Non-contact sensor standard ensures reliability and availability

Louise Smyth

Carsten Koska explains how a non-contact sensor standard ensures reliability and availability

In 2008, Knick Elektronische Messgeräte and Endress+Hauser decided to join forces and promote a common superior standard for digital process sensors. Relevant patents were cross-licensed between the partners. Knick contributed its inductive sensor connector system InduCon and its expertise in digital data storage in the sensor head. Endress+Hauser opened its existing Memosens system for further development. The companies adopted the name Memosens for the unified standard. Since then, the shared technology has become widely acknowledged as a leading standard for non-contact data transfer and voltage supply between electrochemical sensors and industrial transmitters.

Advantages over analogue sensors

Analogue data transmission is very susceptible to disruption due to factors such as EMC interferences, contaminated or corroded sensor cable contacts, insufficient grounding or faulty equipotential bonding of measuring components. None of these have an impact on the inductive, digital Memosens technology: the sensor and cable coupling are galvanically isolated, enabling non-contact transmission of supply voltage and data. A chip in the sensor head digitises and stores the measured values as well as the configuration and calibration information. This data can be used for sensor diagnostics and predictive maintenance, which includes monitoring sensor operating time, wear, remaining service life and maximum temperatures.

If the stress matrix shows that a sensor’s performance suffers because of extreme pH values or temperatures, the sensor’s adaptive calibration timer can be adjusted and the prescribed calibration intervals shortened. “Employing a predictive approach means not to wait for a sensor to fail, risking an incident on a weekend or during a night shift. Instead, sensors under a big strain are now identified and regularly swapped out for pre-calibrated sensors,” says Dr Dirk Steinmüller at Knick. “In the past, if there was any problem with a sensor, a PAT engineer had to calibrate the replacement sensor on site. Digital Memosens sensors, however, can be reliably pre-calibrated in the lab. The actual replacement process is then very simple and does not require highly qualified staff.” Pre-calibrated Memosens sensors achieve up to 40% longer lifespans compared to conventional, analogue sensors.

Portal boosts know-how

Knick has set up an online learning platform at Using many short clips and interactive graphics, the basics of the digital sensor technology are presented in a way that is easy to appreciate and understand. There is a particular focus on actual application scenarios: users will
learn Memosens solutions for demanding measuring tasks that would push the limits of conventional sensors.


Continuous development

Throughout the past 10 years, the technology’s inventors have remained committed to enhancing it. A wide, ever-growing range of pH/ORP, conductivity and oxygen sensors provides solutions for all kinds of applications and industries. In addition, Knick
offers a comprehensive portfolio of two- and four-wire process analysers with different bus interfaces, automated cleaning and calibration systems, retractable fittings, compact transmitters and portable analysers. All Memosens components are fully interoperable.

Knick has announced several product innovations to be showcased at this year’s Achema trade fair in Frankfurt, Germany. The manufacturer is expanding its range of compact transmitters for the Memosens standard by adding MemoTrans, an extremely slim two-wire multiparameter solution that supports 4-20mA and HART communication and can be used with all Memosens sensors for measuring pH/ORP, oxygen, or conductivity. By fitting the transmitter and sensor interface into a single space-saving unit, MemoTrans enables a direct, loop-powered connection of the measuring point to the process control system. Thereby, Memosens technology can now also be employed in applications requiring no displays or control units installed on location, as well as in applications without sufficient space for a conventional transmitter. An integrated Bluetooth interface provides technical personnel with flexible and convenient access to the measuring point directly on the spot. It allows them to configure the compact transmitter and the sensor with the MemoTrans app, which is available for iOS and Android smartphones or tablets. The app also displays all current sensor and diagnostic data. In addition, the new compact transmitter supports the HART fieldbus standard and can therefore be accessed from the control system or via a HART handheld.

Other Memosens innovations announced for 2018 include new sensor types and the MemoGate gateway module for connecting four Memosens sensors with different Ethernet interfaces. Trade fair visitors are furthermore invited to check out a new generation of Stratos analysers featuring two channels and multiparameter capability, and a multicolour, plain-text display that simplifies operation and configuration.

Carsten Koska is with Knick

Recent Issues