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ISA100 Newsletter - 2nd Quarter 2009

In this issue:

ISA100 and ISA99 Standards Included in the EPRI Interim Report on the Smart Grid Interoperability Standards Roadmap for NIST

The ISA100 Wireless Systems for Automation, the emerging standard for industrial wireless, and ISA99 Manufacturing and Control Systems Security Standard have been identified for use in the Smart Grid Interoperability Standards Roadmap for the National Institute of Standards and Technology (NIST) by Electric Power Research Institute (EPRI). This recognition is a result of Automation Federation efforts to drive home the message that automation standards and automation professionals are vital to the future of Smart Grid.

Under the Energy Independence and Security Act (EISA) of 2007, NIST has "primary responsibility to coordinate development of a framework that includes protocols and model standards for information management to achieve interoperability of smart grid devices and systems..." As a result, NIST awarded EPRI a contract to engage Smart Grid stakeholders and develop a draft interim standards roadmap. In addition, NIST has hosted a year-long planning effort to develop the Smart Grid interoperability framework—an effort in which the Automation Federation has taken part.

Through active engagement in NIST Domain Expert Working Group (DEWG) activities, EPRI led workshops, and other industry planning activities, Automation Federation representatives have stressed the importance of the use of recognized standards like ISA99 and ISA100 and the involvement of automation professionals in the successful implementation of Smart Grid. To learn more about ISA99, visit www.isa99.org; ISA100, www.isa100.org; and other ISA developed standards, www.isa.org/standards.

EPRI defines Smart Grid, in their report, as "a modernization of the electricity delivery system so it monitors, protects, and automatically optimizes the operation of its interconnected elements—from the central and distributed generator through the high-voltage network and distribution system, to industrial users and building automation systems, to energy storage installations, and to end-use consumers and their thermostats, electric vehicles, appliances, and other household devices."

This definition lends strength to the Automation Federation's efforts to ensure the use of internationally recognized standards, like those developed by ISA, and the vital involvement of automation professionals to the success of the Smart Grid framework development, implementation, and maintenance.

NIST will review the comments received in this interim report from EPRI, including the comments on the use of these ISA standards. The Automation Federation will continue to engage in the framework development process to ensure that appropriate standards are included in the final framework that will be adopted by NIST. Read the report, developed and delivered to NIST by EPRI, at http://www.nist.gov/smartgrid/.

Leo Staples, Automation Federation energy committee chair, said, "I am pleased that EPRI recognizes the value of incorporating ISA standards into the NIST Smart Grid framework. We will continue to work through the process to ensure that appropriate standards, including these ISA standards, are a part of the final framework."

Wireless networking in plant

The advantages of a mesh network are redundancy, increased total distance, and removal of the line-of-sight restriction

By Dick Caro

The reduced cost of Ethernet-based networks is driving this fast, low-level, and low-cost technology to the field and shop floor.

Another Ethernet side effect is the application of wireless technology in the Wi-Fi group of wireless protocols. Wi-Fi is essentially wireless Ethernet. Any higher-level application layer and user layer can communicate via Wi-Fi at data rates up to 600 Mbps, without knowledge of the fact that it is on a radio link.

Wi-Fi is the most common wireless technology in 2008; however, it has significant problems for operation in the electrically noisy environment of a process plant or the shop floor in a manufacturing factory.

The popular Wi-Fi-a/b/g standards can achieve a theoretical maximum of 54 Mbps using one of the 2.4 GHz channels. However, the not yet finalized Wi-Fi-n standard, which has a maximum rated specification of 600 MHz, is even more interesting.

Wi-Fi-n allows the bonding of several radio channels, including the channels in the 5 GHz, band to achieve its high speed, but is not due to be finalized until the end of 2009.

The feature of Wi-Fi-n that is most appealing to industrial use is its adoption of multiple input, multiple output (MIMO) technology. MIMO has the demonstrated potential to eliminate the adverse effects of reflections that cause multipath distortion appearing as signal fade. MIMO achieves improved reception through detecting the multipath signals and either eliminating them or phase shifting them to amplify the received signal.

Early experiments suggest using Wi-Fi-n can achieve excellent behavior in both process plants and factories notorious for their "canyons of steel," the cause of poor performance of Wi-Fi-a/b/g.

Both commercial and industrial versions of "pre-N" devices are already widely being sold. Of course, use of wireless technology brings problems of security and privacy to industrial networks, which was never much of an issue before.

HART to handheld terminal

Wireless technology provides excellent solutions to the problem of the high cost of industrial wiring and also provides an ultimate barrier to electrical surges introduced to field equipment through field wiring.

The cost of these wireless advantages is the difficulty of supplying power to field devices, which previously got power from the same cable used to conduct the data exchange between the field device and a host system.

Although there were a few wireless field sensors offered for sale in 2008, it is likely the potential cost reduction of avoiding wire/cable installation and maintenance will provide an expanding market for wireless sensors in the future. Additionally, users are always finding new applications for industrial measurements and controls that leverage wireless devices. These applications were often not economic when they required wired connection.

By the end of 2008, a few WirelessHART process field transmitters were available commercially. In addition, a simple device to convert wired HART transmitters and valve positioners to the WirelessHART protocol is available.

WirelessHART is a de facto standard supported by the HART Communications Foundation, and it is an IEC PAS (publicly available specification). An IEC working group to develop an international standard for WirelessHART has approval.

WirelessHART uses the IEEE 802.15.4:2006 standard modified to hop among the 15 or 16 frequencies (channels) specified by that standard in the 2.4 GHz ISM (industrial, scientific, and medical) band. The slot time is constant for the entire network, usually 10 ms. Transmission encrypts via a 128-bit key to achieve a high degree of security.

Field devices are all part of a mesh network with a secure method of building and repairing the mesh. The advantages of a mesh network are redundancy, increased total distance, and removal of the line-of-sight restriction.

A simple transport layer ensures end-to-end message delivery and confirmation when required. Like wired HART, HART commands poll data access, including all maintenance functions of the WirelessHART network. WirelessHART devices may also be set to transmit data using a publishing method. WirelessHART devices are provisioned (network setup) through a wired connection.

WirelessHART came to the fore as a simple wireless network for field instrumentation, and to enable a wireless method to access diagnostic data in HART instruments installed in the past.

There are probably more than 25 million of these HART instruments that can only provide their digital diagnostic data to a hand-held terminal, since the control systems to which they are connected cannot access that data over the connecting 4-20mA wire. WirelessHART is an answer to this problem.

Standardization for wireless

The ISA100 standards committee has been developing a comprehensive standard for industrial wireless communications. The first release from this organization is ISA100.11a, intended for process data acquisition and limited control needs in the process industries.

While the ISA100.11a standard has achieved ISA and ANSI standard status, it has not yet passed international (IEC) standardization. The fact that WirelessHART and ISA100.11a address the same market is apparent to many users, and the IEC has taken heed as well.

They are technically similar, but very different in detail, causing many users to request the standardization people to merge them. ISA100.12 is already in business to achieve convergence between WirelessHART and the ISA100.11a specification.

At press time, the standardization path for wireless process control and factory automation networks was not yet final. Resolution between WirelessHART and ISA100.11a may finish in 2009, but standardization is still unresolved.

ISA100.11a also uses the same IEEE 802.15.4:2006 standard in a way similar to that of WirelessHART by hopping among the 15 or 16 channels in the 2.4 GHz ISM band. ISA100.11a has far more options to adapt its network for a wide variety of applications including segmentation of the network and peer-to-peer messaging.

Unlike WirelessHART, each network segment may use a different hopping pattern and its own allocated time slot, which allows large networks to form where segments may overlap.

The definition of field routers reduces the number of hops required to reach the host device, and to bridge geographically separated network segments.

ISA100.11a also uses mesh networking, but allows devices at the edge of the network to not route messages for other devices. This can increase security by preventing unauthorized devices to access plant networks from outside the plant. It can also reduce the cost of devices by making them simpler. Additionally, ISA100.11a uses Internet-conforming IP addressing to make data from field devices addressable remotely.

The Transport Layer implements secure end-to-end message delivery, and confirmation uses Internet-conforming User Datagram Protocol messages.

Upgradeable to ISA standard

The Application Layer of ISA100.11a is completely object-oriented, in which data in field devices can be addressed using IEC 61804 standard EDDL protocol. For networks not using this standard, one may encapsulate and tunnel messages to the requesting host device.

ISA100 has already agreed to extend its work in several ways:

  • New physical layers (chip technology)
  • A wireless or wired backbone (backhaul) network
  • Factory-automation sensor network applications
  • High security or trustworthy applications
  • RFID and location-based services

ZigBee is an organization specifying additional higher layer protocols to use the same wireless IEEE standard, numbered 802.15.4. It can, by design, operate on the shop floor and avoid interference with Wi-Fi. It is also low cost, requires little power, and can transport Ethernet messages. Although ZigBee may operate with a star topology like Wi-Fi, it also allows operation in a mesh network topology.

By the time of our next report on the technology, we should have a much clearer picture of future industrial automation networks. Wireless offers too many advantages to ignore and will tend to change all of the existing networks we know so well to "legacy" status.

However, you cannot install standard wireless networks today, but you may purchase WirelessHART devices and other devices that claim to be upgradable to the ISA100.11a standard.

Wireless networks of any kind do not yet exist for factory automation sensors.

ISA100 Committee meets in Luton, England

The ISA100 committee held a series of meetings at the MTL Instruments facility in Luton, England, July 28-30. The ISA100 committee is composed of many subgroups chartered to address the unique challenges of implementing wireless technology in difficult industrial environments. Several of the subgroups met in Luton, including those focused on co-existence and interoperability of industrial wireless systems, wireless backhaul, industrial wireless security, factory automation, and convergence methods with other wireless specifications.

The next major meetings of ISA100 and its subgroups will be in conjunction with ISA EXPO 2009 in Houston, Texas, during the week of October 5. For information, visit www.isa.org/flm.

Working Group Spotlight: Factory Automation

The ISA100 Factory Automation Working Group (WG16) was formed with the mission to investigate applications for wireless technology in the factory automation and discrete manufacturing industries such as automotive manufacturing, packaging machinery, machining, and robotics. Its first deliverable in support of that mission is the Technical Requirements for Factory Automation document, on which, it is making good progress.

The group is documenting, in clear terms, the various wireless communication attributes that are pertinent to Factory Automation, and then assigning specific quantifiable measures or ranges to the attributes. Through a formal Request for Proposal process, the Working Group is evaluating various technologies to better understand the process the proposers used, to better define their solution, and to ultimately make for a better Requirements Document.

An example of the attributes that are being considered in the Technical Requirements Document are Factory Automation topologies, performance under various use cases, power sources, time management and synchronization, security, coexistence and interference, environmentals, and other pertinent measures. The group expects to leverage the excellent work performed by their colleagues who worked on the ISA100.11a draft standard.