Hierarchia układów sterowania

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1 Hierarchia układów sterowania Enterprise Manufacturing Execution Supervision (SCADA) Group Control Individual Control Field Primary technology Kompleksowy system automatyki Statystyka, planowanie, finanse administration Tok pracy, materiały, interakcje enterprise Nadzór SCADA SCADA = Supervisory Control And Data Acquisition control room Sterowanie grupowe Sterowanie gniazdowe Poziom sterowania miejscowego Czujniki i układy wykonawcze Sensory i aktory A V T Technologia pierwotna Page 1

2 Sterowanie miejscowe Bezpośrednia interakcja z prowadzonym procesem - technologią pierwotną (Primary technology) Sensory i aktory, zbieranie danych, przesyłanie danych, elementarne zadania sterowania i regulacji Sterowanie gniazdowe i grupowe (cell level, group level) unit controllers Poziom gniazdowy: Sterowanie małych fragmentów instalacji: Pomiary próbkowanie, skalowanie, kalibracja Sterowanie regulacja do zadanych wartości, Zadawanie sekwencyjne, ochrona Poziom grupowy: Uporządkowane hierarchicznie lub równorzędnie (peer-to-peer) Koordynacja pracy sterowników poziomu gniazdowego Regulacja działania kompletnego urządzenia linii technologicznej. Zadawanie parametrów pracy dla poziomu gniazdowego Page 2

3 Lokalny interfejs HMI (human machine) Czasami, do poziomu sterowania grupowego przyporządkowany jest lokalny interfejs HMI.(tutaj: pakowanie cementu) TakŜe czasami rezerwowy panel sterowania ręcznego Poziom nadzorowania: Interfejs HMI Pomieszczenie sterowania (control room) Ściana synoptyczna Dawniej wszystkie czujniki były bezpośrednio połączone do ściany synoptycznej Page 3

4 Poziom nadzorowania stanowisko operatora Poziom nadzorowania (SCADA = Supervisory Control and Data Acquisition) - wyświetla bieŝący stan procesu - wyświetla historię (alarmy, zdarzenia) oraz trendy - umoŝliwia dostęp do dokumentacji i podręczników - komunikacja i synchronizacja z innymi układami SCADA Standard amerykański ANSI/ISA 95 standard Source: ANSI/ISA Page 4

5 Przykład: Siemens WinCC Czas odpowiedzi poziomów Poziom planowania ERP (Enterprise Resource Planning) Poziom zarządzania Poziom nadzoru Poziom sterowania DCS (Distributed Control System) PLC (Programmable Logic Controller) MES (Manufacturing Execution System) SCADA (Supervisory Control and Data Acquisition) ms sekundy godziny dni tygodnie miesiące lata Page 5

6 Scentralizowana architektura sterowania (klasyczna) Central Computer (Mainframe) Group Control Group Control Group Control PLCs Sensors, Actors plant Komputer centralny wyłącznie monitoruje i przekazuje polecenia pomiędzy sterownikami PLC Zdecentralizowana architektura sterowania Decentralized Control System (DCS) engineering workstation operator workstation data logger control bus controller controller controller controller field bus plant Sterowniki mogą się komunikować pomiędzy sobą, bez konieczności angaŝowania centralnego komputera Page 6

7 Magistrale komunikacyjne station Process Pictures, Process Data Base, Logging Disk Operator Panel Mimic board station open network: TCP/IP,... workstation bus instrument bus (mimic board) process bus (500m.. 3 km) pool P P P C I/O MEM I/O directly coupled input/ output PLC nodes (multi-processors) P P C P MEM BC control stations sensor bus (30m..2 km) (0, m) node bus fieldbus station bus sensor bus transducers valve thermo-couple position M motor plant (usine, Werk) Przykład: Zarządzanie produkcją enterprise network production planning scheduling maintenance quality control plant network transportation cell control manufacturing cell control floor network RC milling machine rail-guided vehicle Page 7

8 Przykład: Sterowanie elektrownią (BBC, 1980) Układy sterowania wyglądają podobnie Przykład: System TotalPlant firmy Honeywell (2003) Page 8

9 509 -BOD 24vdc Przykład : System NetLinx firmy Rockwell (Allen-Bradley) Programmable Device Support PC Desktop PC with excel EtherNet / IP Controller and Bridge Servo ControlNet HMI Linking Device Drive Bridge or Linking Device DeviceNet HMI Modular I/O Micro PLC Sensor Block I/O Przykład: System PlantWeb firmy Emerson's Page 9

10 Przykład: redundantny system firmy ABB Plant Network / Intranet Firewall Client/server Network Workplaces (clients) Enterprise Optimization (clients) 3rd party application server Mobile Operator Control Network connectivity server aspect server application server engineering workplace Serial, OPC or fieldbus Field Bus Redundant AC 800M Programmable Logic Controller AC 800C Field Bus touch-screen 3rd party controllers, servers etc Zastosowanie Internetu (przykład: Alstom) Page 10

11 Komunikacja bezprzewodowa ( Schneider) Nie ma przewodów, lecz struktura pozostaje Komunikacja master - slave Page 11

12 Komunikacja rozgłoszeniowa Transactions on Modbus Networks Master-Slave relationship QUERY - RESPONSE» MASTER - can initiate transactions (queries).» SLAVES - respond by supplying the requested data to the master or by taking the requested action. RTU or ASCII Transmission modes Slave Addresses are individual slave addresses Broadcast address = 0 Transmission baud rate, and error checking. RS232,422 or 485. Serial interfaces that define the connector pinouts, cabling, signal levels Page 12

13 Query Response Query-Response Cycle The function code tells the slave device what kind of action to perform. The data byte contains the slave register to start at and how many to read. The error check field validates the integrity of the message In a normal response the function code in the response echos the query and the data bytes contain the data collected from the slave. If an error occurs, the function code is modified to indicate an error and the data bytes will contain an error code. Page 13

14 Transmission Mode - ASCII ASCII - American Standard Code for Information Interchange Main advantage of this mode is that it allows time intervals of up to one second to occur between characters without causing an error Coding System - Each eight-bit byte in a message is sent as two ASCII characters Character Framing - Bit Sequence» 1 Start bit» 7 data bits, least significant bit sent first» 1 bit for even/odd parity - no bit for no parity» 1 stop bit if parity is used - 2 bits if no parity Error Check Field» LRC - Longitudinal Redundancy Check Transmission Mode - RTU RTU - Remote Terminal Unit Main advantage of this mode is that its greater character density allows better data throughput than ASCII for the same baud rate Coding System - Eight bit binary, each eight-bit byte in a message contains two four-bit hexadecimal characters Character Framing - Bit Sequence» 1 Start bit» 8 data bits, least significant bit sent first» 1 bit for even/odd parity - no bit for no parity» 1 stop bit if parity used - 2 bits if no parity Error Check Field» CRC - Cyclical Redundancy Check Page 14

15 ASCII Framing Modbus Message Framing Messages start is a colon(:) character and ends with a carriage return-line feed (CRLF) RTU Framing Messages start and end with a silent interval of at least 3.5 character times. Implemented as a multiple of character times at the baud rate being used. Message Frame - Address Field Address Field Valid Slave device address are in the range of » Individual slave addresses are assigned A master addresses a slave by placing the slave address in the address field of the message. A slave places its own address in the address field of the response to let the master know which slave is responding Address 0 is used for the broadcast mode, which all slave devices recognize. START ADDRESS FUNCTION DATA ERROR CHECK END Page 15

16 Modbus Function Codes Function codes - tells the slave what kind of action to perform FC Description Address range 01 Read Output Status Read Input Status Read Multiple Registers Read Input Registers Single Bit/Coil Write Single Register Write Multiple Bit/Coil Write Multiple Register Write START ADDRESS FUNCTION DATA ERROR CHECK END Data Field Contents of the Data Field Master to Slave query - contains information which the slave uses to take the action defined by the function code» Discrete and Register addresses» Quantity of items to be handled» Count of actual data bytes in the field Slave to Master response -» No error - contains data requested» If error occurs - contains an exception code START ADDRESS FUNCTION DATA ERROR CHECK END Page 16

17 Error Checking Field Frame Checking - LRC or CRC ASCII - Longitudinal Redundancy Check (LRC) RTU - Cyclical Redundancy Check (CRC) Parity Checking - Even, Odd or No When the message is transmitted, the parity bit is calculated and applied to the frame of each character. The receiving device counts the quantity of 1 bits and sets an error if they are not the same as configured for that device START ADDRESS FUNCTION DATA ERROR CHECK END Field Contents in Modbus Messages - Query Example: Modbus Query Field Name Example (hex) ASCII Characters RTU 8-Bit Field Header :(colon) none Slave Address Function Starting Address HI Starting Address LO 6B 6 B No. of Registers HI No. of Registers LO Error Check LRC (2 chars.) CRC (16 bits) Trailer CR LF none Total Bytes 17 8 Page 17

18 Field Contents in Modbus Messages - Response Example: Modbus Normal Response Field Name Example (hex) ASCII Characters RTU 8-Bit Field Header :(colon) none Slave Address Function Byte Count` Data HI Data LO 2B 2 B Data HI Data LO Data HI Data LO Error Check LRC (2 chars.) CRC (16 bits) Trailer CR LF none Total Bytes Data Transmission Speeds Baud - designates bits per second or bps Standard values are: 300, 600, 1200, 4800, 9600, 19200, 38400, 57600, and Data Transmission Rates depend on:» Interface - type and complexity of circuitry» Communication medium (twisted pair, fibre, ect.)» Communication Link - distance between two ends» Protocols Page 18

19 Data Communication Standards Interface Standard - defines the electrical and mechanical details that allow communications equipment, from different manufacturers, to be connected together and to function efficiently. Example: EIA : Electronic Industry Association RS : Recommended Standard 232 : Standard No. 232 C : Revision C RS232 Main Features Communication is Point to Point Voltage signals are: Logic 1 : -3Volts to -25Volts Logic 0 : +3Volts to +25Volts Reliable Communications up to 50ft Pins most commonly used: Data Lines» Pin 2 Transmit Line» Pin 3 Receive Line Control Lines» Pin 4 RTS Request to Send» Pin 5 CTS Clear to Send» Pin 7 GND Ground/Signal Common Page 19

20 Sygnały RS-232C Modem - DCE Power supply Transmit circuits Receive circuits Test and control circuits Terminal - DTE Protective gnd Signal gnd Transmitted data TxD Request to send RTS Clear to send CTS Carrier detect CD Received data RxD Dataset ready DSR Data terminal ready DTR Ring indicator RI RS422- RS485 Połączenie róŝnicowe, punkt-punkt Połączenie róŝnicowe, wielowęzłowe Page 20

21 RS422 - Main Features Communications is Point to point 5 Volt differential voltage on two wires - produced by line driver Logic 0 Voltage on A(+) is greater than B(-)» +2 Volts to +6 Volts Logic 1 Voltage on A(+) is less than B(-)» -2 Volts to -6 Volts Distances up to 4000ft Four Wires and Ground Transmit Data A(+) Transmit Data B(-) Receive Data A(+) Receive Data B(-) Ground RS485 Main Features Communications is multidrop - 32 devices 5 Volt Differential Voltage on two wires Logic 0 Voltage on A(+) is greater than B(-)» +1.5 Volts to +6 Volts Logic 1 Voltage on A(+) is less than B(-)» -1.5 Volts to -6 Volts Distances up to 4000 ft Two Wires and Ground Transmit Receive Data A(+) Transmit Receive Data B(-) Ground Page 21