Tag Archive for: NI

Engineering Data Acquisition Tools: cDAQ-9189

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When our engineers go on the road to troubleshoot structural component failures or machine vibration problems, they grab their laptop with iTestSystem installed and Pelican case containing an NI CompactDAQ (cDAQ) chassis and an assortment of C-Series modules, accelerometers, and strain gauges. The cDAQ chassis that they typically use is a cDAQ-9189 ethernet chassis, which is ideal for data logging.

The cDAQ-9189 is an extended temperature TSN enabled 8-Slot Ethernet chassis designed for distributed sensor measurement systems. The chassis controls the timing, synchronization, and data transfer between C Series I/O modules and your laptop. Since the chassis has an integrated network switch and is TSN enabled, measurements from multiple chassis are synchronized by simply daisy-chaining chassis with an ethernet cable.

For more information about the cDAQ-9189, DAQ hardware rentals or iTestSystem, contact Josh Fishback at (844) 837-8797 x705 to assist with your data collection needs.

How Do I Collect Vibration Data with iTestSystem and a cDAQ?

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Our test engineers collect vibration data on rotating machinery using four basic tools.  We use a Laptop computer with iTestSystem software to stream accelerometer and rotational/speed pulse sensor data from a National Instruments cDAQ equipped with vibration and voltage input modules.  The video above shows how to collect vibration data using iTestSystem and a cDAQ.

Vibration Test Equipment

Vibration measurements are usually derived by analyzing data collected from IEPE accelerometers mounted to the rotating machinery structures and components of interest with magnetic bases or epoxy and a rotational/speed pulse sensor.  Typical rotational/speed pulse sensors are magnetic pickups excited by gear teeth and keyways or optical sensors triggered by reflective tape adhered to the rotating machinery.

The most important part of the data collection process is choosing a sample rate.  If  you choose a sample rate that is too low, the data you have collected is useless.  According to the Nyquist Theorem data must be sampled at a rate that is at least 2X the highest frequency you wish to record.  2X the highest frequency is a minimum number.  Most test engineers like to sample from 2.5x to 10x higher than the highest frequency they wish to collect.

Typical general vibration measurements are sampled at 2kHz.  However, vibration data collected from accelerometers and gear teeth pulses which is used for phase and speed measurements, and bearing fault detection, and torsional vibration determination must be collected at much higher sample rates like 50kHz.

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For more information about collecting vibration data, iTestSystem, data logging or test equipment rental, contact Ryan Welker @ (844) 837-8797 x702.