Precision instrumentation depends on the accuracy, security, and reliability of its connectivity, yet connectors are often the weakest link. Find out what matters most when selecting connectivity solutions to enhance performance and usability in demanding test and measurement applications.

 By Fischer Connectors

Instrumentation designers and end users are constantly seeking better performance, greater reliability, faster data transfer speeds, and easier integration, use and maintenance. High-precision test and measurement applications call for innovative connectivity solutions that are both rugged and versatile. The best connectivity partners not only offer a wide choice of standard body sizes, styles, and contact configurations, they also work closely with designers to adapt existing connectors or develop customized solutions that fit the specific end-use application environment.

high-precision test and measurement instruments

High-precision test and measurement instruments that are used outdoors need to withstand aggressors like extreme temperatures, vibrations, abrasion, and wet or muddy conditions. Many are made of brass, stainless steel, or aluminum, and may be sealed to protect against dirt, water, and gasses. Rugged connectors also come in fiber optic, power, signal, and hybrid versions. Applications like remote sensors often use rugged connectors to protect the integrity of the data they collect. Key design criteria to be defined from the outset include the right level of sealing (environmental against liquids and dirt, e.g., IP68, or hermetic against gasses), shielding (EMI/RFI, 360°), number of mating cycles (e.g., 10,000); temperature rating (e.g., -50°C to +160°C). Other important factors to consider are size and weight, durability in harsh environments, and ease of use for safe and secure mating, maintenance, and cleaning.

Connectivity Solutions for High-Precision Test and Measurement Applications

The following three cases show how defining the right connectivity requirements, constraints, and opportunities upstream in the application design process helped overcome major roadblocks.

Case 1: ME-Meßsysteme’s K6D Sensors: Miniaturized Rugged Connectors for Accurate Data Transmission Even with Vibrations

Reliable measurement data is crucial for ensuring that systems and machines in robotics, medical technology, and the automotive industry operate safely and efficiently. Data showing which forces and torques are acting on axes are particularly important and need to be monitored constantly. One proven methodology for obtaining reliable results is strain gauge technology. The K6D sensors from ME-Meßsysteme GmbH rely on a combination of six independent strain gauge sensors. The forces in the three axes of the space, as well as the three moments around these axes, are precisely calculated based on the six sensor signals. The sensors have to transmit the analog and sensitive small signals from the process to the control computer at ever higher speeds. This is a major challenge, especially for small sensors with several integrated dimensions. The junction between the connector and sensor is the most critical in the entire system.

When testing connectors for use with its sensors, ME-Meßsysteme continually ran up against the same problems: the connectors were prone to vibration, too heavy, or complicated to assemble, and they were not waterproof. Machine vibration or movement at the solder joints caused connectors to lose the connection, resulting in errors in measurements and machine downtime to fix them. An optimal rugged connectivity solution was small enough to be easily integrated into the sensors, yet had the required 24 contacts, was resistant to liquids up to IP68, and ensured that data transmission remained fast and stable even with high accelerations and vibrations.

Fischer MiniMax Series connectors for test and measurement

ME-Meßsysteme’s six-axis force sensors use the powerful, robust MP11 connectors in the Fischer MiniMax Series. This solution met designers’ key requirements for low weight, very compact dimensions, high vibration resistance, and IP68 sealing.

Case 2: ITTH’s Scanning Systems: Secure Hybrid Fiber Optic Connectivity for Predictive Railway Maintenance

Brake systems used on trains are subjected to high loads, so you need to keep a constant eye on their condition. To enable brake shoes to be optically inspected during ongoing operations, Danish State Railways have installed scanning systems made by ITTH GmbH & Co. KG in the track bed. Each intercity train and each of its 40 to 60 brakes is uniquely identified using radio-frequency identification (RFID) tags. High-performance camera systems take photos of trains’ brake shoes as they pass through stations. Suitable connectivity technology is required to quickly and accurately transmit data from the measuring system to the computer system. Since the system is located in the track bed, the connectors also have to be robust and resistant to external influences.

While looking for the best solution for their system, ITTH came across robust, durable fiber optic connectors that overcame these challenges, thanks to hybrid technology that features two optical channels for data transmission and two electrical contacts. This enables high-speed data transfer. Their IP68 and IP67 sealing ensures that they withstand dust, rain, snow, oil, and gasoline on the track. The connectors’ easy mating and unmating allow quick assembly and disassembly. Moreover, the system can easily be lifted out of the track bed for regular maintenance without having to close the track.

Fischer FiberOptic Series connectors for test and measurement

ITTH’s scanning systems use the robust hybrid connectors in the Fischer FiberOptic Series. Combining two optical channels for data transmission with two electrical contacts, they transmit data accurately at a speed of 10 Gb/s. With IP68 and IP67 sealing, they resist external aggressors like dust, rain, snow, and even oil and gasoline.

Case 3: Piletest’s Pile Echo Tester: Reliable Cable Assembly for Ease of Use on Job Sites

Equipment used on construction sites has to be built to last. Piletest, a leader in rugged instrumentation applications, had developed its state-of-the-art Pile Echo Tester (PET) to test pile foundation integrity in harsh environments. However, the connector initially used in this instrument for pulse echo testing, or low-strain testing was not rugged enough and the company had many product losses due to technicians accidentally destroying the PET in rough outdoor conditions. Users often throw the PET in their trunk, or drop it in puddles or on concrete surfaces, and expect the PET to keep working on hundreds of pile tests per day. If a connector breaks, however, it cannot be fixed in the lab, since the PET is fully molded. The connector was thus the weak link.

To overcome this obstacle, the connectivity technology had to be rugged, ergonomically designed, and easy to use. Piletest worked with Fischer Connectors to design a cost-effective solution that met its stringent PET performance, reliability, and usability requirements. It chose a rugged seven-pin connector as the basis of a cable assembly project for its durability (10,000 mating cycles) and its 90° low profile, which ensured easy integration into the PET’s housing. Since the PET’s wireless option is used by many testers in the field, the connector also had to be compact, comfortable, and easy to handle and clean. The new solution enables testers to plug in and use the equipment with a simple click. Equipment damage is prevented, thanks to the connector’s 360° mating freedom and IP68-sealed, blind-mate, and non-magnetic quick-release locking mechanism. 

Fischer Freedom Series connectors for test and measurement

Piletest’s Pile Echo Tester (PET) integrates the multiple award-winning Fischer LP360 seven-pin connector from the Fischer Freedom Series. Its 90° low profile and ergonomics, as well as its plug-and-use technology and durability, perfectly matched the requirements for ease of use in harsh environments.


Accurate, secure, and reliable connectivity determines high performance in many test and measurement applications, yet connectors are often the weakest link. Identifying the pain points, defining application-specific connectivity requirements as early as possible in the design process, and seeking guidance from experienced connectivity partners can save considerable time, money, and effort. The result is improved performance, extended product life, and enhanced usability, benefitting both designers and users.

Like this article? Check out our other Connector Basics, test equipment, and high-reliability articles, our Sensors and Antennas and Wire and Cable Assemblies Market Pages, and our 2021 and 2020 Article Archives.

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