Understanding Wireless Technology for Process Industry Applications

Wireless has become a “hot topic” as more manufacturers in the process industry investigate the viability of deploying this technology into their respective facilities and distribution operations in order to minimize risk and/or optimize their asset utilization.

A number of automation end-users have recently begun implementing some wireless solutions in their facilities to solve ‘nuisance’ monitoring problems they currently have in their plants. Conversely, basic 868/900MHz radio technology specifically designed for integration into Remote Operations Controllers and SCADA systems, for example, has been widely used in Oil & Gas field automation for more than 15-20 years in some world areas.

It is interesting to note that even after some 20 years of service, the adoption rate for in-plant wireless solutions is still negligible at best. This phenomenon is most likely driven by the lack of industry accepted open standards, inadequate security, and insufficient scalability/flexibility of traditional wireless solutions. Also complicating matters are the differing preferences of frequency spectrum (868MHz, 900MHz, etc) in various world areas. Given the long-term implications of deploying new technologies, these issues don’t exactly give plant managers and engineers the confidence required to broadly deploy wireless technology into their facilities today.

However, the leaders in the process industry realize these are not indefinite issues. Therefore, many of these leaders are already beginning to develop advanced asset management strategies enabled by wireless innovation in order to meet their business objectives of increasing overall operational performance and/or enabling a more successful project execution.

Meanwhile, others in the process industry are faced with the added complication of having assets which are geographically dispersed, such as remote customer bulk inventory tanks, across a state or even the entire country. This is not a trivial problem since logistics managers are challenged every minute with the conflicting requirements of preventing customer tanks from running empty –which could lead to a process shutdown at a customer site- while at the same time trying to significantly reduce their distribution costs. Effective logistics planning is not an easy thing to do well; however, several leading industrial gas, chemical, and specialty chemical companies are driving towards wireless enabled web based inventory monitoring solutions which allow them to accomplish these critical business objectives. In these industries, customer service and cost containment are vital to creating and maintaining a significant competitive advantage.

With such wide ranging user needs, how can truly innovative and reliable wireless solutions be developed to solve so many of the high stakes operational problems encountered throughout the industry? First, one must acknowledge that there is no “magic bullet” (technology or solution) which can individually solve the myriad of in-plant and remote asset problems. That’s the “bad news”. The “good news” is that these end-user problems can be easily solved if one simply focuses on the root cause problem and match that need with the appropriate long–term viable solution which will help solve that particular problem.

With the prospect of being able to solve virtually any process or asset monitoring application, many people throughout the process industry view wireless technology as an exciting new innovation path for addressing issues which were deemed either cost prohibitive, not technically feasible, or lacking in ‘device-to-host’ dependability. This excitement in the asset management community is well justified with the expectation that knowing more about what is going on within the process, physical assets, and overall operations will lead to a safer and more profitable enterprise.

Exploring possible wireless technologies

Although there are numerous wireless technologies in existence today, only a few are specifically well positioned for the process industry. Why is that? Well, the process by which wireless signals propagate through the air, the amount of data carried (bandwidth), immunity to RFI/EMI interferences, susceptibility to physical obstructions, scalability, reliability, and obviously cost, vary across wireless network technologies. Therefore, many users are interested in making sense of which technologies may be applicable to them depending on the application. And more to the point, which technologies will drive solutions which are based on open standards since wide-spread deployment will have long-term implications in the plant or asset base. Readers may be evaluating some of these technologies for wireless asset management applications:

GSM/GPRS for web based monitoring applications

For monitoring applications of geographically dispersed assets which do not have a local host such as a DCS or RTU for data collection, web based monitoring solutions incorporating GSM/GPRS communications is typically the first technology considered.

Advanced web enabled monitoring solutions allow the combination of reliable intelligent field devices, dependable wireless capabilities with advanced power management, and a user friendly web user interface to formulate a complete remote asset monitoring solution.

For example, in a Vendor Managed Inventory application, a GSM/GPRS enabled multi-variable level measurement device will transmit monitoring data on a periodic basis (e.g. several times per hour, once per day, etc) via an existing telecommunications network to a central server where the information can be securely accessed with a standard internet browser. Flexible systems also allow the collected data to be linked to a user’s proprietary database.

Some integrated solutions with suitable data logging, advanced power and communications management, as well as measurement best practices are capabilities which can extend monitoring enhancements into other types of applications as well. Examples may include paper chart recorder replacements, analytical monitoring for reservoir water quality, or pipeline block valve position for auditing purposes.

In these applications, asset managers require dependable access to timely information in order to establish and maintain excellent situational awareness of their remote assets. This allows the logistics planners, for example, to prioritize their distribution routes in order to make deliveries only when they are needed and/or efficiently respond to quick ship requests from their customers. Another example could include giving gas distributors with regional pipeline distribution networks timely visibility into line pressure condition anomalies.

Introduction of Self Organizing Networks, 2.4GHz radios, and Wireless Ethernet

These technologies, if properly deployed, offer managers some new tools in optimizing their plant operations by breaking the cost barriers associated with collecting more asset performance information. Some applications could be as simple as adding cost effective measurement monitoring points to eliminate manual collection of field data, thereby improving the operator labor productivity. Or, in more sophisticated applications with a centralized asset management interface, wireless innovations will enable users to extract full diagnostics data and predictive intelligence from the devices which will then automatically notify the appropriate personnel of the precise problem before a process or asset problem can threaten a costly unit or plant shutdown. Understanding these technologies will provide insights into where they might be deployed to accomplish these objectives.

A wireless system has the following components: wireless node, gateway, and host. A node refers to a wireless device installed in the field. A gateway aggregates wireless devices into an access point which can then be integrated into a host system such as a DCS, Historian, or other interface – typically via a serial connection or anEthernet connection that supports protocols such as Modbus and OPC.

Self Organizing Networks

This is an emerging – yet very promising – wireless technology for the process industry because it may finally enable a wireless device platform from which open standards can be effectively developed. Since this wireless technology was originally envisioned for commercial applications with vastly different requirements, the development efforts needed to transition into industrial applications -while still exceeding user expectations- is proceeding rather quickly. However, it will take some time before a final standard is established.

The basic concept of Self Organizing Networks is that each individual wireless device also acts as a router for other nearby devices, thereby eliminating the need for costly site surveys. If one device cannot communicate back to the gateway because of distance or obstructions, then the message will be passed to another wireless device, and so on, until a reliable path to the host is established. This is a dynamically self managed network capability which can perform automatic corrective actions such as auto-recognizing authorized new devices into the network, re-routing communications when needed, and optimizing the overall network performance among other things. These networks, therefore, literally heal themselves if something goes wrong with one or more devices. Ease of use is also an important consideration factor, hence, all these sophisticated

tasks are handled without the need for any human intervention or required additional software!

The prospect of being able to easily specify and install such devices without worrying whether or not it will work due to line-of-site issues, sacrificing device performance, ignoring device intelligence, or propagating proprietary solutions with weak security is very enticing to many users. It also holds the advantage of being more energy efficient than traditional point-to-point wireless devices because of its ability to transmit at much lower radio power requirements.

Instead of having to “scream” from the device to the gateway, Self Organizing Network devices can “whisper” from device to device until it gets to where it needs to go. If a direct link to the gateway can not be established, then the communication across one or two ‘hops’ will typically solve the line of site problem -- although networks will be quite capable of efficiently managing many ‘hops’. Moreover, with advanced energy management capabilities and inherently lower power wireless protocols, devices will have a longer battery life or benefit from unique energy harvesting techniques.

Self Organizing Network technology will require a paradigm shift in thinking when it comes to how asset optimization can be cost effectively achieved, particularly since deploying more of these network devices will actually increase overall communication reliability as multiple pathways are created regardless of topology. This is counter-intuitive but nevertheless a highly valued unique attribute.

The three most common topologies are Star (point-to-point), Mesh (point-to-multipoint), and Cluster Trees which is a hybrid of Star and Mesh. These solutions typically operate in the 868MHz, 900MHz, or 2.4GHz frequency bands depending on the world area requirements.

It’s been Emerson’s experience that many different terms have been used to try and describe this innovation in wireless technology. These terms (Motes, Mesh, Zigbee, and IEEE 802.15.4) seem to be used interchangeably by many in the industry. Although generally accepted, there are some subtle but very important differences between those terms and Self Organizing Networks.

Motes strictly refer only to the actual wireless field devices/routers. Mesh is a reference to a specific topology made possible by this technology. Zigbee is the consortium which developed a standard used for commercial (building automation, etc) applications. The IEEE 802.15.4 standard specifically refers to the radio physical layer only. The term Self Organizing Network describes the full embodiment of capabilities, technology, and industrial application of this technology.

2.4 GHz Co-Existence

In many countries, the only license-free bandwidth exists between the frequencies of 2.405 GHz and 2.485 GHz commonly referred to as the 2.4 GHz band. Due to the limited license-free bandwidth made available by governmental regulating agencies, it is not uncommon to find several wireless applications occupying the same RF (radio frequency) bandwidth.

A typical process facility may have WiFi networks, wireless video surveillance, wireless personnel communications, and self-organizing networks all sharing the same 2.4 GHz bandwidth. This is made possible through several techniques that all allow various RF devices to share communication channels within the 2.4 GHz bandwidth as well as time available on each channel.

In particular, self-organizing networks are being designed as “good neighbors” so that they achieve greater than 99% reliability in communication, yet do not interfere with other RF devices such as WiFi networks. Techniques allow the self-organizing to only communicate when there is a clear channel as to prevent interruption as well as have the RF signal power so weak that it falls with in the noise level of the much higher power devices such as the wireless surveillance systems. A third factor is that the self-organizing messages are so short, that they are complete before other systems can be disrupted. Due to these techniques many self-organizing network can co-exist in the same RF bandwidth and same physical location with other RF devices so that scalability is practically endless.

High Powered 2.4GHz Radios and 802.11b/g Wireless Ethernet

Does one “compete” with the other? Are they used in conjunction with each other? Where and how are these technologies best used in the process industry? These are pretty typical straight forward questions but nevertheless important ones to ask. We should consider these two technologies for use at the gateway level of a network architecture since these are not practically implemented within devices today. Wireless Ethernet devices would be difficult to implement due to high power consumption and the market acceptance of 2.4GHz wireless transmitters is still well below 1% despite its long standing availability.

In the O&G field segment of the market, high power 2.4GHz radios have a long and successful track record which is not likely to change. What will change, however, is the type of data which will be added into the long distance (up to 20 miles is not unusual) communication links. As some of the gas field assets begin to mature, we should expect them to begin capturing more of the device intelligence in order to increase the overall productivity of the under to-moderately performing well sites. In some cases, this advanced capability is being deployed into new fields as well. The I/O count for these applications are typically pretty low, therefore, adding diagnostics data will not significantly challenge the bandwidth limitations of the frequency band.

Like many cities across the world implementing “wireless everywhere”, so too are many Asian enterprises including educational campuses, military installations, and – yes – industrial process plants. Any of the more innovative users are cost effectively deploying reliable wireless Ethernet access points throughout the plant in such a way that no matter where someone is located in the facility they can securely access the plant network. This makes for some interesting use-cases for wireless handhelds in the future.

This phenomenon is significant for a several reasons. One, wireless Ethernet provides sufficient bandwidth needed to concentrate advanced monitoring data into a relatively low number of cost effective access points throughout the plant. Second, contrary to some popular beliefs, 802.11, when implemented correctly, is actually a very secure and robust open standard. Third, it’s a well understood technology which is already in wide use within many manufacturing and business operations today. Lastly, it provides the most flexible and easiest paths for data integration into DCS, PC, Data Historian or other host.

Both of these technologies can (and already is) being deployed into plants today. However, due to data integration at the host, required bandwidth, reduction of RF (radio frequency) noise, and enabling increased functionality, wireless Ethernet would be the preferred platform for concentrating field device applications. Because of the extreme 10-20 mile distances and relatively low bandwidth requirements, 2.4GHz radios will likely continue as the preferred technology for integration into SCADA systems.

Closing comments

Wireless innovation is creating an exciting era in process and asset management by encouraging all in the industry to see things through a new lens. Some of these solutions are already being deployed in new ways for O&G, Municipal Water, In-Plant, Vendor Managed Inventory, and many other applications. Furthermore, Wireless HART and other open industry standards are beginning to emerge which will lead to solutions which solve many high stakes asset management problems which are otherwise cost prohibitive or technically challenging.

What about security? Security is by far the most frequently asked question regarding wireless technology for in-plant applications. For those concerned about the protection of wireless systems (some users aren’t), there are four components to an effective security strategy. State-of-the art techniques which are based, again, on open standards is the recommended best practice. It has been proven many times over that proprietary security systems are the easiest to crack. Encryption – this entails taking data and turning it into data packets which does not make sense to anything except a receiver which has the security key to decode the message. It is best practice to have this capability at the actual device. Authentication/Verification – this measure ensures that only valid devices trying to communicate on the network are permitted to do so. This prevents rogue devices or hackers from trying to gain entry through an access point. Anti-Interference – all this does is increase the likelihood that a message sent can be received some distance away even with moderate obstructions and/or RFI/EMI signal interferences. The most common methods accomplishing this are FHSS (Frequency Hopping Spread Spectrum) and DSSS (Direct Sequence Spread Spectrum). Simply put, signals are transmitted over various frequencies and if there is a block at one frequency, another will carry the message through. There is a common misconception that FHSS and DSSS, by itself, provide adequate security. For clarity, FHSS and DSSS is not the same thing as security. Key Management – poor key (codes) management can eventually defeat any of the above security measures if a disgruntled former employee, for example, maintains access to static keys and decides to cause harm. This would be akin to losing your bank card with your password written on the back. Obviously neither situation is desirable, so appropriate procedures and methodology should be implemented. Implementing all wireless security measures properly will result in a safe and secure network which can ultimately deliver highly value to the user. Therefore, users considering industrial wireless solutions should partner with automation leaders who are committed to providing all aspects of a secure and reliable network architecture.