Data Recorder

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The term data recorder (also often called a data logger) is frequently used to describe a self contained, stand alone DAQ system or device. These products contain a number of analog and digital inputs that are monitored, and the results or conditions of these inputs is then stored on some type of local memory (e.g. SD Card, Compact Flash card, Hard Drive).

Data recorders are often deployed when a full PC-based DAQ system is not possible or desired. Often this can be because the installation is in a hostile environment that most PCs cannot tolerate or because a PC-based data acquisition system would simply be too large. Unfortunately, security is also frequently a consideration and though the more powerful devices may be valued at many thousands of dollars, they are not as prone to theft as there is not too large a market of a "hot" data recorder.

Though there are no firm rules, a data recorder is typically considered to offer higher speeds and performance than its data logger cousins. They can be deployed while connected to a host PC but are more typically deployed as stand alone devices. Once the application is programmed into the unit, it is placed in location, the various input (and output) signals are connected and the logging application is started. Sensors commonly connected include: Thermocouples, RTDs, Thermistors, strain gages, load cells, pressure sensors, event counters such as turnstiles, liquid level and many more. (Some smaller units are designed to simply monitor temperature and RH, and require no external connections at all).

Examples of where these devices are used abound. A few of these examples are shown below:

• monitoring acoustics or vibration in either a room or on a structure, commonly using an ICP (a.k.a. IEPE) vibration sensor
• Monitoring temperature, pressure, strain and other physical phenomena in automotive and in-vehicle tests including monitoring traffic and data transmitted on the vehicles CAN bus.
• Monitoring stress and strain in large mechanical structures such as bridges, steel framed buildings, towers, launch pads etc.
• Environmental monitoring for quality control in food processing, food storage, pharmaceutical manufacturing, and even monitoring the environment during various stages of contract assembly or semiconductor fabrication
• Monitoring environmental parameters in temperature and environmental chambers and test facilities.

These are only a few of the various applications which count on data recorders to log and store data. Almost any time something needs to be measured and the data available for future reference, one of these flexible units may fit the bill.

Software for most data recorders is provided as a simple "canned" configuration application that allows the user to select the inputs to be logged, the signal conditioning or linearization required, the sample rate, alarm conditions etc. Also the software needs to define how the logging application is to be started (e.g. time of day or based on a button push) and how it will be ended (e.g. in four hours, at a certain date/time or on an alarm condition). The software may also allow the user to select alarm conditions which may be used to control one or more outputs that can be used to notify of the alarm or even perform an emergency shut down of the system. Finally the application software typically is used to help the user download the data from the recorder into an application that is used to analyze the logged data (e.g. Excel, MATLAB).

Many systems offer a fixed configuration where the number and type of inputs (and outputs if applicable) cannot be changed. More powerful recorders such as UEI’s UEILogger series allow the user to match the I/O data recorder’s I/O to match the actual application’s requirements.

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