View source for DAQ1500 User Guide

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<metadesc>The Wheatstone Bridge Phidget measures up to 2 load cells or Wheatstone Bridge-based sensors and connects to a VINT port.</metadesc>
[[Category:UserGuide]]
==Part 1: Setup==
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== Part 2: Using Your Phidget ==

===About===
The DAQ1500 reads two load cells, strain gauges or Wheatstone Bridge-based sensors. The Phidget reports results as a voltage ratio. To convert from voltage ratio to a quantity like weight or force, see the Calibration Guide in the Advanced Topics section.

[[Image:DAQ1500_About.jpg|link=|center]]

===Explore Your Phidget Channels Using the Control Panel===

You can use your Control Panel to explore your Phidget's channels.

'''1.''' Open your Control Panel, and you will find the following channels:

[[Image:DAQ1500_Panel.jpg|link=|center]]

'''2.''' Double click on a channel to open an example program. Each channel belongs to the '''Voltage Ratio Input''' channel class:
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{{UGC-Entry|Voltage Ratio Input (Bridge Input):| Read data from a load cell
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In your Control Panel, double click on "Bridge Input":
[[Image:DAQ1500-VoltageRatio.jpg|center|link=]]}}

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== Part 4: Advanced Topics and Troubleshooting ==

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{{UGC-Entry|Choosing a Gain Value|
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The DAQ1500 has the option to change the bridge gain, which improves measurement resolution at the cost of reducing your effective range. We recommend starting at 128x gain and testing your load cell with the maximum load you expect to see in your system. If you get any saturation error events, you should lower the gain and test again. Here are the specifications that vary with gain:
[[Image:DAQ1500-gain.jpg|center|850px|link=]]
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{{UGC-Entry|Connecting Your Strain Gauge or Load Cell|
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Load cells are force sensors that can be used with the DAQ1500. To get useful data from load cells, they will need to be calibrated. Fortunately this is a simple process outlined in our guide on [[Calibrating Load Cells]]

For more information, see our [[Load Cell Guide]].
If no documentation is available for your strain gauge, it is possible to use a multimeter to determine how to connect it, provided there are no electronics in the sensor. Measure resistance between the 4 wires. There are 6 wire combinations - two of the wire combinations will have a resistance 20-40% higher than the other four. Select one of the two high-resistance combinations, and wire it into 5V and G on the DAQ1500. Connect the other two wires into +/-. Apply a load, if the V/V responds in the opposite way to your expectations, flip the +/- wires.}}
{{UGC-Entry|Measurement Considerations|
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The DAQ1500 is designed to measure voltages as a ratio of the supply voltage - it is not practical to make measurements of absolute voltages with this product.
For maximum accuracy, all wires from the DAQ1500 to the sensor should be the same length, thickness, and temperature (as the temperature will change the resistance of the wires).
The bridge inputs can be powered down, reducing power consumption with DAQ1500 sensors.}}
{{UGC-Entry|The number I’m getting back from the DAQ1500 is really small|
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Load cells output a small voltage proportional to the amount of strain they are currently experiencing. The rated output for most load cells at full load is in the order of millivolts, so when you’re only straining the load cell at a fraction of its full load, you will get very small values. In order to convert to meaningful units like grams or newtons, you need to [[Calibrating_Load_Cells|calibrate]] the load cell.}}
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