Tools in the DCS

Reliability and safety in the manufacturing process of the DCS. In addition to industrial control systems of the specific installation tools that are reliable, then. The design must also consider safety and limit the loss of production from various accidents or errors within the limited scope of most.


Control system to limit damage caused by defects or failure of K Engineering to hand within the limit.
Control systems to provide backup for control Vice hand control staff are able to control the manufacturing process to replace the main control section that has been able to do damage to normal soon.
Control system must provide protection system that pungent, Chen M for control staff can be ordered to stop and cancel all or part of the production process immediately all safety procedures.
Control system must be self-monitoring system for checking the accuracy of the operation was.

DCS increased the Church’s message holds and safety performance of industrial process control as follows.

Distribution of access equipment and process control of the DCS group were sub-divided the responsibility to monitor and supervise the manufacturing process of industrial indoor keeping the reliability of control systems are increasingly included.

Storage and backup program for performance instead of process control unit of the DCS by the fact type of sleep per Tile Wall internal memory storage of the program will function.

Installation provision for control instead of performance and process control unit connected to the process and the damage can not function normally. Tool control is acting.

Check the DCS system to check the performance of the tools within the system control and monitoring of contact with other tools connected to the DCS to perform with the accuracy at all times. Self-inspection system, and DCS has also instructed the alternate control tools that can come if DCS duty to replace the main control the damage as soon as detected. Disorders of the tool. The process can be carried out successfully with from time to time.

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Architecture DCS

DCS architecture of each manufacturing company may have different structures according to the design of each manufacturer’s production company, but DCS all companies have to share equipment in the DCS of a functional and operational responsibilities are Engine unit (module) always consists of the DCS Although each manufacturer has a different name, but must consist of DCS units are similar tools.

1. Unit connected to the process (process interface module) is a device interface between DCS and process to receive the signal measured by the production process to the DCS and control signals from the DCS to the manufacturing process. Processing units connected to basic unit consists of DCS analog input (analog input module) unit analog output (analog output module) unit digital signal (digital input module) and digital transmission unit (digital output module).

2. Unit process (process control module) is the main equipment of DCS for process control. By the data processing unit connected to the process to calculate the value of the control signal and send it back to the process units connected to process control unit connected again to contact the unit processes, process control networks. DCS sub-low speed control of the basic process consists of the DCS control and direct digital control stick and fire.

3. Unit Contact and staff functions (operator interface module) and the Laboratory of Engineers (engineerint workstation) is a device interface between DCS and power users, engineers and general staff DCS may spin contact and enter Ki Operation of employees and Engineering is the second set of equipment or devices sharing a single set of contacts and act as a unit’s operating staff and engineers. Unit contacts and skills last year’s Operation staff serves as staff, equipment Nื contact for monitoring and process control. Unit Ki Operating Engineers serves as the DCS equipment fitted to the Engineer for the structure of control systems and equipment connected to the DCS system. Of the details and the order of the graphics for the employees. Shows the trend of record-keeping process history. And warning events of DCS.

4. Unit connected to the network. (Communication module) device is a device for connecting all parts of the DCS network communication. Unit connected to the network initially will link DCS process control equipment with equipment and laboratory staff to contact.

5. Storage and historical processes (process data and history module) as storage devices for process control of the DCS and the history of the process data storage and historical process of the DCS are often installed with the unit interface and operation of employees and engineers. However, DCS may be separate storage devices, and historical processes are independent devices connected to their network communications. Storage devices include basic DCS Nื types of magnetic data storage (magnetic disk) and magnetic tape (magnetic tape).

6. Unit connected to a computer network (computer network interface module) is a device connected to the network of the DCS network of other computers for data collection and management control system, DCS can connect to a computer outside the system DCS. The devices use a Nื contact and connection of the unit’s operating staff and engineers. Or connect directly by the DCS network devices connected to computer networks.

7. Unit connected to the instrumentation sub (subsystem interface module) is a device connected to the DCS tool in an external control system, DCS, such as PLC, gas chromatography graph (gas chromatograph) devices to send and receive data remotely. (remote input / output device) and other tools to control the processor’s own DCS can interact with other tools in the control system via the network sub-unit connected to the process, or connected to the network communication of the DCS directly using sub-unit connectivity tools, as well as connect to other network computers.

8. The power unit (power supply module) is equipped with the power to all devices of the power of the DCS equipment. Served eliminate noise and adjust the power off to suit various devices of DCS and store energy reserves for DCS.

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What is DCS?

DCS (distributed control system) which comes from the DCS Distributed Control System includes the main control section, which is similar to the PLC, but bigger talent than Either control, Batch, Sequencial, Analog Control and Advance Contol and user interface which is similar to Scada, including the history, History, and other stores.

Because the control system in the first session will be used as a control Relay system. But soon evolved into PLC by language programming of PLC, it has all five languages: Ladder (LD), Instruction List (IL), Sequence Function Chart (SFC), Structure Text (ST) and Function Block Diagram. (FBD) to operate through a graphic that PLC will be connected to other devices is the MMI (Man Machine Interface) or sometimes referred to as HMI (Human Machine Interface), which in the PLC, most will not have built-in by the HMI. can display the value and status of the process and can Operate HMI, which is in part to show the important Historical Report, Alarm Message, Trend.

DCS is a system that evolved after the PLC will be the language used to write different. Depending on the brand. While there are some basic PLC logic in actual use in controlling large the process relatively static (such as process oil and gas) it is more stable than, and DCS will include Graphic, Trend, Historical, Alarm Message. included in the self.

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The IIntelligent Motor Control Centers (MCCs)

Advances in MCC technology enable the delivery of detailed diagnostics to help improve productivity and maximise asset availability. A new white paper, produced by Rockwell Automation, explains how advanced intelligent motor control centers (MCCs) provide process application users with critical information that ultimately helps minimise and prevent downtime

The white paper outlines industry drivers and the evolution of MCCs, including technology considerations, configuration methods, networking advantages, as well as benefits gained from real-world application examples. It describes the technology behind these capabilities, including advanced monitoring and sensing devices, and built-in network connectivity that allows access to process data from virtually every corner of the plant.

Distinguishing itself from a standard unit, the intelligent MCC integrates three major system components – communications, hardware and software. While early versions of MCCs with communication networks contained variations of these elements, today’s solutions leverage a harmonised design that deliberately integrates these elements into a unified solution.

Furthermore, with a lower installation cost than traditional MCCs, plus the protective, monitoring and troubleshooting advantages, integrating intelligent MCCs presents a major opportunity for manufacturers to capture and use equipment and process data to improve productivity and maximise asset availability.


For a copy of the white paper go to: http://samplecode.rockwellautomation.com/idc/groups/literature/documents/wp/mcc-wp001_-en-p.pdf

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Conventional Motor Control Centres (MCCs)

Conventional low-voltage Motor Control Centres (MCCs) are ubiquitous in the oil and gas sector and in general, meet industry requirements for safe, reliable and efficient operation. So, are there any real benefits to be gained by choosing the new generation of Intelligent Motor Control Systems (IMCSs) for future projects? The answer is undoubtedly yes except, perhaps, for the most undemanding of projects.

In a conventional MCC, the power switching and protection components that make up the individual starters are linked to the device that provides the control functions – most often a PLC, with conventional cabling. In addition, the functionality of the components used, such as the protection devices, is defined within those devices. If additional information is required from the starters as an aid to managing the plant or for measuring and controlling energy usage, extra components have to be added, along with even more cabling to the PLC.

In an IMCS the power switching devices are controlled by a Smart Control Unit (SCU) that also monitors the motor operating parameters, such as voltage and current. The protection functions are implemented in the SCU, which communicates with the PLC via a data connection, eliminating much of the conventional control system cabling, replacing it with just a handful of network cables.

Also, because the protection functions of the starter are now defined by software in the SCU, decisions about these functions do not need to be finalised until after the motor control system has been built. This is a useful feature in oil and gas applications, where late changes to plant configurations and specifications are common.

The functionality of the starters in the IMCS can also be changed easily and quickly even after the plant has been put into service, providing flexibility. Finally, since the SCU directly monitors the operation of the motor and the starter, it can provide almost any operational data needed for plant management, energy reduction or maintenance purposes directly, without the need to install additional equipment.

There are, however, still those who have reservations about the adoption of IMSCs There are essentially two reasons for this. The first is that some of the earliest IMCS implementations were ill-conceived and failed to deliver on their promises. These issues have now been addressed – the technology has matured.

The second is that there are some applications where conventional MCCs are still the best option, though these are reducing in numbers. Typical of these are simple installations where there is no requirement to collect data for onward transmission to a supervisory system and where the likelihood of modifications being needed during the life of the equipment is small. In such cases, a conventional MCC may well be adequate.

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Integrated Safety And Regulatory Control

Addressing functional safety and regulatory control in a single system has been a challenge for many years – even more so when systems are destined for use in a hazardous area.

A technical solution from Siemens is said to offer these combined capabilities delivering benefits such as a simplified safety verification process, tangible cost savings and scalability Ian Curtis, safety consultant for Siemens Industry Automation, explains.

The functional safety and hazardous area protection world’s are often closely associated. However, when it comes to meeting the requirements of these two complementary yet distinct disciplines in a distributed I/O system, there are many technical challenges to overcome.

A range of SIL 3 capable failsafe I/O modules for the Siemens ET200iSP hazardous area remote I/O station gives users the potential for new safety system architectures which boast simplified engineering and a reduction in the total lifecycle cost for automation and safety.

Early process automation systems were typically distributed but, ironically, with the advent of the Distributed Control System (DCS), system architectures actually became much more centralised. In recent years, there has been a shift back toward a more distributed approach. This same trend has been reflected, albeit to a lesser extent, in distributed safety within the process industry but the recent addition of capability for integrated failsafe I/O in the hazardous area looks set to accelerate this trend.

Given the conservative nature of the industry there are still many users who prefer to stick to a centralised approach, particularly when intrinsic safety requirements are involved. The traditional practice of putting the controllers and I/O in the safe area and using IS barriers, is well understood and still in common use. However the tough economic climate of the last few years has increasingly prompted end users and OEMs to assess and adopt new concepts such as distributed failsafe systems which can actually solve many problems.

The scalability of these distributed systems, particularly those that combine control and safety in the same infrastructure, means they can also be used cost effectively for small process units, OEM skids or rotating equipment with smaller I/O counts.

The distributed approach reduces the need for multi-core cables carrying I/O signals; this means reduced installation effort; reduced risk of wiring errors and simplified bus connection of I/O stations.

SIL3 capability in a Zone 1 hazardous area is a step change that will strengthen the success of distributed I/O systems and really open up new possibilities. Users from the oil and gas industry, chemical industry, and other major hazard industries will look to benefit from the ability to combine configurations that include non-fail-safe modules, such as standard inputs/outputs and relay modules, alongside failsafe modules. Another key benefit is the potential for cost saving through the elimination the ex-barriers, less wiring and space optimisation.

Many OEM suppliers are also exploiting the possibilities of distributed automation in hazardous areas, particularly when they market their products to target emerging markets. If the end customer's employees lack expertise, the use of a centralised configuration often leads to wiring errors - and a lengthy commissioning phase.

When the ET200 iSP remote I/O station is located directly at the machine, or process skid, commissioning is straightforward and the space savings are considerable. As complicated and space-consuming as the earlier approach was – with remote I/O cables, terminals, and ex-barriers – this marshalling effort can now be completely eliminated. It is also easier to achieve the redundancy required in many applications: The ET 200iSP is connected via RS485-iS in hazardous areas. The path from the CPU in the control room to the field can also be redundant. Digital and high availability requirements are covered thanks to bus use.

Because of an increasing popularity with the OEM market, if an end user doesn't start out with distributed safety as a strategy for their plant they often “inherit” it as process skids and OEM type equipment come equipped with their own safety systems.

The first large customers for the ET200 iSP F-modules have been from the oil and gas industry. They have used the fail-safe modules in water-oil separating equipment and tank farms. Other early adopters have come from the chemical industry. Offshore projects generally also lend themselves to distributed safety and the combination of failsafe and hazardous area capability afforded by these new modules will be attractive for such applications.

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Wireless Level Switch

Emerson process Management reports that intelligence inside its switches are now also able to distinguish between material build-up on the fork and a high product level, reducing the need for inspection in the field. Electronic Device Description Language (EDDL) is used to enable the level switches to be configured and monitored from the same device management software as a plant’s other intelligent devices such as pressure and temperature transmitters.

Adding hardwired level switches into an existing plant can be costly due to the cost of laying and connecting new cabling, as well as possibly additional cable trays, system input cards, and system tag license costs.

Many tanks around the plant will not originally have been fitted with instrumentation connected to the control system. Similarly, coolant and lubricant level in various assets have not been monitored continuously. Using wireless technology this type of information can now be better utilised.

Wireless level switches overcome the limitations of hardwiring. They can communicate using the IEC 62591 (WirelessHART) protocol and can be deployed without running cable or using up spare wires and system input cards. Because there are no wiring connections to be made, commissioning is also easier.

A wireless level switch will share the same network infrastructure as other wireless transmitters, with information transmitted via the same gateway. One gateway can support up to 100 IEC 62591 transmitters. Once a gateway is in place, plant personnel can expand the network at will, enabling level switches to be installed on points previously not monitored by the control system, to enhance operation and worker safety.

Because IEC 62591 devices all use the same common application protocol, devices and gateways from different manufacturers should work together seamlessly, self-organising to form a mesh network where each device maintains communication with multiple neighbours – establishing multiple communication paths and relaying data even from the most remote devices all the way to the gateway. If devices are added or removed, the network is able to automatically adjust its communication path, without interrupting data flow.

Modern DCS will have native support for wireless. However, older control systems can also make use of wireless level switches, or other IEC 62591 transmitters, using a wireless gateway that converts the signal to Modbus/RTU, Modbus/TCP, or OPC. Wireless support on the control system engineering console is not required as the network setup is done through a web server embedded in the gateway and devices are configured through intelligent device management software. No additional software needs to be loaded onto the control system or other PC for operations or security. All that is required are the existing HART configuration tools, including asset managers and hand-held configurators, to bring the network online.

A vibrating fork level switch operates on the principle of a tuning fork. An internal piezo-electric crystal oscillates the external fork at its natural frequency. The frequency changes depending on the medium in which it is immersed and these changes can be monitored. Unlike many other level switch technologies, the vibrating fork technology does not have parts that can get stuck and therefore is less prone to failure.

With a simple on/off signal from a hardwired float level switch it was not possible to tell the difference between a stuck switch and an actual high-level condition. Similarly, it was not possible to tell if the level switch was damaged or had failed and the signal was therefore invalid. For this reason, technicians are periodically required to go to the field to perform checks just to be sure, often to find nothing wrong.

With intelligent devices, however, changes in frequency are used to detect high or low level, as well as media build-up on the fork, external damage to the fork, internal damage to the piezo, and excessive corrosion.

Having such intelligence in the field can reduce the necessary trips to the field for inspection purposes, as many suspected problems can be remotely verified from the control room, and cleaning or service scheduled accordingly.

Remote set up
Remote setup is a relatively new development in level switches. Manufacturers can now use EDDL to define how a device is to be displayed in the system. This technology is used for continuous devices such as transmitters and positioners as well as with discrete devices such as level switches, on/off valves, and electric actuators.

The use of EDDL enables IEC 62591 level switches to be set up and checked using the same intelligent device management software as the other devices in the plant. The information from level switches can be displayed side-by-side with information from wireless transmitters for pressure, temperature, and other process parameters. They are displayed the same way as FOUNDATION fieldbus and PROFIBUS devices.

Systems based on EDDL are said to make managing the mix of devices easier, eliminating the errors and learning curve associated with using different software or different driver for each one. Manufacturer know-how, in the form of text and illustrations, is brought into the system through the EDDL file.

A device overview page will clearly indicate the process state as ‘wet’ or ‘dry’ and this is accompanied by device health status, which will indicate the validity of the information. Because the operator is able to tell the difference between media build-up on the fork and an actual high level they can act accordingly.

Material build-upon the fork can be detected in its early stages and flagged as an advisory alarm, so that cleaning can be scheduled before build-up accumulates to the point where it causes a false process state indication. As a supporting troubleshooting tool, the fork’s frequency is also displayed as a dynamic needle gauge with a colour band on the scale to distinguish normal from abnormal operation. The health of the internal power module is also indicated.

EDDL is key to interoperability, providing complete access to all device functionality through a hierarchical menu structure. The EDDL file from the device manufacturer is copied onto the system to tell it how to interface with the device. Unlike other device integration technologies, no software installation skills or license key management are required.

Each version of each device from every manufacturer has a unique EDDL file. There are no shared files, ensuring that the addition of a new device will not overwrite another. Because EDDL is a compressed text file, independent of the Windows operating system, existing device files are not made obsolete by new Windows versions. Conversely, new device files do not force a Windows upgrade for the system.

Time delay can be configured to minimise false switching due to turbulence or splashing, such as in the presence of agitators. To set the delay time on traditional level switches they must be opened up and a potentiometer adjusted by screwdriver. This is inconvenient in the field and exposes electronics to potentially harsh environments. With a WirelessHART vibrating fork level switch, the delay time and other settings can be checked and adjusted remotely from the control room, with the EDDL technology enabling the device management software to maintain a single audit trail for all devices, including level switches where configuration changes are logged.

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