• Various performance modules can effectively meet and adapt to automation control tasks
• Simple and practical distributed structure and multi interface network capability, with highly flexible applications
• Easy to operate, simple design, no fan included
• Can be smoothly expanded when tasks are added
• A large number of integrated functions make it very powerful

S7-300F

• Fault safe automation system that can meet the increasing safety requirements of factories
• Based on S7-300
• Can connect additional ET 200S and ET 200M distributed I/O stations equipped with safety modules
• Using PROFIBUS DP with PROFIsafe specifications for safety related communication
• Standard modules can also be used for non safety related applications

usability

The SIMATIC S7-300/ET 200M system family is a component of Siemens' existing product line and will generally be supplied until 2023.
According to the product elimination statement, these products will be supplied as spare parts for an additional 10 years.

Application

S7-300

SIMATIC S7-300 is a small PLC system suitable for the mid to low performance range.

Modular, fanless design, easy implementation of distributed structure, and convenient operation make SIMATIC S7-300 an economical and user-friendly solution for various tasks in mid to low-end applications.

The application areas of SIMATIC S7-300 include:

• Special Machinery
• textile machinery
• packaging machinery
• Manufacturing of general mechanical equipment
• Controller manufacturing
• Machine tool manufacturing
• Install the system
• Electrical and electronic industry and related industries

Multiple performance levels of CPUs, a full range of user-friendly modules that allow users to select corresponding modules according to different applications. When expanding tasks, the controller can be upgraded at any time by using additional modules.

SIMATIC S7-300 can be used universally:

• It has high electromagnetic compatibility, impact resistance, and vibration resistance, therefore it has * industrial applicability.

S7-300F

The SIMATIC S7-300F fail safe automation system can be used in equipment with high safety requirements. It can control processes that immediately shut down without posing a danger to personnel or the environment.

S7-300F meets the following safety requirements:

• Requirement levels AK 1 to AK 6, according to DIN V 1925/DIN V VDE 0801
• Safety requirement levels SIL 1 to SIL 3, according to IEC 61508
• Cat1 to Cat4, according to EN 954-1

In addition, standard modules can also be used together with fail safe modules in S7-300F. Therefore, it can create a fully integrated control system for use in factories where non safety related and safety related tasks coexist. The same standard tools can be used to configure and program the entire factory.

design

S7-300

Overview

The S7-300 automation system adopts modular design. It has a rich set of modules that can be combined in various ways.

The system includes the following components:

• A CPU:
  Different CPUs can be used for different performance ranges, including CPUs with integrated I/O and corresponding functions, as well as CPUs with integrated PROFIBUS DP, PROFINET, and point-to-point interfaces.
• Signal module (SM) for digital and analog input/output.
• A communication processor (CP) used to connect buses and point-to-point connections.
• Functional module (FM) for high-speed counting, positioning (open-loop/closed-loop), and PID control.

According to specific requirements, the following modules can also be used:

• The load power supply (PS) is used to connect the SIMATIC S7-300 to a 120/230 V AC power supply voltage.
• The interface module (IM) is used to connect the central controller (CC) and expansion unit (EU) in a multi-layer configuration.
  The SIMATIC S7-300 can operate through multiple 32 modules distributed across CC and 3 EU. All modules operate within the casing and do not require a fan.
• SIPLUS module suitable for expanding environmental conditions:
  Suitable for temperature range of -25 to+60 ° C, high humidity, condensation and frosting load conditions. It is resistant to direct sunlight, rain, or water splashes. When used in a cabinet with a protection level of IP20, it can be directly used in cars or outdoor buildings. Cabinets and IP65 enclosures that do not require air conditioning.

design

The simple design of S7-300 makes it versatile and easy to maintain:

• Installation module:
  Simply hang the module on the installation rail, rotate it into place, and then tighten the screws.
• Integrated Backplane Bus:
  Integrated backplane bus; The backplane bus is integrated onto the module. The modules are connected through a bus connector, which is inserted into the back of the housing.
• The module adopts mechanical coding, making it extremely easy to replace:
  When replacing a module, the fixing screws of the module must be unscrewed. Press the locking mechanism to easily remove the front connector. The encoding device on the front connector prevents misconnection of the wired connector to other modules.
• On site proven reliable connection:
  For signal modules, screw type, spring type, or insulation piercing type front connectors can be used.
• TOP Connection:
  Provide pre assembled wiring for the 1-wire to 3-wire connection system using screw type or spring type terminal blocks, and also allow direct wiring on the signal module.
• Required installation depth:
  All connections and connectors are located in the grooves on the module and are protected by a front cover. Therefore, all modules should have a clear installation depth.
• No slot rule:
  The signal module and communication processor can be connected in any way without restriction. The system can be configured by itself.

Expansion

If users need to use more than 8 slots to install signal modules, functional modules, or communication processor modules in their automation tasks, the S7-300 (excluding CPU 312 and CPU 312C) can be extended:

• The central controller and 3 expansion racks can connect up to 32 modules:
  A total of 3 expansion devices (EU) can be connected to the central controller (CC). Each CC/EU can connect eight modules.
• Connect through interface template:
  Each CC/EU has its own interface module. It is always plugged into the slot next to the CPU on the central controller and automatically processes communication with the expansion device.
  • Expand through IM 365:
    One expansion device extends a distance of 1 meter; The power supply voltage is also provided through an expansion device.
  • Expand through IM 360/361:
    Three expansion devices, with a distance of 10m between CC and EU, as well as between EU and EU.
• Physical isolation installation:
  For individual CC/EU, it can also be installed at a greater distance. Distance between two adjacent CC/EU or EU/EU: up to 10 meters
• Flexible installation options:
  CC/EU can be installed horizontally or vertically. This can maximize the satisfaction of space requirements.

Communication

S7-300 has different communication interfaces:

• A communication processor that connects AS Interface, PROFIBUS, and PROFINET/Industrial Ethernet bus systems.
• A communication module used for point-to-point connections.
• Multi point interface (MPI), integrated into the CPU;
  A low-cost solution for simultaneously connecting programmers/PCs, HMI systems, and other SIMATIC S7/C7 automation systems.

Process communication via PROFIBUS DP

The SIMATIC S7-300 is connected to the PROFIBUS DP bus system through a communication module or a CPU equipped with an integrated PROFIBUS DP interface. By using a CPU with PROFIBUS DP master/slave interface, a high-speed distributed automation system can be constructed, greatly simplifying operations.

From the user's perspective, distributed I/O processing on PROFIBUS DP is no different from centralized I/O processing (with the same configuration, addressing, and programming).

The following devices can be connected as the main station:

• SIMATIC S7-300
  (Use CPU with PROFIBUS DP interface or PROFIBUS DP CP)
• SIMATIC S7-400
  (Use CPU with PROFIBUS DP interface or PROFIBUS DP CP)
• SIMATIC C7
  (via C7 with PROFIBUS DP interface or via PROFIBUS DP CP)
• SIMATIC S5-115U/H, S5-135U, and S5-155U/H with IM 308
• SIMATIC 505

For performance reasons, the number of main stations connected on each line shall not exceed 2.

The following devices can be used as slave connections:

• ET 200 distributed I/O device
• S7-300， Through CP 342-5
• CPU 313C-2 DP，CPU 314C-2 DP，CPU 314C-2 PN/DP，CPU 315-2 DP，CPU 315-2 PN/DP，CPU 317-2 DP，CPU 317-2 PN/DP 和 CPU 319-3 PN/DP
• C7-633/P DP，C7-633 DP，C7-634/P DP，C7-634 DP，C7-626 DP，C7-635，C7-636
• field equipment

Although the programmer/PC or OP with STEP 7 is the main station on the bus, it only uses MPI function, and partially provides OP function through PROFIBUS DP.

Process communication through PROFINET IO

The SIMATIC S7-300 is connected to the PROFINET IO bus system through a communication module or a CPU equipped with an integrated PROFINET interface. By using a CPU with a PROFIBUS interface, a high-speed distributed automation system can be constructed, greatly simplifying operations.

From the user's perspective, distributed I/O processing on PROFINET IO is no different from centralized I/O processing (with the same configuration, addressing, and programming).

The following devices can be connected as IO controllers:

• SIMATIC S7-300
  (Using a CPU equipped with PROFINET interface or PROFINET CP)
• SIMATIC ET 200
  (via CPU with PROFINET interface)
• SIMATIC S7-400
  (Using a CPU equipped with PROFINET interface or PROFINET CP)

The following devices can be connected as IO devices:

• ET 200 distributed I/O device
• ET 200S IM151-8 PN/DP CPU, ET 200pro IM154-8 PN/DP CPU
• SIMATIC S7-300
  (Using a CPU equipped with PROFINET interface or PROFINET CP)
• field equipment

Process communication through AS Interface

The S7-300 has a communication module (CP 342-2) suitable for connecting field devices (AS Interface slaves) to the AS Interface bus.

For more information, please refer to Communication Processor.

Data communication through CP or integrated interface (point-to-point)

Through the integrated interface of CP 340/CP 341 communication processor or CPU 313C-2 PtP or CPU 314C-2 PtP, point-to-point connections can be established cost effectively. There are three physical transmission media that support different communication protocols:

• 20 mA (TTY) (CP 340/CP 341 only)
• RS 232C/V.24（仅 CP 340/CP 341）
• RS 422/RS 485

Can connect to the following devices:

• SIMATIC S7, SIMATIC S5 automation systems and systems from other companies
• printer
• Mechanical arm control device
• Scanners, barcode readers, etc

Special function blocks are included in the supply scope of the communication function manual.

Implementing data communication through Multi Point Interface (MPI)

MPI (Multipoint Interface) is a communication interface integrated into SIMATIC S7-300-CPU. Can be used for simple networking.

• MPI can simultaneously connect multiple programmers/PCs, HMI systems (OP/OS), S7-300, and S7-400 equipped with STEP 7.
• Global data:
  The 'Global Data Communication' service can periodically exchange data between networked CPUs. A S7-300 CPU can exchange data with up to 4 packets, each containing 22 bytes of data, and 16 CPUs can participate in data exchange simultaneously (using STEP 7 V4. x).
  For example, one CPU can access the input/output of another CPU. Global data communication can only be conducted through the MPI interface.
• Internal communication bus (C bus):
  The MPI of the CPU is directly connected to the C bus of S7-300. In this way, through MPI, FM/CP modules with C-bus interfaces can be directly addressed from the programmer.
• Communication technology for function *:
  • Up to 32 MPI nodes.
  • Each CPU using SIMATIC S7-300/-400 for S7 basic communication has multiple communication interfaces.
  • Each CPU that uses programmer/PC, SIMATIC HMI system, and SIMATIC S7-300/400 S7 communication has multiple communication interfaces.
  • Data transmission rate of 187.5 kbit/s or 12 Mbit/s
• Flexible configuration options:
  Establish MPI communication using reliable components: PROFIBUS and "distributed I/O" series bus cables, bus connectors, and RS 485 repeaters. By using these components, design adjustments can be made according to requirements. For example, any two MPI nodes can be cascaded with up to 10 relays to connect over larger distances.

Data communication through CP

The SIMATIC S7-300 can be connected to PROFIBUS and industrial Ethernet bus systems through CP 342 and CP 343 communication modules.

Can connect to the following devices:

• SIMATIC S7-300
• SIMATIC S7-400
• SIMATIC S5-115U/H、S5-135U、S5-155U/H
• Programming equipment
• PC
• SIMATIC HMI Human Machine Interface System
• CNC (Computer Numerical Control)
• Mechanical arm control device
• Industrial PC
• Drive control device
• Equipment from other manufacturers

S7-300F

The S7-300F can operate in two I/O designs:

• I/O Design in ET 200M:
  Fault safety digital/analog input and output modules for centralized or distributed applications (Cat.4/SIL3 can only be used with isolation modules)
• I/O Design in ET 200S PROFIsafe:
  Fault safety digital input and output modules can be used for distributed applications

function

S7-300

Provides a wide range of functions to support users in programming, debugging, and maintenance of S7-300.

• High speed instruction processing:
  The instruction execution time starts from 4 ns, opening up a new application in the mid to low performance range.
• Floating point operation:
  It can efficiently use floating-point and even complex arithmetic functions.
• User friendly parameter allocation:
  Only a software tool with a unified operating interface is needed to complete the parameterization of all modules. This reduces the entry threshold and training costs.
• Operator Control and Monitoring (HMI):
  User friendly HMI services have been integrated into the S7-300 operating system. These features no longer require expensive programming work: the SIMATIC HMI system requests process data from the SIMATIC S7-300, and the S7-300 operating system completes the automatic transmission of this data at the expected update time. And use the same symbols and database.
• Diagnostic function:
  The intelligent diagnostic system of the CPU continuously checks the system's functionality, records error messages, and specific system events (such as time errors, module failures, etc.). These events have been time tagged and stored in a circular buffer for future troubleshooting.
• Password protection:
  Use password protection function to reliably protect user information from unauthorized copying and alteration.

SIMATIC S7-300 complies with the following domestic and standards:

• CE Certification
• UL certification
• CSA certification
• CULus certification
• CULus HAZ.LOC certification
• FM certification
• ATEX certification
• Australian logo
• IEC 61131
• Classification Society Certification
  • ABS (American Bureau of Shipping)
  • BV (French Classification Society)
  • DNV (Norwegian Classification Society)
  • GL (Germanischer Lloyd)
  • LRS (Lloyd's Register of Shipping)
  • Class NK (Japan Classification Society)

For detailed information, please refer to the general technical data/1.1 standards and certifications in the manual "SIMATIC S7-300 Programmable Controller S7-300 Module Data".

Communication

SIMATIC S7-300-CPU supports the following communication types:

• Process communication:
  Loop addressing (swapping process images) of I/O modules through buses (AS Interface, PROFIBUS DP, or PROFINET). Call procedure communication from the loop execution layer.
• Data communication:
  Exchange data between automation systems or between HMI and multiple automation systems. Data communication can be looped or called from user programs through blocks when specific events occur.

The interface of STEP 7 is extremely user-friendly, significantly simplifying the user's communication function configuration work.

data communication

SIMATIC S7-300 supports different data communication mechanisms:

• Using MPI to achieve cyclic exchange of data packets between networked CPUs through global data communication.
• Utilize communication functions to achieve event driven communication with other partners. Realize network connection through MPI, PROFIBUS, or PROFINET.

Global data

By using the "Global Data Communication" service, networked CPUs can cyclically exchange data with each other (8 additional GD packets, each containing 22 bytes). Based on this, it can be achieved, for example, for one CPU to access information such as data, bit storage units, and process images from another CPU. Global data exchange can only be performed through MPI. The configuration is completed through the GD table in STEP 7.

Communication function

Through the integrated blocks within the system, communication services can be established with S7/C7 partners.

These services include:

• Perform S7 basic communication through MPI.
• S7 communication via MPI, C-bus, PROFIBUS, and PROFINET/Industrial Ethernet.
  You can use S7-300:
  • When used as a server, use MPI, C-bus, and PROFIBUS
  • As a server or client, communicate through the integrated PROFINET interface

Through loadable blocks, communication services can be established between S5 communication partners and Siemens devices.

These services include:

• S5 compatible communication via PROFIBUS and industrial Ethernet
• Standard communication via PROFIBUS and industrial Ethernet (non Siemens systems)

Unlike global data, communication connections must be established to achieve communication functionality.

Integrate into IT environment

Through SIMATIC S7-300, modern IT environments can be easily connected to automated engineering environments. By using CP 343-1 Advanced, the following information technology functions can be achieved:

• IP routing;
  Using the IP access list, forward IP V4 packets to the controlled PROFINET interface at a speed not lower than Gigabit.
• Web server;
  Using a standard browser, you can browse HTML web pages up to 30 MB that can be freely defined; Process data in one's own file system through FTP
• Standard diagnostic page;
  All modules inserted into the installation rack can be quickly diagnosed in the factory without the need for additional tools.
• E-mail;
  Send an email directly authenticated from the user program. The email client is designed with notification function, which can directly notify users in the control program.
• Communicate through FTP;
  Most operating system platforms provide open protocols
• Designed with a 30 MB RAM file system, it can be used as an intermediate storage for dynamic data.

The S7-300 PROFINET CPU is integrated with a web server. Therefore, the information of S7-300 station can be read out using a standard web browser:

• CPU General Information
• Diagnostic buffer contents
• Variable Table
• Variable state
• Module Status
• Report to the police
• Information about Industrial Ethernet
• PROFINET Node Topology

Write access to the S7-300 CPU can also be performed via this web server through user-defined pages.

Isochronous synchronization mode

By using the system function "synchronous mode", synchronous coupling can be achieved

• Distributed signal acquisition
• PROFIBUS/PROFINET signal transmission and
• program execution

Suitable for constant bus cycle time in PROFIBUS/PROFINET.

Create an automated solution that captures and processes input and output signals at constant intervals (constant bus cycle time). Simultaneously create consistent partial process images.

Through the constant bus cycle and synchronous signal processing of distributed I/O, S7-300 ensures repeatable and defined process response time.

Provides a large number of components that support synchronous mode system functions, which can be used to handle demanding tasks in fields such as motion control, measurement value acquisition, and high-speed control.

In distributed automation solutions, SIMATIC S7-300 can open up important application areas for high-speed processing operations, achieving * accuracy and repeatability. This means that it is possible to increase production while providing constant quality.

Module diagnosis and process monitoring

Many input/output modules of SIMATIC S7-300 have intelligent functions:

• Monitoring signal acquisition (diagnosis)
• Monitor signals from the process (hardware interrupts)

Diagnosis

The diagnostic function can be used to determine whether the signal acquisition (for digital modules) or analog processing (for analog modules) of the module is working in the * state. In diagnostic analysis, it is necessary to distinguish between parameterizable and non parameterizable diagnostic messages:

• Diagnostic messages with adjustable parameters:
  Diagnostic messages will only be sent when enabled through appropriate parameter settings.
• Diagnostic message with non configurable parameters:
  These messages are automatically sent, meaning they are not related to parameter settings.

If a diagnostic message is in an active state (e.g. 'no sensor input'), the module will trigger a diagnostic interrupt (if parameters have been set for the diagnostic message, the interrupt will only be triggered after the corresponding parameters have been set). The CPU will interrupt the processing of user programs or low priority tasks, and handle related diagnostic interrupt blocks (OB 82).

Digital input/output module
Diagnostic message	Possible causes of malfunction
Sensorless power supply	Sensor power overload Sensor power supply short circuited to M
No external auxiliary voltage	Module without power supply voltage L+
No internal auxiliary voltage	Module without power supply voltage L+ Internal module fuse faulty
The fuse is blown	Internal module fuse faulty
The parameters in the module are incorrect	The parameters transmitted to the module are incorrect
The time monitoring function has been addressed (watchdog)	Regularly experiencing high electromagnetic interference Module malfunction
EPROM malfunction	Regularly experiencing high electromagnetic interference Module malfunction
RAM malfunction	Regularly experiencing high electromagnetic interference Module malfunction
Hardware interrupt loss	The speed at which hardware interrupts arrive exceeds the processing capacity of the CPU

Analog input module
Diagnostic message	Possible causes of malfunction
No external load voltage	Module no-load voltage L+
Configuration/parameter setting error	The parameters transmitted to the module are incorrect
Common mode error	Input (M -) and reference potential (M) of the measurement circuitANA）The potential difference U between themCMtoo high
disconnect	The resistance of the sensor circuit is too high Line interruption between module and sensor Channel not switched (disconnected)
Below the lower limit of the measuring range	The input value is below the range, and the possible cause of the malfunction is: Range of 4 to 20 mA, 1 to 5 volts: Sensor polarity reversed; Selected incorrect measurement range Other measurement ranges: The selected range is incorrect
Exceeding the upper range limit	The input value exceeds the range value

Analog output module
Diagnostic message	Possible causes of malfunction
No external load voltage	Module no-load voltage L+
Configuration/parameter setting error	The parameters transmitted to the module are incorrect
Short circuit to M	Output overload Output QV to MANAshort circuit
disconnect	The resistance of the actuator is too high Line interruption between module and actuator Channel not used (disconnected)

Hardware Interrupt

Hardware interrupts can monitor process signals and trigger responses to signal changes.

• Digital input module:
  According to specific parameter settings, this module can trigger hardware interrupts for each channel group on the rising edge, falling edge, or both rising and falling edges of signal state changes. The CPU will interrupt the processing of user programs or low priority tasks, and handle related diagnostic interrupt blocks (OB 40). The signal module can buffer one interrupt per channel.
• Analog input module:
  By setting upper and lower limits, the working range can be defined. The module compares the digital measurement values with these limits. If the measured value violates any of the limits, it will trigger a hardware interrupt. The CPU will interrupt the processing of user programs or low priority tasks, and handle related diagnostic interrupt blocks (OB 40). If the limit value is higher/lower than the over/under range value, no comparison will be made.

S7-300F

Work Mode

The safety function of S7-300F is included in the F program of the CPU and located within the fault safety signal module.

The signal module monitors the output and input signals through differential analysis and testing signal injection.

Through regular self checks, command testing, and logical program execution checks in chronological order, the CPU can check whether the controller is running properly. In addition, I/O status can also be checked through sign of life requests.

If a fault is diagnosed in the system, switch the system to a safe state.

Programming

The security related programs of CPU 315F are developed using ladder diagrams (LAD) and functional diagrams (FBD) in STEP 7 language. The scope of functions and data types related to operation are limited to being set here. By using specific formats and parameters during compilation, security related programs can be created. In a single CPU, standard programs can run simultaneously (coexist) with fail safe programs without any restrictions.

Another component of this software package is the F library, which comes with programming instances of TUV approved safety related functions. These programming instances can be changed, but the changes must be authenticated again.

S7 F Distributed Security Options Software Package

When developing safety related program segments, the option software package "S7 F Distributed Safety" must be used. This software contains all the functions and blocks required to create an F program. To run S7 F Distributed Safety, STEP 7 version V5.1SP3 or higher must be installed.

Technical Specifications

General Technical Data
Protection level	IP20， Compliant with IEC 60 529
ambient temperature
During horizontal installation	0 to 60 ° C
When installed vertically	0 to 40 ° C
Relative humidity	10-95%, non condensing, equivalent to relative humidity (RH), stress level 2, in accordance with IEC 61131 Part 2
atmospheric pressure	1080~795 hPa (equivalent to an altitude of -1000~+2000 m)
insulation
< 50 V	500 VDC test voltage
< 150 V	2500 V DC test voltage
< 250 V	4000 V DC test voltage
Electromagnetic Compatibility	Electromagnetic compatibility directive requirements; Immunity, according to standard IEC 61000-6-2
Pulse shaped interference variable	Test basis: Electrostatic discharge: IEC 61000-4-2; Sudden pulse: IEC 61000-4-4; Surge pulse: IEC 61000-4-5
Sine interference variable	Test basis: High frequency radiation complies with IEC 61000-4-3, High frequency decoupling complies with IEC 61000-4-6
radio frequency interference	Interference radiation: EN 50081-2 Test according to the following standards: Conduct radiation interference testing according to EN 55016: A-level limit (measuring distance of 10 meters) Electromagnetic interference from current power supply, EN 55011： A-level limit, Group 1
Mechanical load
Vibration resistance	Frequency range: 10 Hz ≤ f ≤ 58 Hz Continuous: amplitude 0.0375 mm Intermittent: amplitude 0.75 mm Frequency range 58 Hz ≤ f ≤ 150 Hz Continuous: Constant acceleration of 0.5 g Intermittent: Constant acceleration of 1 g Test standard IEC 60068-2-6 Test method: 5 Hz ≤ f ≤ 9 Hz， Constant amplitude of 3.5 mm, 9 Hz ≤ f ≤150 Hz， 恒定加速度 1 g; Vibration duration: 10 times in each of the X, Y, and Z directions
impact resistance	Test standard IEC 60068-2-27 Test method: Half sine wave: Impact strength 15 g (peak), duration 11 ms; Impact direction: in the positive and negative directions of each of the three mutually perpendicular axes