The first wireless transmitters were put to use in the early 20th century, using radiotelegraphy, or Morse code, as their mode of communication. Later, as modulation made it possible to transmit voices and music via a wireless transmission, the medium came to be called radio. So although not as spectacular as the cell phones, iPods and other consumer gadgets that we correlate with wireless communication today, this technology has been functional and serviceable for quite a while. Similarly, although the industrial applications for wireless capabilities might lack the sex appeal, developments in this marketplace have had a tremendous impact on enhancing product capabilities.
 Monitoring capabilities, like what is depicted here with Banner’s SureCross Wireless Networking units, can offer solutions for both liquid and dry material via analog sensors and wireless, battery-operated nodes. |
Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or all of the communication path. Some monitoring devices, such as intrusional arms, employ acoustic waves at frequencies above the range of human hearing. These are also sometimes classified as wireless. Looking more closely at the industrial realm, wireless capabilities are primarily utilized for:
- Process control monitoring, such as fluid levels, flow rates, temperature or operating speeds. Being able to remotely monitor these items simplifies safety and production, as manual inspections can be replaced by examining several parameters from a computer screen that doesn’t even need to be on-site.
- Reducing the amount of wire that needs to be run throughout a product or in connecting a group of sensors. This saves money and can produce quicker communications between varying points of contact.
The Need For Speed The most significant, and also most obvious benefit of implementing wireless functionality into industrial products is the elimination of cables. They not only limit mobility, but also the potential to realize a piece of equipment’s true capabilities. With remote monitoring being such a building block of preventative maintenance and efficiency-focused plant operational strategies, monitoring and communication limitations, due to the reliance on cables, can place manufacturers at a significant disadvantage.
“All of our systems are used in between areas that can be measured no other way,” offers Jason Blume, an electronic systems project manager with Sensor Products. An added benefit here is the ability to access information from machinery located in all parts of a facility. This is key, as plant engineers can save a great deal of floor space by not having to accommodate monitoring responsibilities. So equipment can be positioned with greater consideration given to workflow, ergonomics and spatial efficiency.
 Products like this web-based, wireless temperature monitoring unit from Measurement Computing can aid preventative maintenance functions and improve operational efficiencies in industrial applications. |
Banner Engineering points to three major benefits of wireless implementation - portability, mobility and scalability. Sources at the company feel that the ability to more easily move and expand a wireless system or products, as the application requirements and environment change and grow, is the biggest benefit of utilizing products that are integrated with wireless technology. Others point to the convenience of wireless-embedded products in the industrial setting as being dependent upon the number of access points that are made available, which, in turn, will help improve the quality of the transmission. “The greatest functionality in Crystek’s offerings are a combination of higher and higher frequencies with lower and lower phase noise,” states Ramon Cerda, the director of engineering at Crystek Corporation. “The higher the bit rates being sent, the greater the demand for high frequency oscillators with very clean output signals (low jitter, low phase noise).”
In consumer wireless equipment quartz crystals are used, primarily due to their lower cost. In industrial applications oscillators are more widely specified because the performance parameters are more critical. Industrial wireless platforms operate slower than consumer products because the communication between machines, sensors or monitoring stations has to be more precise.
With a cell phone, if the signal is interrupted, the call is dropped, and other than the inconvenience associated with that communication disruption, no critical data is lost and the cell phone or PDA in question can still function. In the industrial realm, these interruptions can be disastrous. That’s why these products utilize deterministic wireless.
Deterministic means that there is a guaranteed response time to ensure the message is received in the specified or allotted amount of time. That’s why to ensure these signals are generated and received accordingly, industrial networks and equipment will utilize frequency hopping capabilities.
If the response time on a machine or sensor network is compromised, the unit or units in questions will usually shut down, similar to a dropped call on a cell phone. The problem is that instead of just re-dialing, operators have to stop the production workflow and get operations back on track.
Because industrial applications require a level of reliability that consumers do not, Banner built a deterministic RF network that can predictably default outputs to specified conditions in the event of a lost link. This translates to the elimination of unknown results, which can happen when a cable is cut. Rather, the company states that their network users can define exactly what will happen to an output if the communication link is compromised via either a default, last value, alarm, etc.
Additional challenges in applying wireless technologies to industrial products can include IC power constraints, bandwidth limitations, multipath fading and signal interference, as this operating environment has plenty of other equipment generating background noise and interference that these signals must combat. This, of course, is in addition to the need for more durable products that can withstand the industrial environment, and the constant pressure on manufacturers to pursue lower cost alternatives at every turn.
Another issue is unit power, especially at the sensor level. “We do not use wireless in consumer applications,” states Blume. “The main reason is battery life. Most consumers are not prepared for the complexity of our systems, and therefore have trouble understanding that wireless also means battery power.”
Wireless products that require DC power still, obviously, require wires. Therefore, to be truly wireless solutions these products should be able to use or include a power source at each remote node location. This means that if a corded power source, such as a battery box, is used, it must provide power to support the radio communication and the input sensor/s.
In responding to this operational dynamic, Banner’s team points to the growing use of flexible power options that can use whatever power is present, or can power themselves via a remote power supply. This approach can also mean tapping into sources like solar power cells in maintaining a wireless application.
The Road Ahead
“Challenges specific to Crystek in designing for wireless technologies are primarily size and power consumption,” states Cerda. “Many chips sets are now being designed to work at 1.8 volts and lower with ever decreasing form factors. This puts the pressure on us to maintain the pace on the R&D side in order to keep up.”
Blume agrees on the battery power front, but adds concerns relating to the integrity of a streaming signal. “Real time systems require a constant streaming line of data,” he states. “By the nature of wireless, signals are not constant and can cause the data to be thrown out of order or lose contact.”
Preventative maintenance has emerged as a leading application for wireless products in the industrial setting, which lends well to recent developments in sensors and transmitters for tracking operating or environmental temperatures, motor speeds or torque/stress factors on other critical internal components.
Level analysis for both liquid and dry material has been another area where Banner has seen their wireless products successfully implemented. The biggest benefit here is offering more accurate analog sensors that don’t need a lot of power to function appropriately. In this situation, the sensor uses a portable battery that can last for years.
Looking forward, Cerda sees some developments from the consumer side aiding industrial wireless applications. “In the very near future, HDTV will be the only format broadcast in the U.S.,” he states. “This is big-scale wireless technology being implemented all across North America. Crystek has developed specific ultra-low phase noise oscillators for HDTV broadcast equipment that provides low jitter and low-phase noise sources as an absolute requirement.”
As these developments become more prevalent throughout society, they will be tweaked to better handle the rigors of industrial use. In the above example, the use of an oscillator instead of a crystal is encouraging for those seeking a potentially higher-quality signal that can be proven and refined in consumer applications before being placed in critical industrial equipment settings.
As this technology progresses, much of it will probably originate on the consumer product side. But as it becomes more refined, wireless capabilities will play a huge role in helping designers provide more efficiently-operating products and equipment. Whether that application be with RFID inventory and logistics controls, machine-to-machine communication, control data monitoring or preventative maintenance programs, the ability to process information more efficiently will play a significant role in the success of industrial operations around the world. This will prove especially true as we continue to compete in an economy that recognizes fewer and fewer borders.