1 February 2006
Water System Unplugs
Ethernet boosts efficiency at growing Canadian burgh and halts expensive quick fixes
By Victor K.L. Wong and Thomas Dunn
The City of Coquitlam sits in the heart of the lower mainland on the west coast of British Columbia, Canada, about 20 minutes from the U.S. border. Its population has more than doubled in the past 20 years. Growing from a handful of homes in the 1970s to more than 9,400 homes and numerous commercial services, the city has become responsible for 500 kilometers of water mains, 400 kilometers of sanitary mains, and 450 kilometers of drainage.
Fast-growing municipalities like Coquitlam face challenges not only to replace tired technologies, but to implement appropriate security measures with those technologies. Monitoring facilities through supervisory control and data acquisition (SCADA) and adding remote video surveillance and data logging for security at remote sites are at the forefront of such challenges.
With any municipal or industrial growth comes a need to move data from remote locations to a central monitoring facility. That's where Ethernet network environments come in. They use radio instead of cable to provide network connectivity for field radio telemetry unit (RTU) locations. Communications vendors now demonstrate Ethernet networks from 115 KBps up to 1 MBp using spread spectrum radios and 900, 2400, and 5800 MHz radio bands. So industry can cost-effectively manage remote systems with enhanced bandwidth.
New wireless Ethernet network systems are scalable and flexible to ensure organizational network growth, which could work well for a growing city. The solutions also provide easy-to-deploy and easy-to-manage networks that allow remote management and control of network devices to reduce overall management and servicing costs. For SCADA systems, radio products for the 900 MHz band and data rates from 115 to 512 KBps are the most cost-effective.
SCADA on the move
Most municipalities today already have SCADA systems in place, but those using radio communications as the primary backbone face limits through small bandwidths, with only minimal bandwidth for retrieving data logs and applying remote surveillance. With the growing popularity of SCADA systems in larger municipalities for monitoring remote water and sewer facilities, even small towns now use basic remote telemetry devices to monitor alarms and provide call-out to operation personnel.
North American governments and municipalities operating distribution systems use telemetry systems for fresh water, waste water, and storm water. Managed traffic-light control, security, irrigation, lane control, and vehicle location systems use a combination of computer monitoring at central facilities and remote field devices, including RTU and programmable logic controller (PLC) products.
Since 1991, the City of Coquitlam had operated its water and sewer distribution systems using RTUs and radios to provide basic control and monitoring with connections to an 800 MHz trunking system, operating at data rates of 600 bps. The central monitoring facility was running a DOS-based HMI software package, but it wasn't enough. The trunking radios introduced long delays in granting permission to transmit during peak periods.
After years of growing and investing in short-term fixes to minimize delays in trunking radios, re-evaluate telemetry system requirements, and upgrade to intelligent RTUs and a Microsoft Windows-based HMI software package, the City of Coquitlam stopped all expansions with its existing RTU product to determine which RTU option met design criteria needed for future expansion. The RTU products could do data logging, so they were great for flow monitoring stations, increasing data throughput of the spread spectrum product line. But after more trial and error involving recommendations for a license-free spread spectrum for new stations and further investigation and radio tests, the final decision rested with adding Ethernet capability to their product lines.
With Ethernet, the city could supply high-bandwidth data transmission using addressable packets of information to route data between locations, which connect via network cable. Thirty years earlier, this technology didn't easily support long-distance cable runs needed for field RTU use. Fiber-optic cables can move data over longer distances, but the costs are still too high for the amount of data a SCADA system would typically transmit.
Minimizing security issues
Because all wireless data networks offer the opportunity for data interception and insertion, it's impossible to guarantee absolute security in a wireless or even a wired network. But you can minimize those risks by providing layers of security to the wireless Ethernet network. Today's terrorism concerns have led manufacturers to enhance security for door-and-hatch entry alarming by adding video surveillance to better respond to potential threats to reservoirs and pumping stations. Field personnel need to use more and faster information carrying notebook computers and handheld devices. We can't address these problems without more bandwidth in SCADA system communications design.
Using wireless Ethernet in municipal applications, such as those at the City of Coquitlam, could open up new possibilities for integrating data, voice, and video into one single network. Applications might include a combination of traditional SCADA and telemetry services, remote video and surveillance monitoring, and emergency voice services while leveraging existing infrastructures. These applications are possible because of the larger bandwidths a wireless Ethernet system could provide over conventional radio systems.
Some municipal agencies have even reassessed their security readiness and are now installing new or upgraded security and surveillance systems, including wireless video, to help enhance the security system. This is a first step in mitigating damage to a water supply system. Ethernet systems could also piggyback voice data over the radio network using voice-over-Internet protocol. This provides a cost-effective alternative to a traditional telephone network in municipal systems where traditional services are not available or where you might need a temporary voice connection, such as at water reservoirs or watersheds.
Investment pays off
The City of Coquitlam wasn't going to be left behind. Before getting proposals for the new wireless Ethernet data network, the city was already on the wireless bandwagon, having started its video surveillance program using other wireless radio products.
Already, the city is enjoying improved data response time for alarms and analog information. In fact, the city realized the possibility of using video data on this network within the bandwidth limits and will evaluate for remote access to e-mail once they move more water and sewer sites from the old system to the new Ethernet data system. They also anticipate a need for more store and forward repeater sites when they start the expansion. The city will integrate access point radios with new fiber-optic cables, installing them in the next two to five years as part of a hybrid system.
About the Authors
Victor K.L. Wong (firstname.lastname@example.org) is chief engineer, SCADA Systems, at Dayton & Knight Ltd. in North Vancouver, BC, Canada. Thomas Dunn (email@example.com ) is chief technologist, SCADA Systems, at Dayton & Knight Ltd.
Wired or Wireless? You Make the Call.
By Ellen Fussell Policastro
The design to unplug is not a simple question when it comes to Ethernet technology, and it depends who you ask and what your application is. Industry experts say there are pros and cons to wireless and hardwired Ethernet technology. "Hardwired has been around longer, and more people are comfortable with it," said Eddie Lee, Moxa Technologies national product sales manager. There are fewer variables for problems with wired, he said, "but on the flip side, wireless is one of those technologies where there are so many variables that offer newer more efficient solutions."
Wireless is great for saving costs in installation and in its flexibility, said Tim Black, Wonderware's device integration manager. "This will become more prevalent as the technology evolves," he said. Black also believes the increase in wireless use will give manufacturers more flexibility and lower their installation costs, at least after they get comfortable with its reliability. "Just like cell phone technology today, wireless computing and networking will become a standard for many types of applications," he said.
People have been comfortable with wireless for years, but some are still overcoming imperfect technologies from the past, Lee said. "Some people, like the old school plant floors guys, say wireless Ethernet is not reliable for industrial applications," he said. "Yet those same players are now jumping on the bandwagon."
Not so fast. Wired Ethernet is safer, more reliable, faster, and better overall, said Kraft electrical leader Evan Hand. People only use wireless "when costs (long runs or frequent changes) or application requirements (portability) overcome wired advantages," he said. Yet he does admit "there is gradual acceptance for specific applications. I do see it becoming a tool that engineers can use to solve control problems," he said, especially where they need portability or frequent changes.
Black said the advantage of wired Ethernet, at least at the moment, is its higher speed capabilities with a better range. "The faster the rate with wireless, the shorter the distance you must go," he said. "Therefore, I would say in most manufacturing environments, where speed and reliability are key and where disruptions of data flow are intolerable, wired is more prevalent. In SCADA environments that might require flexibility and range, and where speed is not so important, wireless is perfect. There will always be a mix of wired and wireless implementations," he said.
While Hand sees a place for wireless, he still believes most installations will remain wired in the future. "I do see wireless as providing a solution for specific application problems," Hand said. "This includes use in the real-time control network, especially where portability is an advantage." But he said he doesn't think it'll replace all wired connections, "at least not until technology or bandwidth is expanded to allow a lot more traffic on a wireless network," he said. "I think one of the potential roadblocks in large scale acceptance might be tools to implement and secure the wireless network."
Both sides want secure space
What about security? If a food manufacturer is concerned about protecting recipes, "that's different than a general municipality that someone could hack into and turn things on and off," Lee said. "Bringing down a wireless Ethernet network or system at a facility or petrochemical plant by hacking into the network would require a lot more effort than cutting wires." It's more likely events are the result of "disgruntled ex-employees rather than from some outsider trying to hack into the network," he said. "Hardwired systems with passwords are just as susceptible, if not more than, a wireless network," he said. "But you still can't overlook the fact that it's much easier to set off a bomb than take the time to hack into a wirelessly encrypted network."
Hand disagrees. "You have to have physical access to tap into a wired environment. You can attack from a distance with wireless," he said. Plus, wireless has the disadvantage of "susceptibility to denial of service type of attacks without being logged into the network (you could jam the radio frequencies)."
"Even with secured wireless connections, it is easy to gain access to the network," Black said.
Don't overlook cost savings
Lee believes there are advantages to hardwired. "You don't have the additional due diligence of selecting the most appropriate wireless technology," he said. And using hardwired cuts out the confusion. "You have fewer options with hardwired, which only come into play with the actual components you use to transmit Ethernet data, such as hubs vs. switches vs. routers. They're all components of hardwired systems, but you're no longer debating what kind of hardwire. You're just talking about maximizing traffic efficiency and speed within hardwired systems. There are fewer opportunities for hardwired problems and fewer variables for causing network problems."
But if you have the correct technology that would make it reliable for that application, wireless can save a ton of money and labor time for the application, Lee said. "With something as simple as connecting a data network from one facility to an expanding manufacturing facility across the street, to do it hardwired, you'd need a permit to dig under the road, and you'd have to pull conduit. With wireless, it's as simple as setting up a transmitter and receiver and making sure they're within the correct distance," he said. "There's a huge benefit and efficiency of time and money, assuming you have a reliable wireless solution."
Spread Spectrum Defined
Spread spectrum technology is a method of taking data that might normally travel as one message on a single frequency, and breaking it up into small packets (a series of bits containing data, control, and source and destination addresses information). These packets then travel over many frequencies in the band. Actress Hedy Lamarr helped develop spread spectrum techniques during World War II to prevent unauthorized interception of messages. While the military has used spread spectrum in their bands for the past 60 years, it's only been available commercially over the last 10 years. The most prevalent method of using multiple frequencies is by hopping from one frequency to another every fraction of a second until the message fully transmits.
The early 1990s brought a new radio frequency band (between 902 MHz and 928 MHz) called spread spectrum radio communications. Data rates in this band typically operated around 19.2 Kbps, although we still used 9.6 Kbps. RTU equipment operated through serial communications RS-232 data ports with a maximum speed of 57 Kbps, and the limiting factors still resided with the data radio maximum throughputs. Users of spread spectrum radio technology no longer had to license a frequency or pair of frequencies from Industry Canada or the FCC. The often lengthy frequency coordination and assignment period from Industry Canada was no longer a barrier with the use of license-free spread spectrum products. Clients who once had significant delays in data communications on the licensed channels due to data traffic levels and number of remotes could now add more remote stations without sacrificing system performance.
Find more information on wireless and Ethernet at www.isa.org.
The Ethernet Mesh by Kevin Burak and Roland Gendreau
An Overview of Wireless Networks by Matthew N. Anyanwu and Houssain Kettani
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