Additional Topic forProcess Control SessionalBy International Institute for Advanced Training on Control and Automation(IIATCA)

Machine Vision and Motion ControlImage Acquisition Applications:Frame grabber: Blob analysis: Cell counting, Area calculation, OCRLine Scan Camera: Alignment testingMotion Control: ApplicationsFactory Automation/ Industrial RobotsAutomated Test Sequencing machinesHazardous chemicals processing (explosive powder packaging etc.)

PLC, DCS and Modern Plant Control Systems

Programmable Logic Controller (PLC)Pre-PLC era: Electro-mechanical relay and pneumatic couplingsPLCs are microcomputers developed to handle industrial control applicationsFirst CPU-based PLC in 1977 by Allan Bradley corp. with an Intel 8080 processor5.5 billion PLCs up to 1997, largest use in Europe (45%), Japan (23%) & US (7%)Many modern PLCs are Ethernet enabled

PLC Architecture

Distributed Control System (DCS)Control logic is distributed across multiple devicesPLC Networks alone and as part of a heterogeneous network can be called a DCSMost current PLC communication protocols are proprietary, making DCS based on them also proprietaryExpensive to purchase, maintain and expandIndustry trend is toward open standards

Industrial CommunicationOpen standards lead to open systems

Background InformationSampling Rate: Nyquist TheoremSignal ConditioningMultiplexAmplifyFilterIsolateExciteComplete bridge configurationsBandwidthSerial and Parallel: Benefits of serial comm.

Serial Communication: ApplicationsMicrocontroller & Flash memory I/OMarine, Automotive and Aviation CommunicationManufacturing & Factory AutomationProcess AutomationHigh Channel count systems: Ammonia, PE plantDistributed Control: PipelinesTelemetry and Remote Control: Nuclear, Biohazard and Hazardous chemical processing

Serial Hardware SpecificationEIA RS RS-232, 232/C, 232/DLaboratory InstrumentsPC Serial PortRS-422, RS-423HPIB/GPIBRS-485: Industrial networksUSB

erial is a very common protocol for device communication that is standard on almost every PC. It is not to be confused with Universal Serial Bus (USB). Most computers include two RS-232 based serial ports. Serial is also a common communication protocol that is used by many devices for instrumentation; numerous GPIB-compatible devices also come with an RS-232 port. Furthermore, serial communication can be used for data acquisition in conjunction with a remote sampling device.

The concept of serial communication is simple. The serial port sends and receives bytes of information one bit at a time. Although this is slower than parallel communication, which allows the transmission of an entire byte at once, it is simpler and can be used over longer distances. For example, the IEEE 488 specifications for parallel communication state that the cabling between equipment can be no more than 20 meters total, with no more than 2 meters between any two devices; serial, however, can extend as much as 1200 meters.

Typically, serial is used to transmit ASCII data. Communication is completed using 3 transmission lines: (1) Ground, (2) Transmit, and (3) Receive. Since serial is asynchronous, the port is able to transmit data on one line while receiving data on another. Other lines are available for handshaking, but are not required.

Serial Software Application ProtocolsManufacturing: FIP, DeviceNetAutomotive: CAN, CANOpenProcess Automation:FieldBus:FF (Foundation FieldBus), H1 Foundation FieldBusProfiBus (Process FieldBus) and its variantsHARTEthernet/IP and Fast Ethernet/IP: 10BaseT, T4,TX, FX

Industrial Networking Benefits:Reduced Field Cabling

Industrial Networking Benefits:Multivariable, Bi-directional

Industrial Networking Benefits:Extended Horizon

The Sensor Network

The Device Network

Industrial Networking: OSI Model

The OSI model is universal networking standardComparing with the Internet and FieldBus

Comm. StackApplicationTransportNetworkPhysical

WebHTTPTCPIPRS-232

FieldBusH1PPTPDevice IDRS-485

The Control Network

The Enterprise Network

Real-time ControlIIATCA

Real-time ControlReal-time controlControl loop cycle timeDeterminism and jitterHardware real-time and software real-timeReal-time operating systemsEmbedded and Headless applications

RTC: automotive ECUCycle time: Oven 1 sec, guided missile 10 microsecondDeterminism: PID, elevatorJitter: Error in determinismHW-RT: ECU; Soft-RT: reactor temp. control

Role of the Real-time Controller

The most common misconception associated with real-time performance is that it increases the execution speed of your program. While this is true in some cases, it actually enhances your application by providing more precise and predictable timing characteristics. With these enhancements, you can determine the exact time when certain events will occur.

Real-time performance can be achieved through either hardware or software. To implement a hardware real-time system, you need an accurate clock driving some hardware circuitry. A real-time operating system and programming environment can create a real-time software solution. This software solution offers more flexibility and convenient debugging tools. With it, you can incorporate real-time decision making into your application with a custom algorithm instead of relying on existing hardware circuitry. With some systems, you can achieve a hybrid in which you have the precise timing of hardware controlled real-time combined with the flexibility of software real-time. With real-time control, you can continually monitor and simulate a physical system. Real-time control applications repeatedly perform a user-defined task with a specified time interval separating them. There are many real-time control systems in the world around you such as the cruise control in your car or the thermostat controlling the temperature in your home. There are different ways to measure or describe a real-time control application - control loop cycle time, determinism, jitter, and soft real-time.

End of Class

IIATCA

erial is a very common protocol for device communication that is standard on almost every PC. It is not to be confused with Universal Serial Bus (USB). Most computers include two RS-232 based serial ports. Serial is also a common communication protocol that is used by many devices for instrumentation; numerous GPIB-compatible devices also come with an RS-232 port. Furthermore, serial communication can be used for data acquisition in conjunction with a remote sampling device.

The concept of serial communication is simple. The serial port sends and receives bytes of information one bit at a time. Although this is slower than parallel communication, which allows the transmission of an entire byte at once, it is simpler and can be used over longer distances. For example, the IEEE 488 specifications for parallel communication state that the cabling between equipment can be no more than 20 meters total, with no more than 2 meters between any two devices; serial, however, can extend as much as 1200 meters.

Typically, serial is used to transmit ASCII data. Communication is completed using 3 transmission lines: (1) Ground, (2) Transmit, and (3) Receive. Since serial is asynchronous, the port is able to transmit data on one line while receiving data on another. Other lines are available for handshaking, but are not required. RTC: automotive ECUCycle time: Oven 1 sec, guided missile 10 microsecondDeterminism: PID, elevatorJitter: Error in determinismHW-RT: ECU; Soft-RT: reactor temp. controlThe most common misconception associated with real-time performance is that it increases the execution speed of your program. While this is true in some cases, it actually enhances your application by providing more precise and predictable timing characteristics. With these enhancements, you can determine the exact time when certain events will occur.

Real-time performance can be achieved through either hardware or software. To implement a hardware real-time system, you need an accurate clock driving some hardware circuitry. A real-time operating system and programming environment can create a real-time software solution. This software solution offers more flexibility and convenient debugging tools. With it, you can incorporate real-time decision making into your application with a custom algorithm instead of relying on existing hardware circuitry. With some systems, you can achieve a hybrid in which you have the precise timing of hardware controlled real-time combined with the flexibility of software real-time. With real-time control, you can continually monitor and simulate a physical system. Real-time control applications repeatedly perform a user-defined task with a specified time interval separating them. There are many real-time control systems in the world around you such as the cruise control in your car or the thermostat controlling the temperature in your home. There are different ways to measure or describe a real-time control application - control loop cycle time, determinism, jitter, and soft real-time.