The growing sophistication of complex electromechanical systems, such as vehicles, aircraft, and industrial equipment, means that validation test must become more rigorous to keep pace with innovation. To ensure the safety, reliability, and quality of these systems, acquiring accurate data during testing is fundamental.
To meet these needs, test engineers are moving away from centralised measurement systems that can be susceptible to noise, and toward distributed measurement nodes, in which the digitisation and signal conditioning occurs as close to the sensors as possible. “However, more distributed measurement topologies create new challenges. DAQ devices must not only withstand harsh test environments but also acquire synchronised data over an entire system and scale and integrate seamlessly. The new National Instruments FieldDAQ devices from Test Dynamics are the most rugged NI DAQ devices ever created,” says Stephen Plumb, sales manager at Test Dynamics.
He explains that it is important to ensure that your distributed application can handle an unexpected failure of a device or connection. “When implementing a distributed system, the measurement devices typically are located within the same test environment as the device that is being measured—as close to the sensors as possible. This often means that the measurement device can be exposed to harsh and demanding conditions where standard desktop equipment might give inaccurate data or fail entirely. Ensuring that your signal conditioning and DAQ equipment can survive the test environment helps guarantee that you get accurate data the first time and eliminate the need for costly retests.”
Possible requirements for a system could include extreme temperature ranges for product validation testing, shock and vibration survivability (if the system is to be mounted directly to a machine), or hazardous location certifications to ensure the system can safely operate in marine or explosive environments.
Plumb points out that, although it is possible to design enclosures for any DAQ system to meet various ruggedness requirements, it is often more cost effective to purchase a system already tested and certified to survive the conditions. Design, materials, test, and compliance costs can quickly add up, in addition to the time to properly go through these steps, in developing and integrating one’s own ruggedness solutions. Vendors such as Test Dynamics can amortise these costs over thousands of units and offer the same benefits at a lower price.
FieldDAQ devices have an ingress protection rating up to IP67 (dust- and water-resistant), can operate in -40 °C to +85 °C environments, and can sustain 100 g shock and 10 grms vibration. In addition to field readiness, these devices were designed to be thermally stable, delivering minimal accuracy drift over a wide temperature range. For example, the FieldDAQ thermocouple device maintains 1.19 °C absolute accuracy throughout the full -40 °C to +85 °C operating temperature range.
FieldDAQ devices also include premium signal conditioning and diagnostic features to reduce the effect of external interference and increase measurement accuracy. Built-in anti-alias filters prevent high-frequency noise from being aliased into the user’s signal and channel-to-channel isolation eliminates noise from ground loops in the user’s system.
Even with rugged DAQ hardware, exposing a system to harsh, real-world conditions increases the risk of costly downtime. This risk is amplified for tests that must run 24/7 for days, weeks, months, or even years. Reinforcing the reliability of a system is crucial to minimise problems from unforeseen events such as untimely software updates or network failure.
FieldDAQ helps keep your test running with data link redundancy and real-time OS support. In case of a broken or damaged network connection, ring topologies mitigate the risk of data loss by automatically redirecting data through an alternative route. You can easily achieve a ring topology with FieldDAQ, using the built-in integrated switch to daisy chain multiple units together.
FieldDAQ lowers the risk of software interruptions due to multitasking with NI Linux Real-Time OS support. This minimises the components required, which reduces the probability of system failures. Users can connect FieldDAQ to a variety of Linux real-time hosts including industrial controllers, CompactDAQ, and CompactRIO.
“As technology advances and physical systems become smarter, not only has the amount of data required to understand these systems increased, but so has the need to accurately correlate the different measurements being acquired. The bottom line is that FieldDAQ allows one to distribute the DAQ devices around your application, closer to the measurement. Our team of National Instruments specialists is able to device a FieldDAQ solution suited to the user’s exacting needs,” says Plumb.