Customers often data acquisition card different measurement purposes, DAQ different Labjack bridge sensor can achieve many measurements,
Are currently used as follows: Acquisition Card Link Chart LabJack:
connecting Sensor Type:
• a voltage or general 4-20mA signal acquisition
• acceleration and vibration measurements
• weight, pressure, strain measurement
• microphone and audio, audio measurements
• distance and depth measurements
• direct thermocouple collection
• direct heat or thermistor collection
Vibration sensors and acceleration:
a common IEPE or ICP accelerometer is type. It provides a high-level voltage signal decent, but the problem is that they need a special constant current excitation source, typically provide 2 mA to 10 mA at 18-30V. We do not offer such an excitation source, it will have to be together with the sensor sources.
As signals from these sensors, which typically can be directly measured, but sometimes you need AC - coupled out of DC offset that may require LJTick-InBuff module. Recommended when using ICP or IEPE sensor, also requires a corresponding signal conditioner. Looking for a signal conditioner, special excitation current source, and if necessary adjust the output signal of
gravity, pressure, strain sensor:
Wheatstone bridge is used to measure small differences in circuit resistance. This bridge circuit is commonly used for various types of sensors, such as load cells, pressure sensors and strain gauges. Sometimes these sensors are primitive, which may increase the signal conditioning to make them easier to use.
Load cells - most of the load cell is not the original signal conditioning of a bridge circuit. If the output is specified as an output similar to 2mv / V, then it is a primitive bridge. If the output is designated as high as 0-5 volts, + / - 10 V, or 4-20 mA, the load cell has signal conditioning, this application does not apply.
A pressure sensor - is the original number of the pressure sensor bridge circuit, and there are many signal conditioning. See pressure sensor applications described.
Strain gauge - is just a strain gauge resistive element, its resistance changes with strain. The change in resistance is small, so that the bridge circuit is generally used. If you plan to have only one or two strain gauge measurement, you have to add two or three resistance strain gauges or false (inactive), to form a full bridge (quarter and half-bridge).
Wheat compared with traditional analog output of the sensor, most microphones are faced with unique challenges. Typical microphone output voltage is low, the frequency is high, it is difficult to measure.
Miniature electret microphones columnar body inexpensive, simple to use a dielectric material to detect sound, but need amplified output signal. 1, requires a microphone connected to a bias voltage source, a resistor, a series capacitor is also required to eliminate the DC offset. The results of the small signals need amplified, and then input into the analog U3 / U6 / UE9 / T4 / T7. Grams of wind and sound, audio sensors
Distance and depth sensor
hydrostatic sensor suitable for measuring most within a few inches of liquid depth or some powders.
Good ultrasonic sensor be measured within a few feet, and can reach the target in unhindered to some extent. When selecting the ultrasonic sensor, it is important to consider the beam width and communication protocols, because the manufacturer offers a variety of protocols and beamwidth.
Other for measuring distance / displacement sensors include an infrared (e.g., Sharp), the pull wire, the LVDT, capacitive, inductive, eddy current type and laser type.
Thermocouple, RTD, thermistor sensor
if you measuring range of -50 to + 150 ° C, considered to use silicon temperature sensor. They are usually the least expensive solution, the simplest solution and the most accurate solution. Outside this range, the thermocouple is usually the best choice. Thermistors and RTDs look very accurate when you see the original size, but that the accuracy of temperature resistance. With sufficient accuracy difficult to measure the resistance, in order to achieve a predetermined accuracy of the sensor element itself. Digital sensors similar to analog silicon sensor range limitation is a great solution depends LabJack and software programs. T7 and T4 in a high level of hardware support for the SBUS sensor (EI-1050, SHT1x, SHT7x ), and therefore can be easily read any temperature and humidity in the software. Older devices (U12, U3, U6, UE9 ) provides advanced support through software, requiring a software application to call UD U12 or library. Other say SPI, I2C, asynchronous or single line of sensors are also an option, but requires a software application to make specific calls to LJM, UD U12 or library.
If you measure within the range of -50 to +150 ° C, considered to use silicon temperature sensor, instead of a thermocouple. See "temperature sensor" Apply described.
Understand the difference between resolution and accuracy.
T7-Pro是热电偶的最佳配置。U6系列具有与T7相同的模拟输入质量，但不具备在硬件上进行数学运算的能力(我们提供了一个UD驱动函数来处理软件中的数学运算)。T7-Pro和U6-Pro上的24位转换器提供了更高的分辨率(在较低的速度下)，但可能更重要的是，它提供了小热电偶信号，还提供了出色的噪声抑制。U3/T4与LJTick-InAmps是最便宜的方式获得体面的读数热电偶:
U3/T4: U3是唯一的usb设备，当与LJTick-InAmps结合使用时，为4个或更少的热电偶提供最低成本解决方案。T4是类似的，但有USB和以太网。参见U3/T4热电偶教程。
U6: U6(或U6- pro)是唯一的usb设备，比U3有更好的模拟输入。热电偶可以直接连接，具有比U3-LJTIA组合更好的性能。
T7: T7 (or T7- pro) having U6 (or U6- pro) the same analog input system, but provides USB and Ethernet connections (WiFi and the T7- pro). In addition, the device on the T7 EF system can be used to perform all the thermocouples math in hardware, so you can get a direct reading of temperature. See T7 thermocouple tutorial. U6-Pro / T7-Pro: and U6 / T7 is the same as the above information, but -Pro version sigma-delta 24-bit resolution and better noise rejection. In particular, at lower sampling rate, sigma-delta 50 will produce 60 Hz and rejection, which is a common problem thermocouple signal.
UE9 and U12: new applications should first consider U3, U6 or T7 series devices. UE9- pro thermocouple well in terms of performance, resolution and UE9 only about 1 degree Celsius, the thermocouple voltage U12 only distinguish within the original 10 degrees Celsius, and therefore usually requires an amplifier, such as EI-1040.
Silicon sensor type: in the range -50 to +150 degrees Celsius, silicon temperature sensor is generally more expensive than other types of temperature sensors, easier to use and more accurate. Since no additional components or only minimal, which provides a high level of linear voltage output, can be connected directly to the analog input of LabJack. EI-1034 is a silicon-based temperature probe, manufactured by Creative electronics by LabJack sales. It uses LM34CAZ sensor element from National Semiconductor Corporation. Providing LM34 10 mV / degF an easy to use. EI-1022 is a silicon-based temperature probe, manufactured by Creative electronics by LabJack sales. It uses LM335A sensor element from National Semiconductor Corporation. LM335A provides an easy to use 10mv / degK, but also requires a resistor.