Emerson Process Experts

When I posted last week on WirelessHART reliability, I had a chance to speak to Emerson's Russ Muller who is a senior PlantWeb specialist. As we discussed the reliability figures, Russ mentioned that the sites that applied the best practices saw reliability figures much higher than 99%. If you've seen the PlantWeb University Wireless course, in the Wireless 203- Self Organizing Networks section, it shows this figure:

Even in this extreme example of low reliability links, by designing multiple paths for each device, a self-organizing network can reach that level of performance by constantly choosing the path that offers the best reliability at the time. With self-organizing networks, it's important to note that site surveys are not required. Russ shared with me some best practices learned from the early wireless installations which I'll pass along to you.

The first consideration is the size of your facility. If you have a large facility like a refinery or chemical plant, the wireless field network should be scoped to a single process unit. For vertically arranged facilities like power plants or some pharmaceutical sites, the self-organizing network should be scoped to a single floor.

Next, it is extremely helpful to have a scaled drawing of the single process unit or floor where the network will be installed. In an earlier post, I discussed the creative use of Google Earth to zoom in on an outdoor facility where they didn't have scaled drawings handy. These building drawings are typically available for inside facilities, which is a good thing since the satellite photos can't see inside a building… yet!

With the scaled drawing, plot the location of wireless devices. Consider the immediate ones you want to install as well as possible future ones. Every wireless device should have multiple neighbors to provide path redundancy for higher overall communications reliability. Based on the experience gathered from hundreds of installations to date, each wireless self-organizing network should be designed with a minimum of five wireless devices to provide this path diversity.

As you look at the devices plotted on your scaled drawing, it's ideal that each device have three neighbors as potential paths of communication.

Next, consider the placement of the wireless gateway. In small networks, the smart wireless gateway should be located in the center of the network. For larger networks or installations that require the wireless gateway mounted in a control or rack room, you should build the self-organizing network around the location of the wireless gateway, closest ones first, per your plot plan. Also, remember that the gateway needs to connect the network to your host automation or asset management system using common industry communications standards like OPC, MODBUS and MODBUS TCP.

The wireless gateway should have a direct wireless connection (connected without a hop through another device) to 25% of the devices in the self-organizing network. It will still be reliable if less than 25%, but greater than 25% is optimal. You can add wireless devices or repeaters to help achieve this best practice.

During installation, add devices outward from the gateway to reach other areas in the process unit. This installation process helps you see the devices as they are being added and helps verify the robustness of the communications.

I hope sharing these best practices in addition to the PlantWeb University Wireless courses provides you the background to try a wireless field network application in your facility.

Tags: WirelessHART | self-organizing networks | mesh networks | scaled drawing | wireless gateway | OPC | MODBUS | MODBUS TCP |

June 17, 2008 in Education, in Interoperability, in Wireless | Comments (0)

I received a sneak peak of a white paper in the works by Dr. José Gutierrez, corporate director of technology with Emerson. This paper, based on the Why WirelessHART? article, discusses diversity techniques to achieve the reliability design objectives in the WirelessHART standard.

José begins with some history of proprietary point-to-point wireless "cable replacement" solutions. Data transmission was required for these applications but cables were not economically feasible to install. These wireless solutions also typically were not designed to scale.

Process manufacturers have been under constant market pressure to improve efficiency and productivity. This pressure has spurred innovations by automation suppliers on numerous fronts including advanced diagnostic algorithms, improved sensor technologies and improved communications technologies especially in the area of wireless communications.

In the 1990s, the U.S. Defense department invested in wireless communications research with high reliability, highly secure and extremely low powered design objectives. This basic research fed into future developments by leading industrial and technology companies on the IEEE 802.15.4 radio-communications standard for wireless sensor and actuator applications. José served as chief technical editor of the IEEE 802.15.4 standard.

During this time in 2003, the HART Communications Foundation started its wireless efforts that culminated in the release of the WirelessHART standard in the fall of 2007. This standard is designed to support a range of applications including process monitoring, process control, equipment monitoring, environmental monitoring, energy management, asset management, predictive maintenance and advanced diagnostics.

What makes this range of applications possible is the advanced diversity techniques designed to achieve reliability greater than 99%. When best practices like three or more communications paths per device are applied, the reliability is significantly higher—approaching 100%.

The WirelessHART standard employs five methods of diversity: time, coding, frequency, path and power. Here's my brief summary of each from the white paper.

Time diversity involves the use of intelligent data transmission scheduling to minimize collisions and recover from losses. WirelessHART uses synchronized time division multiplexing.

Coding diversity uses the radio spectrum where specific transmissions can be separated from noise and other simultaneous communications.

Wireless devices use frequency diversity (a.k.a. channel hopping) to dynamically choose different communications frequencies to avoid jamming or to mitigate interference from other wireless systems.

Path diversity comes from the self-organizing, mesh-communications network formation of wireless devices in a point-to-multipoint fashion back to the automation system and/or asset management system.

The final diversity technique used in the WirelessHART standard is power diversity where radio power transmission is controlled to a minimum level to destination devices to cut down on radio frequency noise for other devices using the same frequency spectrum.

I hope some of this background helps give you an appreciation for the techniques used to achieve high wireless communications reliability. The proof comes by giving it a try in your plant on measurements not currently possible or practical to wire.

Tags: WirelessHART | communications diversity | cable replacement | HART communications | time diversity | coding diversity | frequency diversity | path diversity | power diversity |

June 12, 2008 in Interoperability, in Measurement, in Technologies, in Wireless | Comments (0)

Courtesy of Emerson's VP of wireless technology, Bob Karschnia, I received a draft copy of a whitepaper circulating about redundancy in WirelessHART device networks. It's not yet finished so I don't have a link, but here are some of the key thoughts I gleaned from it.

Redundancy, in this context, is defined as a duplication of critical system components to reduce the probability of a failure caused by a single component. This redundancy is available at three levels including the network of wireless field devices, the access points and the gateways to the control and/or asset management systems.

Starting with the wireless field devices, the WirelessHART standard supports communications redundancy through multiple paths (spatial diversity), multiple transmission frequencies (frequency diversity) and multiple timing possibilities (time diversity).

Consider a wireless temperature transmitter mounted in your process communicating with other wireless devices—say a pressure and level transmitter. This device creates a self-organized communications path through one of the other devices back to an access point or directly to a wireless gateway. If the path through this device is obstructed, the temperature transmitter will retry at a slightly different time, frequency and path to the other device. If it fails, it will retry—again adjusting time, frequency, and path.

As we discussed in an earlier post, Planning Your Wireless Instrument Installation, it's important that each wireless device have at least two other devices to communicate with to provide alternative paths when needed.

An access point is a specialized WirelessHART device with a high-bandwidth communication interface to the gateway. Multiple access points can be connected to the gateway to provide path diversity and increased bandwidth across the network. There is no limit to the number of access points in the field network.

At the highest level of the field network is the gateway, network manager software and security manager software. The network manager performs scheduling and routing services. The security manager performs security key generation and storage as well as field device authentication services. All three components can reside within a physical gateway or can be distributed in separate gateways.

Using a mechanism similar to redundant controller pairs available in most automation systems, primary/backup redundancy management is being developed and stress-tested for these gateways.

I'll keep a sharp eye out for the finished whitepaper and update this post with a link.

Tags: WirelessHART | sensor network | field network | wireless transmitters | wireless device network | communications redundancy |

May 1, 2008 in Interoperability, in Technologies, in Wireless | Comments (0)

There's a great article on The Institution of Engineering and Technology's website, Industry Unplugged, by Emerson's Mike Ferris. Mike is with the Smart Wireless team in the Rosemount Measurement business of Emerson Process Management.

Mike's conclusion describes why process manufacturers might consider wireless field networks (a.k.a. wireless sensor networks.) He writes:

Wireless offers the ability to add additional measurement points to previously unreachable or unaffordable places throughout the process plant. This means greater access to information about the process and also the health of devices. Wireless mesh networking solves the problem of reliability within tough non wireless-friendly areas. Security issues have been addressed and in WirelessHART the process industry has an open standard to work with. By adding plant wide wireless networks it is now possible to improve the availability of this extra data to those that need it most.

Mike notes the adoption of wireless networks in our homes and offices and how it has become a part of our daily lives. This has not been the case in process manufacturing plant applications. A number of reasons he cites include a limited range of sensors and transmitters for acquiring data, security concerns, power concerns, and a lack of industry standards. Most wireless solutions were point-to-point, which prevented the ability to scale if the application required it.

These concerns led to the WirelessHART standard that I discussed in an earlier post. The architecture scales, installs in a straightforward way, and has well thought through security. For more on the underlying IEEE standards and protocols, this data sheet provides a good summary.

The main objective of WirelessHART is to be fully complementary to the wired HART standard. As such, it extends standard functionality like electronic device description language (EDDL) and provides process manufacturers a similar user experience whether the HART device connects wirelessly or via wires.

In the article, Mike offers application examples as opportunities where process manufacturers might give wireless field networks a try. I'll summarize his ideas in a bulleted list:

• Applications not justifiable when wiring installation costs included
• Remote devices in hard-to-reach areas
• Uninstrumented operational blind spots
• Existing HART devices with no way to deliver diagnostic information
• Manual readings done in hazardous locations
• Automating operator rounds
• Incremental measurement points
• Measurements on rotating or moving plant equipment (ex. lime kilns, rail cars, portable skids, etc.)
• Safety relief valve emissions monitoring
• Safety shower flow

Of course, many of these examples are possible. It's more the case that they are not practical once you factor in the wiring installation. It's kind of like your home. Some things are more trouble than their worth to do when wiring is involved. With a wireless option, things get a whole lot simpler and more doable.

Tags: WirelessHART | wireless field network | wireless sensor network | operator rounds | safety relief valve | safety shower |

April 23, 2008 in Wireless | Comments (4)

I read Dick Caro's, Which Way Wireless article published last Friday on the ControlGlobal.com site. It discusses WirelessHART and ISA100.11a and their paths to standards. He describes ISA100:

ISA100.11a is the name of the first standard being developed by the ISA SP-100 standards committee. The committee was officially chartered in 2005, with an editing team created in early 2007 to actually write the standard. Completion of the standard's first draft is scheduled for November 2008, and it may be that this schedule will be met.

Let's check this schedule against past standards to get a reading of when products might be expected.

The only standards effort in which I was fortunate to participate was the original launch of the OPC standard—then called "OLE for Process Control." A task force with Microsoft in a consulting role and five automation suppliers: Emerson (then Fisher-Rosemount), Intellution, Rockwell Software, Opto 22, and Intuitive Technologies announced the initiative at the ISA show in October 1995. The objective was to create a real-time communications standard based on Microsoft's OLE and COM technologies. Emerson served as master editor for this initiative.

The first draft of the specification was released in December 1995 and a second draft in March 1996. Three global seminars were held to teach interested parties about the standard's scope from April through August of 1996. Version 1.0 of the specification was release at the end of August 1996.

A beta release of the initial DeltaV system came out late in the fall of 1996, and the general release occurred in the spring of 1997. It was one of the first, if not the first, OPC server and OPC client commercially available. From the announcement of the task force in the fall of 1995 to commercially available products in the spring of 1997, this has to be one of quickest standards development efforts in process automation history. This standard, now referred to as OPC-DA, is maintained by the OPC Foundation and is still widely used today as a way to integrate software, systems, and devices.

I think this effort progressed quickly because Microsoft technologies were becoming increasingly important in process automation solutions and the existing method of communication, DDE, had its limitations that most acknowledged.

I haven't been real close to the WirelessHART path to standard, so I called Terry Krouth, Emerson Process Management's Chief Technology Officer, to understand its path to a standard. The wireless portion came with the HART 7 specifications formally approved by the HART Communication Foundation (HCF) members last June and authorized for release by the HCF board in September.

The HCF launched the WirelessHART initiative in November 2004. Its objective was to establish a wireless communication standard for process applications and enable wireless access to existing HART devices whose installation numbers more than 20 million. More than 25 companies were involved in its development including most of the major automation system suppliers. This HCF whitepaper, Why WirelessHART, shows a timeline with the major milestones on its successful path to ratification.

Terry noted that while the WirelessHART spec was being written, an extensive field-testing program was designed and conducted. Hundreds of prototypes were installed in actual field conditions to verify that the specification correct and workable. To make sure the standard would meet its objective, use cases of application scenarios were developed to make sure the standard could be used. HCF also donated these use cases to the ISA100.11a effort in June 2006.

Just last month, Emerson announced it is taking orders for the first products compliant to the WirelessHART standard. This comes a year and a half after the first wireless field network products became available in October 2006. Like the OPC standard, it takes time once the final standard is ratified until products become orderable and commercially available from the automation suppliers.

Like the immediate value OPC standard created around interoperability, the WirelessHART standard is making around "hard to get at" diagnostic information. I've chronicled some of the successful applications like wellhead pressure measurement and tank farms level measurement.

Other applications that have been spotlighted include railcar temperature measurement, temperature profiling, hot strip mill water flow, and remote pumping.

WirelessHART-based field networks open up possibilities to provide diagnostic information that is not practical or perhaps even possible to get at with conventional wiring. Process manufacturers are quickly realizing the value when they install these networks as these examples demonstrate.

Update: I'd also like to point out a webcast, The Range of Wireless, that Automation World magazine is hosting. It will be held April 17, at 2pm Eastern U.S. time.

Included in the panel will be Ron Helson, Director of HART Communications Foundation. I'll do another update when/if this webcast is archived.

Tags: WirelessHART | field network | SP100 | ISA100.11a | OPC | OPC-DA | HART Communications | device diagnostics |

April 14, 2008 in Interoperability, in Wireless | Comments (0)

I received an email from Anand Iyer. He's a certified project management professional (PMP) and a project manager in Emerson's engineering center in Pune, India. His project experience covers the gamut from pharmaceuticals, bulk drugs and intermediates to oil, gas and petrochemicals.

He's sent me a paper he's written entitled, Collaborative Measurement Control System Engineering. It describes how measurements close to one another in the process can collaborate with one another to verify their operation. He describes an example around a distillation column:

Now let us take two temperatures (bottom temperatures) in a distillation column and a level measurement. When the level is normal, the two temperatures are same or have a fixed relationship between them. TI1 is placed at a lower level in the column (near bottom) and TC2 is at a higher level (and used for Temp. control). Now TC2 is generally used for control. We can safely say that if Level is normal, and TC2 is under maintenance, TI1 can be used for control (with a minor adjustment to Setpoint if required). Thus Level and Thermocouple TI1 put together can "collaborate" the measurement of Temperature-measurement TC2.

Anand contrasts the traditional approach to a failure with how collaborative measurement strategies can be used in control strategies to avoid outages or process disturbances. In the traditional approach:

…the first thing done if an element were to fail was to swap the elements (either during the shutdown caused by the failure) or by a planned outage or having the loop in manual and doing the swap. At times, we have also used our ingenuity and just swapped the wires at the analog inputs and tuned control setpoints to have the plant up and running in a very short time. And hopefully, in all that chaos, someone had the presence of mind to record the swap on the wiring diagrams.

Using a collaborative measurement strategy:

…says that if level is not low and TC2 is not available then TI1 can be a valid measurement. We alarm the operator that TC2 is not available, fine tune the setpoint if required… All this occurs automatically and there is no outage or disturbance that could result in quality issues.

He extends the thought to Foundation fieldbus devices where the final control elements themselves can perform the logical evaluations and select the available primary or collaborated measurement, increasing the overall robustness of the control strategy. Anand also extends his thinking to wireless devices and how they could be used in a collaborative measurement environment—not as a primary measurement, but as a collaborative measurement to check on other devices nearby.

I hope you'll give Anand's paper a read and add your thoughts.

Tags: collaborative measurement | project management professional | PMP | Foundation fieldbus | distillation column | measurement strategy | control strategy |

March 12, 2008 in Control Strategies, in Distillation Column, in Foundation Fieldbus, in Measurement, in Project Services, in Wireless | Comments (0)

Recently my Emerson RSS news Feed alerted me to a wireless application on a North Sea oil and gas platform. I sent a note to the team involved with this project asking about their perspectives.

I received great notes back from Jeremy Fearn, a Smart Wireless Specialist based in the United Kingdom and Rolf Jenssen, a manager in our Norwegian Asset Optimization organization.

The overall challenge this oil and gas producer faced was the desire to measure annular pressure of the wells remotely by replacing the local pressure gauges. These measurements monitor the integrity of the tubing and annulus in the area between the production tubing and well casing.

Now, from my days on oil and gas platforms in the Gulf of Mexico, I recall that adding pressure measurement around the wellheads can be difficult and cost prohibitive. As Jeremy points out, this requires cable tray, cables, installation, drawings, man-hours, transportation and accommodation of the team to do all this. Also, the areas around the wellheads are classified as hazardous areas.

The team found the easiest and least disruptive way to replace the existing local pressure gauges was to use a gauge adapter with the Rosemount wireless pressure transmitters. This provided a direct replacement of the manual gauges with the wireless devices.

Another challenge was the distance between the wireless gateway and the room with the automation systems and AMS Device Manager software. Jeremy described their solution to use the fiber optic option for an Ethernet connection to the gateway. A short length of fiber optic cable was used to connect from the wireless gateway to a nearby cabinet room. This room contained spare optical fibers, which allowed the team to connect through to the process Ethernet backbone.

The platform already had AMS Device Manager software used for on-line diagnostics of 125 valves equipped with HART DVC controllers. AMS Device Manager also included an AMS OPC server. This software pulled in all the wireless pressure readings from the wireless gateway. From here, the data was passed to an OPC client on the host automation system. The AMS software also tagged all the parameters in the wireless HART transmitters, making it easy to select a parameter showing the overall quality of the measurement. This meant the quality of the measurement also could be transferred to the operators on the automation system. For detailed information about the status, configuration and health of the wireless transmitters, AMS Device Manager with EDDL files is used, clearly showing any failures.

Rolf also noted that the automation system's OPC client during the set up uploaded all of the values and parameters available from the AMS OPC Server, taken from all the platform HART devices including the wireless devices. After the selection of the pressure, temperature and the overall quality value, the team deleted the whole upload, but the selected values for the OPC links were now updated continuously to the operators, included the annular pressure measurements.

Initially, the staff engineers thought that two wireless gateways would be required, due to the density of the platform and production equipment. It turned out that only one gateway was required. All devices were able to communicate with the gateway. In fact, the device mounted furthest from the gateway still found a direct path! As more devices are added in the future, the strength the self-organizing network will be increased from additional wireless signal pathways.

The team took two days less than expected to complete the installation, and the oil and gas producer's staff has performed similar installations on other platforms without help from Jeremy or the other wireless consultants.

The real benefit is that the annular pressured is monitored continuously by the operations staff rather than twice a day through manual readings. Pressure drop in the annulus might indicate a problem with the well. These continuous measurements provide operators an opportunity to take corrective action much earlier to help avoid well rework and lost production.

Tags: wellhead | annulus pressure | annulur pressure | EDDL | OPC server | self organizing network |

March 11, 2008 in Asset Optimization, in Measurement, in Oil & Gas, in Wireless | Comments (0)

Dr. José A. Gutierrez is Corporate Director of Technology at Emerson. As such, he not only advises our wireless experts in Emerson Process Management, but also across the other Emerson businesses.

At the recent ISA Expo, he presented the paper, Reliable Wireless: Mitigating the coexistence Challenge. His key point is that through a number of communications diversity techniques, high communications reliability on the order of 99.9% or higher is achieved. These diversity techniques are supported the IEEE communications standards and are used in the new wireless field network standard, WirelessHART.

José had quite a bit of expertise to share and has a long history of participating with many standards bodies. Some of these include IEEE LAN/MAN, editor-in-chief of the IEEE 802.15 Working Group-Task Group 4, program manager of the ZigBee Alliance, board of directors' member of the Wireless Industrial Network Alliance, and chairman of the Networking Working Group of the ISA SP100 committee.

He began his presentation by defining the term coexistence from the IEEE 802.15.2-2003 Part 15.2 standard:

The ability of one system to perform a task in a given shared environment where other systems have an ability to perform their tasks and may or may not be using the same set of rules.

Collisions and coexistence issues can happen when two or more packets overlap in both time and frequency with sufficient energy to interfere with one another. Coexistence can be measured by the end-to-end message delivery success rate overall all operational conditions.

Different country's governmental regulations address the sharing of the radio frequency (RF) spectrum in different ways. The common approach has been in assigning different bands for applications such as TV, AM and FM radios, cell phones, toys to name but a few. You can get an idea of how these frequencies are divided with the U.S. frequency band allocation chart. A personal aside—it also makes for a great eye chart!

José discussed the unlicensed bands referred as ISM bands, short for industrial, scientific and medical bands. These bands are allowed for usage in a variety of applications and in some cases with worldwide availability. Only device certification is required for use in this band. Limits are imposed on the radiated power of devices transmitting at these frequency and they require governmental certification for the country in which they operate. These bands include 900MHz (902-928 MHz), 2.4GHz (2.4-2.4835GHz), and 5.7 GHz (5.725-5.875Ghz). For you non-electrical engineers, an Hz or Hertz is one frequency cycle per second. These unlicensed bands are very crowded.

The good news for process manufacturers is that the responsibility rests with automation suppliers to get their wireless devices certified for use.

The presentation covered the various ways information could be transmitted on these frequencies. It's enough for a future post, but I'll list some of the methods here: narrow band, frequency hopping, direct sequence spread spectrum (DSSS), orthogonal frequency division multiplexing (OFDM) and ultra wide band (UWB).

Tying all this back to coexistence, the IEEE 802 standard committee is the authority on wireless coexistence and ensures that these technologies will effectively coexist with all previous technologies.

José posed the question about what wireless suppliers can do to eliminate the coexistence challenge. The solution is to apply techniques that create diversity to mitigate this coexistence challenge. These diversity techniques include:

• Path Diversity: Mesh Networking
• Frequency Diversity: Channel Hopping
• Time Diversity: Time Division Multiplexing
• Power Diversity: Power control over multiple communication links
• Space Diversity: spatial location of sensing devices (not practical for WSNs)
• Coding Diversity: Use of advanced DSSS technology

The key for wireless field networks is to use a combination of these techniques to deliver the necessary high end-to-end message delivery success rate for reliable wireless operation. These diversity solutions used in IEEE-based standards applied in industrial applications including DSSS, OFDM, and UWB and used in the WirelessHART standard help eliminate coexistence issues as one of your considerations.

You can learn more about wireless basics, the technologies, cases for how they can be applied in plant applications and IT considerations by visiting the on-line wireless courses at PlantWeb University.

Tags: WirelessHART | wireless coexistence | wireless field network | ISM band | narrow band | frequency hopping | direct sequence spread spectrum | DSSS | orthogonal frequency division multiplexing | OFDM | ultra wide band | UWB |

October 31, 2007 in Interoperability, in Technologies, in Wireless | Comments (3)

You may have seen quite a bit of news coverage (here, here) on wireless technology as it applies to plant instrumentation. At the recent Emerson Exchange, Emerson also announced some wireless news.

If you are an automation engineer, you might have thought about some applications where you would like to try this technology.

Your best course is to start with a simple business case. Perhaps the operators perform rounds to get readings from gauges and instruments not connected to the automation system. Having this information and associated diagnostics coming from wireless devices could possibly make your plant's instrument technicians more efficient.

I caught up with Mark Sagstetter in Emerson's Rosemount Measurement business. He recently went to a refinery along with John Biscone, a service technician in Emerson's Instrument & Valve Services business. Operator and instrument technician efficiency was the very business case this refinery was pursuing. Mark and John were contracted to provide their expertise to help plan the network and installation process of the wireless instruments and gateways. Much like the early days of digital bus technologies, this expertise can help automation engineers establish best practices for planning and executing future wireless installations.

In the course of a two-day site visit, they worked with the plant engineers and identified five process units including four tank farm locations that met the criteria for increasing operator and instrument technician efficiency.

My understanding when talking with Mark is that there are basically two overall best practices to follow when implementing a wireless field network. The first is planning the wireless network and the second one is the network installation.

When executing the best practice of planning the Self-Organizing wireless networks, Mark and John like to have scaled site drawings. Unfortunately, in this case, scaled drawings were not readily available. Necessity being the mother of invention prompted the team's great idea to use Google Earth to generate site maps. They used the printouts during the walk-through of these process units to help envision device locations, gateway locations, plot anticipated communications, and to help identify possible impenetrable situations.

As part of the best practice of planning the network, it is a good idea to plot at least two paths of anticipated good communications for each instrument. Using a color-coding scheme, with one color to mark anticipated good communications paths and another color to mark potentially interrupted paths of communication, John and Mark were able to use this process to help understand how the network may function when installed. It also helped to understand, plan for, and possibly eliminate possible pinch points and/or possible impenetrable situations before the actual installation.

With every Self-Organizing wireless instrument being capable of being a router (sending and receiving messages from other instruments), possible pinch points and impenetrables are easily overcome. This is accomplished with the addition of measured points or instruments that act as routers or range extenders.

During the installation-planning portion of the site visit, Mark and John recommended the plant engineers follow the wireless installation best practices. To do this, the plant engineers would need to power and commission the gateway first. Then install, power, and commission the instruments, starting with the instrument closest to the gateway and continue working outward from the gateway. The instruments' connectivity to the gateway should be verified each time after installing, powering and commissioning the instrument.

One thing I noted in my conversation with Mark is that the instruments mount with standard process connections. Engineers have been using these standard connections for years. The actual mounting location for the instruments and gateways were determined by providing a forearm's length (a measurement device every instrument technician has with them at all times) of space between the antennas and any wall or metal structures to avoid signal attenuation.

Installation would continue by powering, installing, and commissioning instruments outward from the gateway, until all the devices have been brought on-line. By installing the instruments in this fashion, the actual formation and connectivity of the wireless Self-Organizing network can be compared with what was expected during the best practice of planning the network.

Beyond the immediate need to help the plant engineers plan a smooth installation at this refinery, Mark and John helped them establish best practices to aid in future wireless projects/installations.

Tags: wireless field network | self organizing | wireless site planning | site drawings | wireless best practices |

October 25, 2007 in Measurement, in Project Services, in Wireless | Comments (2)

The ARC Advisory Group's Wil Chin has an industry trends report published today on Emerson's Asset Optimization group. The report, Emerson Asset Optimization Division Enhances Solutions, looks at the technologies and expertise this plant asset management (PAM) space. I've added hyperlinks in some of the quotes where more information is available.

In the area of plant connectivity with business systems the reports states:

…the Asset Optimization Division continues to add AMS Device Manager connection options to simplify the implementation of PAM solutions, such as wireless device connectivity, Profibus/HART interfaces, and motor starters and drives solutions.

Wireless smart field devices, a growing area of interest, is described:

…wireless field devices based on the soon to be released WirelessHART standard, which is now supported by virtually all automation systems and field device suppliers. ARC believes wireless field devices provide a low-cost conduit for accessing stranded diagnostic information to enable PAM solutions, and it is a low risk first step for manufacturers to experience wireless technology.

The wealth of diagnostics from smart field devices can take some thought on how to incorporate because:

…users struggled with updating hard-to-change maintenance practices despite their best intentions. Because the plant workforce is multitasking to the max, few available resources could be applied to the implementation and management of new technologies and best practices. PlantWeb Services were introduced to help clients get the most out of PAM investments.

Asset prioritization was one of the services cited:

…users want to know which of the asset health alerts are critical, ranked in importance to the performance goals of the enterprise. Asset Prioritization provides a systematic methodology combined with the domain experience of Emerson's professionals to quickly prioritize assets into a Maintenance Priority Index (MPI). The index is determined in a six step process that considers business criteria, asset criticality, operational criticality, probability factors and others to determine the MPI.

Machinery health was a final area described in the report:

…Machinery Health Management solutions consisting of high-end portable machinery health analyzers, machinery health transmitters, machinery health monitors and machinery performance monitors, which all integrate with the AMS Suite predictive diagnostics application, including to Emerson's Ovation and DeltaV control systems.

The combination of technologies to monitor the production process assets combined with experts who can work with process manufacturers to incorporate this diagnostic information into work practices provides a way to improve performance.

Tags: asset optimization | plant asset management | PAM | HART communications | Profibus |

August 28, 2007 in Asset Optimization, in Wireless | Comments (0)

Control magazine provided excellent blog coverage of the recent ISA Wireless Summit. Control's editor in chief Walt Boyes in his post, Editorial Comment! offered his review of Emerson's John Berra's speech:

I just want to add that I am floored with the honesty and accuracy of what John Berra said this morning. He is exactly right. I want everybody to read what he said, and I'm going to ask him for the text of his remarks, so I can post them as an open letter on ControlGlobal.com. I hope he agrees.

John did agree and the speech text is available on the ControlGlobal.com site. Walt has blogged frequently on the efforts and difficulties in creating standards in the process automation industry. I'll highlight some of John's points from the speech.

John began with the benefits and noted that technology for technology's sake is not enough:

But if what we do as a technology doesn't transfer into allowing plants to run better, safer…it isn't going to survive.

Lack of information can lead to situations like unplanned shutdowns:

When you dig down into what causes unplanned shutdown, you find that it is usually the result of something quite simple, that we didn't know about. Most of the incidents that occur in plants can be traceable to things like that.

He discussed how wireless allows affordable access to information and offered the example of how wireless video cameras have provided affordable security solutions. In the process industries, manufacturers have installed 20 million HART devices, but "almost nobody has invested in the wiring needed to monitor these devices together." A wireless adaptor for these devices can free the stranded diagnostics and send them back to the control system to help see more of the plant and avoid situations like unplanned shutdowns.

With regard to the path to standards, John notes how competing standards like those that we see in the consumer space with Blu-Ray and HDVD slow market acceptance and the suppliers' recovery of R&D costs. John said:

Standards increase user willingness to buy. They give us confidence the approach we're taking will be accepted in the marketplace. But mostly, standards are good for our customers. That's why Emerson has supported standards efforts for a long time. We continue to contribute people, time, money and intellectual property. Our engineers are active in both SP-100 and WirelessHART activities. We have introduced pre-standard wireless products so users can start getting experience and benefits right away – but guaranteed that buyers will have a path to eventual standards. People ought to get started.

The development of standards has historically been a challenge in the process automation industry. John notes some of the experiences with the fieldbus standards development as an example. End user involvement is critical in the process to focus the efforts around the benefits and to develop the use cases for how the technologies will be applied. John recommended:

1. Move as quickly as possible to provide practical standards at the field level.
2. Take advantage of wireless standards already in place at levels above the field sensor network, and fill in the gaps.

On the first point, John notes that the HART Communications Foundation and ISA SP-100 committee have more in common than not. They agree upon the IEEE 802.15.4 radio and mesh network technology.

He urged the SP-100 team to take advantage of the work already done by WirelessHART and focus their efforts on the remaining portions of the standard.

John also noted that that the SP-100 team has role in addressing issues outside the IT-based wireless standards space in hardening, ease of use, and plant network management.

He summed everything up:

There's no question that arriving at a standard can be a struggle. But it's not about one faction or another winning or losing. It's about coming to agreement on how to make it easier for users to put this wonderful technology to work. And if we don't succeed, we all lose. The sooner standards are in place, the better for everyone. We need to get on with it. Suppliers will sell more products, and users will get more of the results that make wireless so valuable. The wireless potential of unlocking predictive intelligence so people can have a fighting chance to make their plants run better– this is what an automation professional is standing ready to deliver, and wireless is a key to delivering those benefits.

Update: Welcome readers of Gary Mintchell's Feed Forward blog! Gary points to Automation World magazine's Wes Iverson, who has a great summary article, High Interest, Slow Adoption for Industrial Wireless which includes his take on John's speech.

Update 2: Eric Murphy,at the OPC Exchange Blog, looks at John's speech and compares it with the efforts on furthering the OPC standard. Have a read of his post, Wireless and the Familiar OPC Story and add your thoughts.

Tags: wireless | ISA | SP-100 | WirelessHART | mesh network | 802.15.4 |

August 1, 2007 in Interoperability, in Wireless | Comments (0)

I came across an email that the ISA Honors & Awards Committee has selected the paper, Improving PID Control with Unreliable Communications, for its excellence in documentation award. Emerson's Deji Chen, Mark Nixon, Terry Blevins, Willy Wojsznis and the University of Texas, Department of Computer Sciences' Jianping Song and Aloysius K. Mok wrote the paper.

The paper examines PID control in a wireless network where intermittent loss of communications is likely to happen. It identifies the poor dynamic response of standard PID algorithms in this loss of communications scenario. The team proposed an enhanced PID algorithm to improve dynamic response under these conditions.

Terry Blevins summarized the paper well in an earlier post on the Modeling and Control blog. The post, PID Modifications for Unreliable Communications describes the situation:

One of the technical challenges is that the 2.4 GHz spectrum defined by IEEE 802.15.4 is also used by Wi-Fi and Bluetooth devices. Also, some electrical devices found in industry generate noise in this frequency band. Thus, at times it is expected that a transmission will be corrupted. To help minimize the impact of these other devices on communications, the Time Synchronized Mesh Protocol (TSMP) selected for wireless HART uses frequency hopping. Even so, at times it is expected that multiple transmissions of a measurement used in control or multiple communications of control actions to an actuator may be lost.

Terry describes how the loss of communications can cause the PID loop to continue executing and wind up due to the reset action. This reset action can be disruptive to the control of the loop. And, if the derivative (the D in PID) action is used, the loss and resumption of the control measurement signal can cause a spike, again bumping the control of the loop.

The Emerson and UT technologists worked through a solution to minimize the impact of this loss of communications. Terry sums up the change:

However, by modifying the reset and derivative calculation to account for the time since the last measurement update, then it is possible to minimize the impact of loosing multiple measurement transmissions.

If you want to look at the math behind this innovation, check out the overview presentation, PID for Unreliable Communications, given at ISA 2006.

Congratulations to the team for their contribution to furthering the advancement of wireless technologies in process automation!

Tags: wireless | PID | reset action | derivative action | IEEE 802.15.4 |

July 17, 2007 in Control Strategies, in Interoperability, in Wireless | Comments (0)

Walt Boyes, Editor in Chief for CONTROL magazine, has been closely reporting wireless technology and associated standards efforts in his Sound Off!!! blog. Some recent posts include:

Wireless-- who's to blame?
What about Wireless HART?
Are SP100 and HART Wireless Back on Track? Inquiring Minds Want to Know!
More Emerson Wireless
Bob Karshnia, from Emerson, speaks out on wireless
Emerson Declares Wireless...is it war?

Bill Morrison, Emerson Process Management Group's Director of Worldwide Marketing Communication responded to several of these which Walt posted in today's Emerson Speaks Out on Wireless! post.

A key point which Bill makes is:

Like several of our peers in the HART Working Group, we enthusiastically pursue the development of a standard. We openly share learnings gained from our trials with the Working Group. In fact, nearly 5 months ago (December, 2005), Emerson posted an open letter to the HART Foundation pledging our commitment to the donation of IP in an effort to further the standard. Our commitment to collaborate on a standard is clear, demonstrated through action.

I happened to be in the very first meeting where the OPC communications standard initiative was kicked off in the mid '90s. Our technology organization took the lead as master editor of version 1.0 of the specification. Obviously the commitment in time, energy and expense for participation on these standards bodies would not happen without Emerson's commitment to seeing these open, interoperable standards become reality.

Tags: wireless | Foundation fieldbus | HART | OPC | open interoperable | standards |

April 25, 2006 in Interoperability, in Wireless | Comments (0) | Trackback (1)