Bus terminals for use in extreme climates

The ET Bus Terminals from Beckhoff Automation extend the temperature range for selected standard Bus Terminals and Couplers, reportedly making them ideal for outdoor applications such as solar power plants.

Beckhoff Automation Extended Temperature (ET) Bus Terminals extends the operating temperature range for selected standard Bus Terminals and Couplers to between -4 and 140°F. The storage temperature range of the ET Bus Terminals is specified as -40 to 185°F. 

With the broadened operating temperature range for selected standard Bus Terminals and Couplers, the ET Terminals are ideal for "outdoor applications," according to Beckhoff Automation. Typical fields of use include alternative energy systems such as wind, solar or tidal power plants, which in many cases operate under extreme climatic conditions. 

The I/O terminals selected for the extended temperature range cover the most common areas of application and a wide range of signal types, according to Beckhoff Automation. The Beckhoff CX5000 series Embedded PCs with direct I/O connection and low-heat dissipation are designed for the extended temperature range. When paired with the new ET Bus Terminals, this represents a complete controller and I/O solution for extreme environments. 

Via Beckhoff’s K-bus technology, the new ET Bus Terminals are compatible with the entire Bus Terminal product range and can function with more than 15 fieldbus networks and protocols.

System-based Automation

State-of-the-art automation & control systems have to guarantee the simple and safe operation of a hydro power plant.

Typically there are different possibilities for local control (e.g. unit control board) as well as remote control (central control room and/or dispatching centre).

In emergency situations the system has to lead the corresponding part of the plant to a predefined, safe operating state automatically.

The essential requirements to a hydro power plant automation & control system are easy adaptation to the existing plant and separation into independent functional parts. The overall control of the plant needs to take care of operational regulations as well as the primary systems (e.g. unit, dam gate) require an integrated control of these parts.

All process signals should be managed without multiple engineering.

In order to allow an easy future expansion, the local and remote communication of the system has to be based on international communication standards.

Reduction of spare parts by using one hardware platform as well as the reduction of maintenance and service activities by integrated remote diagnostic functions should reduce the maintenance costs to a minimum.

Step-by-step expansion and the integration of further parts of the plant (e.g. switch yard, station service) should easily be possible at any time.

The Common Solution

Dividing the overall system into autonomous functional areas increases the availability of the total plant. The definition of different functional areas are the result of your structural conditions and depends on your primary technology (units, dam gates, switchyard). In normal operation, the corresponding part of the process is monitored and controlled, whereas in case of emergency, switchover to a safe operation state will be performed.

• Functional area "Unit Control Board"
  In addition to the basis layout of the unit control board (compact or decentralised, singular or redundant configuration), the availability can additionally be increased by subsplitting the unit control board into functional islands. Direct process and transformer interfaces (binary 220 VDC, VT/CT 100/110/220 VAC, 1/5 A) cut down the costs of the process interface level by reduction of interposing relays, transducers and terminal points. Modern touch panel PC's are used as the standard solution for the local control.

• Functional area "Central Control Room"
  The HMI system in the local control room of the power plant can be configured as compact system or as a redundant multi-user system. Based on project experience over many years we can easily adapt our standards to your operational requirements (process displays, user guidance, alarming concept, reporting, ...).

• Functional area "Switch Yard"
  The automation of the functional area switchyard is based on the proven centralised or decentralised configurations using the same hardware platform as the unit control board.

Our Products

• SICAM 1703
  The automation & control system SICAM 1703 is characterised by innovative system concepts, 32-Bit multi-processor technology, powerful communication capabilities and one unique engineering tool. Based on optimised mechanical modular design, signal numbers adapted to the process needs and direct process interfaces (e.g. voltage transformer) the system ideally fits for decentralised as well as centralised concepts. Due to design for industrial use, the system withstands the climatic and electro-magnetical environmental conditions easily.

• 250 SCALA
  The 200 product family represents a full-featured modern SCADA-system for hydro power plants. Integrated scalability allowing the use in all applications leading from local operation via touch-panel through local control rooms to huge main control centres and ergonomically HMI-concepts are the basis for safe operation of the process.

• HyNET
  The HyNET product family is the basis of the safe communication in the power plant automation system. It interconnects all internal relevant components inside and outside of the plant. The communication concept makes use of LAN/WAN-technologies as well as conventional communication and will be especially selected and adapted according to the plant requirements

• TOOLBOX II
  The TOOLBOX II product family provides most modern software tools for data management, system engineering and comprehensive system diagnosis, supporting the engineering and service staff.

Flexible Turbine Control

State-of-the-art turbine controllers must meet the highest demands concerning safety, economy and availability. The basic requirements are a hardware platform suitable for industrial application and the use of international standards. Most modern, graphical user interfaces should allow for simple operation of the turbine controller. In addition, efficient remote parameterisation and diagnostic functions should be available for quick and simple maintenance and service access. Operational safety must be guaranteed even under the most difficult ambient conditions (e.g. moisture, EMC). Also the sensor technology for picking up the process signals must be designed to meet the highest requirements. Particularly the sensors for speed and servo motor position should be drift-free and thus be maintenance-free. The mechanical design should be optimised towards minimum space requirements.

The Common Solution

Since both the controller hardware and the standardised controller algorithm are modular, the application can individually be adjusted to the requirements of the power plant. After a functional test of the controller in the workshop, erection and commissioning is carried out by experienced specialist engineers. First priority is given to the safety of the plant at any time. Comprehensive services, spare part guarantees and training classes complete our scope of delivery.

Our Products

• TC 1703
  The modular TC 1703 offers all advantages of a modern, scalable turbine controller for the use as an individual unit, but also as an integrated part within the power plant automation system. Powerful 32-Bit microprocessor technology, integrated diagnostic functions and various configuration concepts assure highest availability. The modular system design allows centralised and decentralised interfacing to the peripheral signals. Efficient communication concepts allow for a simple integration into the existing plant. For quick hardware exchange, a modern plug-and-play concept is available.

• CAEx plus
  CAEx plus is a graphical engineering tool acc. to IEC 61131-3, which stands out for its simple operation and user-friendly programming.

• Reglerapplikation
  The turbine controller TC 1703 can be universally used for all turbines. lt can make use of standard PID schemes, advanced control algorithms with adaptable parameter setting values or state based control algorithms.
  
  Operation Modes
  - Speed control
  - Power control
  - Discharge control
  - Water level control
  Integrated Control Functions
  - Surge control
  - Adaptive Cam Control (ACC module)
  - Flow Calculation (FCA module)
  - Surge tank Protection Module (SPM module)
  - and others

Due to the possibility of integrating unit protection as well as start/stop sequencing, TC 1703 can also be used as a complete compact control system.

Power Plant Management

Your Target

For single power plants as well as for power plant cascades, power production has to be maximised whereas the costs have to be reduced to a minimum.

Modern power plant management systems have to fulfil these tasks in a very efficient way. Beside the plant's operational requirements (e.g. maintenance cycle) the system has to take into account a number of external regulations (water management, contracts, environmental regulations).

Production planning requires different modules for forecasting and optimisation. Information has to be provided to other applications (e.g. commercial and administrative software tools) via standard interfaces.

All these different requirements require a modular overall concept.

Besides its main task - maximising of energy production - the system has to support the operators in all different operating conditions (e.g. normal operation, flood and disturbances). At the same time the system has to contribute to the reduction of operation and maintenance costs.

On the basis of the existing infrastructure, an easy integration into the power plant's environment must be possible.

The Common Solution

Typical Tasks:

Power Plant Control

• head water level control
• discharge control
• power control
• reactive power control

Authority and Environmental Regulations

• downstream water flow limitation
• filling and discharging gradients
• level limitations
• flood alert

Forecast

• meteorological data (precipitation, temperature, snow depth, ...)
• calculation of incoming water quantities

Optimisation

• energy production
• reservoir utilisation
• swell operation of
• power plant cascades
• production scheduling

Interfaces

• equipment and maintenance
• database systems
• commercial database systems
• geographical information systems
• office packages

Marketing and Sales

• Internet (promotion)
• Intranet

Our Products

• SICAM 1703
  The SICAM 1703 Automation&Control system forms the platform for controlling of the power Generation process. State-of-the-art 32-Bit multi-processor technology is the powerful basis of centralised as well as decentralised control concepts. Optimised redundancy solutions assure highest availability of important process functions.

• 250 SCALA
  The 250 SCALA product family represents a full-featured modern SCADA-system for hydro power plants. By its modular design, it allows to integrate functions as prognosis, production scheduling, ....

• TOOLBOX II
  The TOOLBOX II product family provides most modern software tools for data management, system engineering and comprehensive system diagnosis, supporting the engineering and service staff.

• CAEx plus
  CAEx plus is a graphical PLC programming user interface, according to IEC 61131-3. CAEX plus is characterised by easy operation and user-friendliness.

• HyNET
  The HyNET product family is the basis of the safe communication. It interconnects all relevant components inside and outside of the plant. By usage of Ethernet technology, seamless connection to the Internet/Intranet is possible, allowing to implement new, powerful and cost-effective solutions.

• Software Application
  By consequent usage of international standards for system interfaces, various software applications (e.g. standard office packages or customer specific software) can be easily integrated.

3D TRASAR® Boiler Technology for Refineries and Petrochemical

Refineries and petrochemical plants have some of the most challenging boiler feed water systems, and boiler reliability is critical to plant operations. If a boiler is shut down unexpectedly, it can impact the on-stream availability of an entire process unit and result in reduced production.

Since changing conditions impact different parts of the boiler system...often very quickly...3D TRASAR Boiler Technology is critical. Nalco completes a thorough audit (mechanical, operational, and chemical) of your boiler systems in order to understand the gaps and make recommendations specific to your operational goals. This approach is designed to drive the results, reliability, and cost savings that all refineries and petrochemical plants expect.

3D TRASAR Boiler Technology

There are many different variables that can affect the total system performance of a steam system boiler including feed water quality, chemical treatment program, contamination events, and operational factors. These variables can cause system stresses that manifest themselves as operational problems: pre-boiler corrosion and economizer failures, boiler tube scale, boiler carryover, and fouling of critical downstream equipment such as turbines. 

The 3D TRASAR program detects system variations, then determines and delivers the correct program dosage. Nalco continues to improve the technology, making it the industry standard for monitoring and control that delivers measurable results. The technology can be customized and upgraded to ensure your system has the amount of desired control when you want it. It also has web accessibility and easy reporting capabilities in one, easy to install package. http://www.youtube.com/watch?v=uVEfU8x9A6I&feature=player_embedded

The Deliverables 3D TRASAR Boiler Automation delivers value by:

• Improving boiler reliability
• Optimizing energy and water usage
• Reducing green house gases
• Reducing the total cost of operations

The technology provides real time diagnostic capability, reduces scaling potential, reduces pre-boiler corrosion potential, and reduces carryover potential.

3D TRASAR Internal Treatment Control 

Nalco continues to improve tracing technology, making it the industry standard for monitoring and control that delivers measurable results. Boiler internal treatment control is achieved with various sensor technologies coupled with the most advanced boiler internal treatment chemistry. Upsets that could cause scaling or corrosive conditions automatically triggers control actions which brings the system back to safe parameters, maintaining clean boiler tubes 24 hours a day, 7 days a week.

3D TRASAR Pre-Boiler Corrosion Control 

The Nalco Corrosion Stress Monitor (NCSM) minimizes preboiler corrosion by measuring and reacting to the net oxidation/ reduction potential of the bulk feedwater, at the actual boiler operating temperatures and pressures. The NCSM detects changes in oxidation/reduction stress, determines the corrective action and responds in real-time by changing oxygen scavenger or metal passivator feed to protect the system. It is now possible to detect and react to the conditions inside the preboiler system under actual operating temperatures and pressures, allowing 3D TRASAR technology to deliver superior boiler system performance.

3D TRASAR Boiler Cycles Management 

Nalco’s 3D TRASAR Boiler Automation also helps optimize and control boiler blowdown. The outcome is increased heat efficiency, reduced energy requirements, increased water reuse, asset preservation, and improved utilization of fuel to heat your boiler.

3D TRASAR Information Management 

We offer a data driven process for continuous improvement. 3D TRASAR Boiler Technology continuously monitors key system parameters and KPIs which can then be analyzed from the convenience of your control room (DCS), on-line or by downloading to a laptop computer.

ROI Case Studies:

• 3D TRASAR Technology for Boilers reduces pre-boiler corrosion & unplanned boiler shut downs in a West Coast Refinery resulting in $4.8 MM in savings.
• Refinery improved sustainability, saving $372,000 per year in energy and water savings by optimizing boiler blowdown via 3D TRASAR boiler blowdown management.

Sensors take the heat

Greenwich University researchers are to work with Oxsensis on the development of sensors that can measure pressure and temperature at more than 1,000C.

Greenwich University researchers have won a SPARK award to work with Oxfordshire-based Oxsensis on the development of sensors that can simultaneously measure pressure and temperature at more than 1,000C.

Prof Chris Bailey, who leads the Computational Mechanics and Reliability Group in the School of Computer and Mathematical Sciences at the university, will use computer modelling techniques to predict how the sensors and their components would operate under different conditions of fluid flow, temperature and vibration.

The research will help Oxsensis with the design, assembly and installation of the sensors, which operate deep inside combustion engines.

Prof Bailey said: 'The aerospace and car manufacturing industries are demanding improved sensors because next-generation engines are getting much hotter. At the moment, no sensor can work reliably above 800 degrees.'

The two partners will start working together this month.

Oxsensis, which was formed in 2003 as a spin-out from Rutherford Appleton Laboratory, is developing sensor technology based on the micromachining of super-resistant materials such as single-crystal sapphire (melting point >2,000C) together with innovative fibre-optic interrogation techniques that give high sensitivity and immunity from electro-magnetic interference effects common in turbo-machinery such as gas turbines.

The SPARK awards, which started in 2002, are given to higher education institutions that help small and medium businesses tackle a problem of direct relevance to them. They also aim to encourage longer-term relationships between educational and business organisations.

The SPARK awards are organised by the Integrated Products Manufacturing Transfer Network, one of the Knowledge Transfer Networks of the Technology Strategy Board, jointly with the Innovative Electronics Manufacturing Research Centre (leMRC) of the Engineering and Physical Sciences Research Council.

http://www.omron.co.id/application_solutions/category_details.asp?app_id=E484

http://www.omron.co.id/application_solutions/category_details.asp?app_id=E484

ABC Formula/Conversion Table for Wastewater Treatment,Industrial, Collection and Laboratory Exams

A Methodology for Commissioning Control Loops

Several years ago our company recognized the need to integrate system commissioning into our construction process in order to consistently meet the owner and design team's needs and expectations. Below is a summary of the process we have developed by trial and error over the last 8 years.

1. Design Review: Review of drawings and specifications to verify the following: Coordination between trades; code compliance; equipment selection and capacities; control sequences for all equipment; and control system component specifications.

2. Submittal Review: Review of HVAC equipment and control system submittals to verify the following: equipment capacities, types and features; control system architecture; and control system component accuracies, ranges, signal types, ratings, and failure modes.

3. Commissioning Plan: Name and telephone number for all participants in commissioning process schedule of activities; HVAC pre-start and start-up checklists; analog device testing and calibration sheets; digital device testing and set point sheets; functional performance test sheets for all DDC control loops; testing and calibration procedures for all devices.

4. Equipment Start-up: 

A. Pre-Start Activities: Confirm device wired to the appropriate voltage source; heater elements installed in motor starter devices; shipping restraints removed; device rotates freely; adjust pulleys, belts, couplings; safety devices installed; and disconnect switches installed.

B. Start-Up Activities: Confirm that noise and vibration levels are acceptable; Confirm source voltage is acceptable all phases; record actual and rated amperage; and check device rotation

5. Critical Input Calibration: A. Analog Input Devices 

1. Temperature devices without transmitters (Thermistor, resistance type)

a. Disconnect sensing element from loop.

b. Check for failed signal at address.

c. If system shows failed continue to next step. If not, check for shorted wire or a bad software address.

d. Connect decade box or suitable resistance simulation device place of sensing element.

e. Simulate the resistance corresponding to zero, fifty, and one hundred percent of system design rating.

f. Adjust control system software offset or slope and intercept as required to ensure reading with in stated tolerance.

g. Replace sensor element. Make sure the system is receiving the correct signal.

2. Temperature devices with transmitters (RTD type)

a. Assemble required equipment: Decade box, digital VOM, trim screwdriver, and RTD resistance vs. temperature chart specific to the element being tested

b. Adjust the decade box setting so that the transmitter output is 4.00 mA.

c. Record the resistance value and the corresponding temperature.

d. Adjust the decade box setting so that the transmitter output is 20.00 mA.

e. Record the resistance value and the corresponding temperature.

f. Subtract the temperature in step b from the temperature in step c. This is the transmitter span. Adjust the transmitter span potentiometer as required to allow the actual span to match the required span. Repeat steps b and c to confirm.

g. Set the decade box to the resistance corresponding to a 4.00 mA output.

h. Adjust the zero potentiometer as required for the transmitter to produce a 4.00 mA out put signal.

3. Pressure Transmitters:

a. Disconnect the sensing element from the transmitter and replace it with a hand-held calibrated pressure simulation device with an accuracy that exceeds the rating of the transmitter to be calibrated.

b. Install a VOM meter in line with the negative terminal of the transmitter.

c. Determine the following values from the manufacturer's data:

(1) PMIN - Pressure at minimum transmitter output

(2) PMAX - Pressure at maximum transmitter output

(3) TMIN - Minimum transmitter output signal (mA or VDC)

(4) TMAX - Maximum transmitter output signal (mA or VDC)

d. Adjust the pressure until the transmitter output equals TMIN. This value is P1.

e. Adjust the pressure until the transmitter output equals TMAX. This value is P2.

f. Adjust the span potentiometer until the transmitter output signal equals the following:

g. Adjust the pressure to PMIN value.

h. Adjust the zero potentiometer until the transmitter output signal equals TMIN.

i. Adjust the pressure to [PMin - P Max / 2 ]  , and confirm that the transmitter output signal is equal to [TMin - T Max /2 ]  .

j. Repeat steps d) through i) as required.

4. Relative Humidity

a. Disconnect wire from negative terminal of transmitter.

b. Connect VOM between the sensor and the signal wire to read current (mA) of the device.

c. Using a hand held relative humidity calibration device, compare the output signal of the transmitter to the expected value.

d. Adjust the zero potentiometer of the transmitter as required so that the output matches the expected value.

5. Digital Inputs

a. Remove the control wiring and verify the control system address.

b. Alternatively open and close the control wiring circuit and confirm the corresponding change of state at the control panel.

c. Record the setpoints.

6. Output Calibration:

A. Analog Output Devices

1. Control valve (pump operational during test)

a. Disconnect control signal and record valve position.

b. Command valve to 0%, 25%, 50%, 75%, and 100% position and observe valve response. Adjust the control signal output device(s), including I/P transducer and/or pilot positions, as required.

2. Control Damper (fan operational during testing)

a. Disconnect control signal and record damper position.

b. Command damper to 0%, 25%, 50%, 75%, and 100% position and observe response. Adjust the control signal output device(s), including I/P transducer and/or pilot positions, as required.

3. Fan Speed Control

a. Disconnect control signal and record fan speed.

b. Command VSD to 0%, 25%, 50%, 75%, and 100% maximum speed and observe fan speed response.

B. Digital Output Devices 

1. Remove the control wire at the termination of the digital output wiring (relay, E/P, contract, starter, etc.) and verify address.

2. Alternatively command the output opened and closed from the control system, and confirm the appropriate response at the controlled device.

7. Functional Performance Testing: 

A. Overview: Functional performance testing is the method by which the control loop logic is tested for proper performance for each controlled system. This is accomplished by revising set points or simulating events and comparing the actual system response to the expected system response.

B. Normal control sequence: Perform a step-by-step test of all the various control logic sequences for each HVAC system by revising setpoints or simulating events (contact closure, etc.) and observing system response.

C. Safety interlocks: Verify that the following interlocks shut down the appropriate equipment when the equipment is operating in either the "hand," "automatic," or "local" control modes: fire alarm, duct detectors, manual safety switches, high or low temperature, and high or low pressure.

D. Overrides: Verify the proper system response to manual override devices, including occupant override switches, life safety override switches, control panel digital switches, and control panel analog output gradual switches.

E. Failure Modes: Remove the control signal and confirm proper position of the analog and digital control devices.

F. Loop Tuning: Upon completion of testing and prior to final acceptance testing, adjust the proportional, integral and derivative gains of each DDC control loop as required to provide stable operation.

8. Acceptance Testing: 

A. Upon completion of the functional performance testing, the operation of each control loop shall be demonstrated for the owner's representative(s).

B. The owner's representative(s) shall include the building engineer(s) assigned to operate this facility, as this test is the first step in owner training.

9. Owner Training: Upon completion of the owner's acceptance the owner's representative(s) and building engineer(s) will be trained in the proper operation of the HVAC system. When system commissioning is properly executed, we have found that warranty costs are virtually eliminated. These savings in warranty costs more than pays for the cost of commissioning. Most importantly, thorough system commissioning ensures a working building and adds value for our customers. This added value can differentiate you from your competition.

 

XCorr Corrosion sensors

Corrosion, in one form or another, can cause high value assets to deteriorate, shortening their useful lives. Corrosion related repairs and replacements drives up costs. Thus Condition Based Maintenance (CBM) strategies are being explored by many organizations in an effort to reduce inspection costs while minimizing the risk of equipment damage from corrosion. Aginova provides several tools to help in scheduling maintenance.

Coating degradation (CDS)

orrosion Protection Compounds (CPCs) or paints are routinely applied on military assets for prevention of corrosion. When exposed to the elements (water, light and salt) these coatings degrade and therefore have to be reapplied. Typically these are applied at fixed time intervals that can sometimes be too soon or too late. The CDS measures the coating degradation in terms of impedance (measured in ohms) and phase angle.
Therefore CDS can be used to determine the condition of the coating. The photograph above shows a sensor head developed by SwRI® which when coupled with the appropriate electronics measures the coating impedance. The photograph shows a complete packaged solution using CDS, T and RH.
SPECIFICATION
Impedance range* 100 ohms to 10 Mohms.
Phase angle 0 to -90.
Frequency range 100Hz to 105Hz.

Water detection (WLS)

Number of wetness cycles as well as the corrosivity of the environment can be measured using the IDS. The photograph to the left shows a corrosivity sensor where one of the electrodes is copper and the other is an iron-chrome alloy. A DC potential is applied across the two probe leads and a current response measured. The ratio of potential to current is inversely proportional to the corrosion.
When both electrodes are made out of the same material such as copper the sensor detects the presence of moisture and can be used to measure the number of wetness cycles. The sensor can be used to measure corrosivity or detect moisture. The IDS sensor in combination with Temperature and RH gives a better picture of the corrosivity of the environment.

SPECIFICATION
Fixed potential applied and resistance measured.
Resistance range – Two orders of magnitude.

Corrosivity measurement (MAS)

Multi Array Sensor probe is a passive electrochemical sensor where there is no applied voltage. As an immediate benefit, there are no issues associated with sensor control. It is a true corrosion rate monitor able to measure uniform and localized corrosion.
This MAS probe sensor is unique in that it does not rely on electrolyte solution to bridge the gap between the probe elements (although electrolyte must be present at anode and cathode sites). Each element is connected together through a common wire within the electronics package.
In this manner anodic (corrosion) and cathodic sites can develop at the elements as on an actual metal. A typical circuit to measure the low currents is shown in the figure to the left. Note MAS probe is the only sensor in the market that can measure pitting corrosion.

Damage Assessment (DAS)

Damage Assessment Sensor (DAS) is perhaps the simplest of all, and requires the monitoring of a property that is related to the volume of material present. It is similar to an ER probe, a coupon like specimen is utilized, but this specimen is position where the resistance to current passing through the coupon is measured (typically a wire).
As the wire corrodes, it’s conductor cross sectional area decreases, causing the resistance to rise. This elevation in resistance can be tracked over time to yield corrosion rate. ER probes are sensitive to other factors which influence resistance (Temperature), and must therefore be accounted for. Eventually, the wire coupon corrodes through and no current is passed. The damage assessment sensor builds in redundancy to the electrical resistance sensor by simultaneously monitoring a multitude of wires each with a different thickness. As the smaller diameter wires corrode through, a definitive “calibration point” is measured with which to check the crude measure of corrosion rate.
This sensor has been tested in the laboratory. Field trials are planned in Q4 2007. More details will be provided after the field trials.

Ultrasonic Wall Thickness measurement sensor

Aginova is developing a new generation of Wireless Wi-Fi® Ultrasonic Wall Thickness measurement sensors. The sensors can operate on a pipeline at up to 300°C in continuous operation (ambient temperature outside pipe).
It becomes now possible to:

• Continuously monitor thickness of pipes
• Suppress human intervention
• Access unreachable pipelines
• Get a correct picture of the pipelines corrosion state

OPC Overview

OPC (OLE for Process Control)

is a series of standards specifications. The first standard (originally called simply the OPC Specification and now called the Data Access Specification) resulted from the collaboration of a number of leading worldwide automation suppliers working in cooperation with Microsoft. Originally based on Microsoft's OLE COM (component object model) and DCOM (distributed component object model) technologies, the specification defined a standard set of objects, interfaces and methods for use in process control and manufacturing automation applications to facilitate interoperability. The COM/DCOM technologies provided the framework for software products to be developed. There are now hundreds of OPC Data Access servers and clients available.

Adding the OPC specification to Microsoft's OLE technology in Windows allowed standardization. Now the industrial devices' manufacturers could write the OPC DA Servers and the software (like Human Machine Interfaces  HMI ) could become OPC Clients. 

The benefit to the software suppliers was the ability to reduce their expenditures for connectivity and focus them on the core features of the software. For the users, the benefit was flexibility. They don't have to create and pay for a custom interface. OPC interface products are built once and reused many times, therefore, they undergo continuous quality control and improvement. 

The user's project cycle is shorter using standardized software components. And their cost is lower. These benefits are real and tangible. Because the OPC standards are based in turn upon computer industry standards, technical reliability is assured. 

The original specification standardized the acquisition of process data. It was quickly realized that communicating other types of data could benefit from standardization. Standards for Alarms & Events, Historical Data, and Batch data were launched. 

Current and emerging OPC Specifications include: 

Specification	Description
OPC Data Access	The originals! Used to move real-time data from PLCs, DCSs, and other control devices to HMIs and other display clients. The Data Access 3 specification is now a Release Candidate. It leverages earlier versions while improving the browsing capabilities and incorporating XML-DA Schema.
OPC Alarms & Events	Provides alarm and event notifications on demand (in contrast to the continuous data flow of Data Access). These include process alarms, operator actions, informational messages, and tracking/auditing messages.
OPC Batch	This specification carries the OPC philosophy to the specialized needs of batch processes. It provides interfaces for the exchange of equipment capabilities (corresponding to the S88.01 Physical Model) and current operating conditions.
OPC Data eXchange	This specification takes us from client/server to server-to-server with communication across Ethernet fieldbus networks. This provides multi-vendor interoperability! And adds remote configuration, diagnostic and monitoring/management services.
OPC Historical Data Access	Where OPC Data Access provides access to real-time, continually changing data, OPC Historical Data Access provides access to data already stored. From a simple serial data logging system to a complex SCADA system, historical archives can be retrieved in a uniform manner.
OPC Security	All the OPC servers provide information that is valuable to the enterprise and if improperly updated, could have significant consequences to plant processes. OPC Security specifies how to control client access to these servers in order to protect this sensitive information and to guard against unauthorized modification of process parameters.
OPC XML-DA	Provides flexible, consistent rules and formats for exposing plant floor data using XML, leveraging the work done by Microsoft and others on SOAP and Web Services.
OPC Complex Data	A companion specification to Data Access and XML-DA that allows servers to expose and describe more complicated data types such as binary structures and XML documents.
OPC Commands	A Working Group has been formed to develop a new set of interfaces that allow OPC clients and servers to identify, send and monitor control commands which execute on a device.

The DCOM Architecture

DCOM is an extension of the Component Object Model (COM). COM defines how components and their clients interact. This interaction is defined such that the client and the component can connect without the need of any intermediary system component. The client calls methods in the component without any overhead whatsoever.

Figure 1: COM components in the same process

In today's operating systems, processes are shielded from each other. A client that needs to communicate with a component in another process cannot call the component directly, but has to use some form of interprocess communication provided by the operating system. COM provides this communication in a completely transparent fashion: it intercepts calls from the client and forwards them to the component in another process.

Figure 2: COM components in different processes

When client and component reside on different machines, DCOM simply replaces the local interprocess communication with a network protocol. Neither the client nor the component is aware that the wire that connects them has just become a little longer.
Figure 3 shows the overall DCOM architecture: The COM run-time provides object-oriented services to clients and components and uses RPC and the security provider to generate standard network packets that conform to the DCOM wire-protocol standard.

Figure 3: DCOM: COM components on different machines

Components and Reuse

Most distributed applications are not developed from scratch and in a vacuum. Existing hardware infrastructure, existing software, and existing components, as well as existing tools, need to be integrated and leveraged to reduce development and deployment time and cost. DCOM directly and transparently takes advantage of any existing investment in COM components and tools. A huge market for off-the-shelf components makes it possible to reduce development time by integrating standardized solutions into a custom application. Many developers are familiar with COM and can easily apply their knowledge to DCOM-based distributed applications.

What is OPC Server Development?

An OPC Sever is a software application that acts as an API (Application Programming Interface) or protocol converter. An OPC  Server will connect to a device such as a PLC, DCS, RTU, etc or a data source such as a database, HMI, etc and translate the  data into a standard-based OPC format. OPC compliant applications such as an HMI, historian, spreadsheet, trending  application, etc can connect to the OPC Server and use it to read and write device data. An OPC Server is analogous to the  roll a printer driver plays to enable a computer to communicate with an ink jet printer. An OPC Server is based on a  Server/Client architecture.

There are many OPC Server Development toolkits available for developing your own OPC Server; MatrikonOPC's Rapid OPC Creation  Kit (ROCKit) is one of it and enables quick OPC Server development. ROCKit offers a flexible and affordable solution that  enables programmers to fully control their own product.

OPC ROCKit packages the complete OPC interface into a single DLL, eliminating the need to learn the complexities of Microsoft  COM, DCOM or ATL. A developer simply writes the communication protocol routines for the underlying device and ROCKit takes  care of the OPC issues.

Features include:

- Fully compliant with OPC DA 1.0a, 2.05 and 3.0 specifications.
- Free threading model on Windows NT, 2000 and XP platforms.
- Supports self-registration, browsing, data quality reporting, and timestamps.
- Can be used as a stand-alone server or as a service.
- In-proc server design for high-performance communication.
- Sample application code and comprehensive documentation illustrating how to use the ROCKit.
- OPC Explorer client that exercises the OPC COM interface for testing and debugging your server.
- The interface to the Device Specific Plug-in application code is separate from the OPC COM interface code. This means that  future OPC source code updates are simply plugged in, while your own protocol code remains untouched, resulting in minimal  engineering effort.

What are Realtime Operating Systems RTOS?

A real-time operating system (RTOS) is a class of operating system intended for real-time applications. Such applications include embedded (programmable thermostats, household appliance controllers, mobile telephones), industrial robots, spacecraft, industrial control (e.g. SCADA), and scientific research equipment.

A RTOS facilitates the creation of a real-time system, but does not guarantee the finished product will be real-time; this requires correct development of the software. A RTOS does not necessarily have high throughput; rather, a RTOS provides facilities which, if used properly, guarantee deadlines can be met generally ("soft real-time") or deterministically ("hard real-time"). A RTOS will typically use specialized scheduling algorithms in order to provide the real-time developer with the tools necessary to produce deterministic behavior in the final system. A RTOS is valued more for how quickly and/or predictably it can respond to a particular event than for the given amount of work it can perform over time. Key factors in an RTOS are therefore minimal interrupt and thread switching latency.

A significant problem that multitasking systems must address is sharing data and hardware resources among multiple tasks. It is usually "unsafe" for two tasks to access the same specific data or hardware resource simultaneously. ("Unsafe" means the results are inconsistent or unpredictable, particularly when one task is in the midst of changing a data collection. The view by another task is best done either before any change begins, or after changes are completely finished.)

General-purpose operating systems usually do not allow user programs to mask (disable) interrupts, because the user program could control the CPU for as long as it wished. Modern CPUs make the interrupt disable control bit (or instruction) inaccessible in user mode to allow operating systems to prevent user tasks from doing this. Many embedded systems and RTOSs, however, allow the application itself to run in kernel mode for greater system call efficiency and also to permit the application to have greater control of the operating environment without requiring OS intervention.

What are Manufacturing Execution Systems?

A Manufacturing Execution System (MES) is system that companies can use to measure and control production activities with the aim of increasing productivity and improving quality.

A Manufacturing Execution System MES is a shop floor control system which includes either manual or automatic labor and production reporting as well as on-line inquiries and links to tasks that take place on the production floor. MES includes links to work orders, receipt of goods, shipping, quality control, maintenance, scheduling, and other related tasks.

The ISA has defined standards regarding the structuring of MES and its integration in a larger company-wide IT architecture. ISA-95 "Enterprise-Control System Integration" defines a layer model looking at the integration aspects between ERP, MES and the production control level. It is supported by several vendors in the MES area. ISA-S88 "General and Site Recipe Models and Representation" defines a process state model for the batch industry.

What is CMMS Software?

Computerized maintenance management system (CMMS) software and enterprise asset management (EAM) software is used to manage  maintenance operations on capital equipment and other assets and properties. CMMS software and EAM software helps maintenance  personnel and departmental managers make better decisions for the allocation, maintenance, scheduling and disposal of  equipment and properties.

Computerized maintenance management software includes features such as work order generation, event logs, scheduling of  preventive maintenance checks and services, and downtime analysis. CMMS software also allows users to plan equipment  maintenance activities to coincide with the schedules of employees such as technicians, mechanics, and operators. Maintenance  management reporting may also be included. CMMS software can be industry-specific or designed for a range of industries such  as transportation, energy and utilities, manufacturing, engineering, and automation.

Enterprise asset management software is designed to improve operational productivity and processes, and track, manage, and  extend the life of critical assets. With EAM software, corporate managers and executives can monitor the status of plants,  buildings and facilities or develop a plan for inventory control. EAM software features include modules to define assets,  track asset usage, maintain asset documents (i.e., warranties, lease agreements, and contracts), and flag assets for  maintenance or other event triggers.

The strongest feature set of CMMS software and EAM software is the ability to integrate the two products into a single  maintenance and management solution. Such integration permits more efficient interaction between various departments within  an organization. For example, when an asset is reported as damaged, service requests can be entered into the system and an  alert immediately sent to maintenance personnel. Mechanics or engineers can then inspect the asset, open work orders, and  alert purchasing agents of any need for the procurement of parts, tools, or other materials to perform repairs. Managers can  run regular reports to identify areas of repeated failure or those assets that cost the most to retain and repair. This  permits the proper distribution of budgeted funds, or implementation of better maintenance and management processes.