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JAN-FEB 2019

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INTECH JANUARY/FEBRUARY 2019 29 SYSTEM INTEGRATION Because EtherNet/IP uses the Com- mon Industrial Protocol (CIP), consistent device access is possible with one con- figuration tool. Devices become "objects" on the network that are easy to integrate. Once on the network, an object has a pro- file that allows sensor data to be assigned within the profile, without the need for detailed programming information. With digital sensors, digital transmit- ters, and control systems communicating, data can be easily and clearly communi - cated from the process to the host control system, and on up to the enterprise level. Data is no longer just the primary pro - cess variable, but also includes secondary process variables, sensor health, sensor performance characteristics, calibration information, and real-time diagnostics. All this information can be used to improve the process, optimize the performance of the instrument while extending its life, and maximize the productivity of mainte - nance personnel. With the advent of the Internet, these digital devices and systems are being further transformed and becoming part of the IoT. This transformation will take us to places and bring capabilities we never imagined. Let's look at the journey of one industrial process measurement over the past 50 years to see how it has been completely transformed by digital technology: pH measurement. Digital journey of one measurement The fundamental measurement of pH has been used across a range of industrial processes for many years. It is a measure- ment of the hydrogen ion activity in a sample and represents the acidic or basic nature of a fluid. The pH range is defined from 0 to 14. Determining a solution's pH began as a lab-based measurement. A sample was brought to a lab, and a benchtop pH system was used to measure the sample. The measuring system did not actually measure pH, but calculated pH based on a measured mV potential signal produced by the pH sensor. To do this, a bench- top pH sensor has two electrodes (a measurement electrode and a refer- ence electrode, enclosed in separate glass cells) and, due to the effects of temperature on the measurement, a temperature sensor is also required. Historically, with lab-based systems, the measuring electrode, reference elec- trode, and temperature sensor were three separate electrodes that were immersed in the sample while connected to elec- tronics that measured the low-level mV signal and converted this value to pH. This was truly an analog system and an off-line measurement that required a significant amount of operator effort, with a consid- erable time lag between when a sample was collected and results were reported. One of the first major changes in the measurement of pH was to integrate the three separate electrodes into one de- vice, which resulted in a "combination" electrode. The sensor was still an analog device with hardwired connections to the transmitter and had all the inherent problems associated with a hardwired, low-level analog signal. The next signifi- cant improvement in pH measurement was the introduction of digital technol- ogy to the sensor, enabled by continuing advancements in miniaturization (figure 5). And, as with all smart sensors, it allows new pH sensors to provide more data, and to operate more reliably. At the transmitter end of a pH instru- ment, the data communicated by a digi- tal smart sensor can be read and sent out to a control or asset management host system, also using digital communica- tions protocols. With the abundance of data residing in the sensor, and the abil- ity to digitally communicate this data to a digital transmitter and beyond, users now have the information to better operate the process and manage the asset. Although this example pertains to pH measurements, much of the discussion also applies to other process variables. Digital advancing Because of the technology advances in the past half a century, transmission from an instrument has evolved from just the primary process variable to a wealth of in- formation accessible up to the enterprise level. In the future, digital technology will continue to provide more information from instruments, with access from any- where in the world. A pH measurement is no longer just the pH value, it also includes the temperature, quality of the calibration, number of calibrations, overall operating time, operating time over critical process con- ditions, and much more. Tools are avail- able to turn this data into actionable in- formation, with virtually no limitations when it comes to improving operations and efficiency. n ABOUT THE AUTHOR Steven J. Smith (steve.smith@us.endress. com) is the senior product marketing manager – analytical for Endress+Hauser USA, responsible for technology applica- tion, business development, and product management of analytical products. He has a BS from the University of Wisconsin and an MBA from the University of Colo- rado. Smith has spent the past 30 years working in process instrumentation and control with Fortune 500 companies. View the online version at www.isa.org/intech/20190204. Figure 5. Smart sensors can store measuring and operating data, including serial number, calibration date, number of calibra- tions, offsets, pH applica- tion range, number of calibrations, and hours of operation under extreme conditions. RESOURCES "HART makes troubleshooting easy" www.isa.org/automation-basics-hart-makes- troubleshooting-easy "The Smart Evolution" www.isa.org/the-smart-evolution "Industry 4.0 for process" www.isa.org/intech/20170601

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