[Abstract] This article focuses on the hardware functions and architecture of the SIEMENS control system, and analyzes and explains the architecture design scheme and the functional application of the modules.
[Keywords] SIEMENS SIMATIC PLC rack
Foreword
In electrical control systems, SIEMENS' automatic control systems are widely used in advanced steel rolling production lines both domestically and internationally. They represent mainstream hardware and software applications that closely integrate transmission equipment with computer control systems. Their characteristics include powerful functionality, strong standardization and versatility, and the ability to be used simultaneously in various main/auxiliary drive control systems. This enables control of various functions, including parameter setting, equipment operation control, user interface, program monitoring, digital signals, graphical curves, actual status of transmission equipment, fault alarm functions, and remote connection.
1. Description of SIEMENS Automation Systems
Siemens uses microprocessor-based systems to implement all functions of basic automation—process control, programming functions, support functions, and media systems.
The automation system is divided into several automation units, each controlled independently. The CPUs operate in parallel, cooperating to process programs. Each automation unit is connected to different devices for sensing and actuation (including power supply and drive control). Sensors directly input process control data, such as the pressing system, the screw-in system, and the PLC main ramp generator, communicating with each other via real-time cable bus connections (parallel buses within the sub-racks, fiber optic coupling between different sub-racks) to ensure high dynamic switching between controls, which has a significant impact on overall performance and rolling results. Connections are established through intelligent terminal boxes (remote I/O) and via bus cables to the central controller.
2. SIEMENS Control System Architecture
2.1 Data SIMATIC Ethernet: Star network configuration. All data terminals are connected point-to-point to the star coupling via transceiver cables, or attached to optical transceivers via dual fiber optic cables.
2.2 The following systems will be connected to the SIMATIC Ethernet bus system: SIMATIC ICTDC digital control system, SIMATIC ICS7 digital control system, professional computer and operator communication and monitoring system, and SIMATIC network external system.
2.3 PROFIBUS Fieldbus Network: SIMATIC PROFIBUS is a powerful bus system for low to medium media range capabilities. PROFIBUS can connect programmable controllers, small field units, and various automation components, such as programming units and computer components.
2.4 SIMOVER™ ASTERDRIVES and SINAMICS SM120 are used in all drive systems.
The 2.5 SIMATIC TDC is used for high-speed process control, binary interlocking, automatic programming, and open/closed-loop control within the rolling mill.
2.6 SINAMICS SM150 is used to control the main drive motors of the roughing mill and finishing mill.
2.7 SIMATIC S7 is used for general process control, media system program control, cooling bed zone, shearing line, and finishing mill zone.
3. Hardware Function Analysis
3.1 SIMATIC TDC PLC
The SIMATIC TDC PLC CPU is used for the main control of the automation system (data processing, program speed ramp generator); roughing mill, vertical roll (if used), and finishing mill stand control functions. This system is stand-based, with components selected based on the number and type of sensors directly connected to the PLC in the automation functions and fast control loop.
3.1.1 Sub-rack UR5213
The UR5213 sub-rack is the mechanical foundation of the SIMATICTDC. The sub-rack integrates the system power supply and system fan. A high-performance 64-bit rear-wire bus allows data transfer between modules within the rack.
3.1.2 CPU551
The CPU module can perform general open-loop and closed-loop control and arithmetic tasks, and contains approximately 2.5 times the performance of a Siemens CPU module (latest generation Siemens). PM6.
8 digital inputs, 4 of which are interruptible.
5×7 LED dot matrix
Local service serial RS232 interface
MC5xx program memory module slot
Sampling time 100μs
32MB SDRAM
512KB synchronous cache
266HZ
64-bit RISC floating-point CPU
4MB flash
CPU buffer supported by onboard battery
3.1.3 Communication Module CP50M1
The CP50M1 communication module contains two PROFIBUSDP/MPI interfaces and buffer memory for establishing communication between CPUs. The interfaces can function as PROFIBUSDP/MPI masters, PROFIBUSDP slaves, or simultaneously as PROFIBUSDP/MPI slaves, PROFIBUSDP masters, and MPI nodes (stations).
3.1.4 Communication Module CP51M1
The CP51M1 communication module provides an industrial Ethernet interface. This module can be used to perform the following tasks:
It can exchange and process data with other CP51M1 and SIMATIC industrial Ethernet modules.
Using WinCC for visual data and information processing:
3.1.5 I/O Module SM500I/O: One panel contains the following I/O capacity:
8×AO+/-10V, 8xAI+/-10V
16×DO24V, 16xDI24V
4×SSI absolute encoder inputs, 4×incremental encoder inputs
4×Interrupt Input 5V
CP52M0 Global Data Memory (GMD) Mode
The GMD system's central memory is 2MB, located in the CP52M0 global memory module. This module handles all data transfers between programs in the coupled rack. The rear interconnect bus handles data transfer between the CP52IOGDM interface module and the CP52M0.
The CP52M0 reads all CP52IO fiber optic cable interface error and diagnostic loggers, installed inside the GDM sub-rack. It detects and estimates the central operating status of all fiber optic cable interfaces. The results are output to the CP52M0 digital output for additional estimation.
3.2.1 CP52IOGDM Interface Module: The CP52A0GDM channel module in the sub-rack is connected to the CP52IOGDM interface module via a fiber optic cable.
3.2.2 CP52A0GDM Channel Module: Each sub-rack is equipped with a CP52A0GDM channel module, which is connected to the GDM.
3.2.3UR5213 Sub-rack: GDM sub-racks do not require application software configuration.
3.2.4 The CP52M0 and CP52IOGDM modules operate in a special mode, which is very fast.
3.3 SIMATIC S7 PLC
The SIMATIC S7 CPU circuit is the media terminal for the SIMATIC PLC. It is selected for controlling the media system of the shearing and finishing mill lines, as well as the MULPIC, straightener, etc. Due to its integrated design, the PCS7 visualization platform uses the S7-400 PLC.
3.3.1 Sub-rack UR1: The UR1 rack is the hardware foundation of SIMATICS7. It has 18 slots and a power supply.
3.3.2 Sub Rack UR2: The UR2 rack is the hardware foundation of SIMATICS7. It has 9 slots and a power supply.
3.3.3 CPU416: A general-purpose open-loop and closed-loop control and arithmetic task CPU module. Its main parameters are shown below:
Integrated user memory programming 0.8MB, data 0.8MB
Maximum load memory 64MB
Maximum counter 512, maximum timer 512
UR1 rack multi-processor up to 4 CPUs
Minimum cycle time 10msec
Integrated clock
CPU buffer supported by onboard battery
CPU module MPI interface integration
CPU module PROFIBUSDP interface integration
3.3.4 Communication module CP443-5: Provides an additional PROFIBUS P interface.
3.3.5 Communication Module CP443-1: Provides an industrial Ethernet interface. This module can exchange and process data with other CP443-1 and SIMATIC industrial Ethernet modules: using WinCC for visual data and information processing, and providing functions such as TCP/IP and ISO/OSI protocols.
3.4ET200 Non-centralized I/O System
The ET200 is a modular remote I/O system that assigns configurations to SIMATIC PLC controllers. It allows programs to use SIMATIC family modules directly adjacent to each other (in a central electrical room, switchgear room, or workshop).
The ET200 connects to a SIMATIC PLC (S7 or TDC) via PROFIBUS-DP, and field devices with integrated PROFIBUS-DP interfaces connect directly to the fieldbus. The ET200 has the following features:
The ET200 is located near the sensors and actuators. Remote I/O is grouped according to field location.
The ET200M is used for sensors, actuators, and main control consoles. The ET200B is used for small control consoles and control panels.
The central controller and the first ET200 station are connected via fiber optic cable.
COMPROFIBUS software provides a simple and convenient system configuration aided by graphical symbols.
Module replacement is convenient, and it can be performed even when there is no reverse signal in the power supply state (hot exchange).
Intelligent module counters, timers, and verifiers
Key-coded plugs: To prevent errors when replacing modules, the bus units and modules have a "lock-lock" coding system. Therefore, incorrect module types cannot be inserted.
3.5 SIMATICS 7-300F Emergency Stop PLC
The emergency stop system is isolated by wiring, and the diagnostic system records are activated. Due to communication capacity, each emergency stop PLC can handle up to 15 emergency stop zones.
A fail-safe control system for a rolling mill area, SIMATICS 7-300F
Emergency Mushroom Button
PROFIBUS connects to the panel control system and diagnostic system.
The SIMATICS 7-300F is permanently mounted in the compartment and fully wired to the terminal. The compartment contains all necessary accessories, such as power supplies, auxiliary circuit breakers, and relays.
3.6 SIMATICNET Communication
The SIMATICNET control system utilizes the SIMATICNET industrial communication network. All SIMATICNET products are specifically designed for industrial applications. For computer networks, standard communication components, such as those from Cisco Systems, are used. The following SIMATICNET product family bus systems are used: Industrial Ethernet such as System Bus 10Mbps, 100Mbps thread; PROFIBUS-DP fieldbus.
3.6.1 Industrial Ethernet Bus (H1)
Industrial Ethernet can connect up to 1000 stations. It operates at speeds of 10Mbps or 1000Mbps, providing large data capacity. It supports TCP/IP protocol and SINECH 1OSI 802.3, and can use three-core coaxial cable, industrial twisted-pair cable, and fiber optic cable. The Ethernet topology is star. Twisted-pair cable connections are <100m, and multimode fiber optic connections are >100m.
3.6.2 PROFIBUS DAP Fieldbus
PROFIBUS (Process Fieldbus) is a powerful network for low to medium performance. PROFIBUS meets EN50170 requirements, ensuring open connection components and consistency with other standards. PROFIBUS uses a token passing principle for accessing auxiliary master and slave devices. There are differences between active and passive network stations. Only the active station receives the token; that is, authorization is transmitted from one active station to another within a specific time. The system automatically detects whether a station is missing or a new station has joined the network. The PROFIBUS network topology is star-shaped. Stations are divided into active and passive stations: active stations include PLCs, industrial computers, and programming units; passive stations include ET200 remote I/O units, SIMOVERT main drives, SINAMICS SM120, rectifiers, sensors and actuators, external systems, and, depending on the connection distance, twisted-pair cables or fiber optic transceivers (Optical Bus Termination, OBT), etc.
4. Conclusion
Leveraging SIEMENS' powerful hardware and software control capabilities, the automatic control system for heavy plate rolling lines provides strong technical support for equipment control and system operation, improves product control quality, optimizes system parameters, and exhibits high system stability. It is the mainstream application equipment for automatic control systems in major steel production lines in China.
