Load Cell Data Acquisition Reference Example with Null Offset and Shunt Calibration
PrintOverview
This example shows how to acquire load cell data, along with performing null offset and shunt calibration if desired.
Downloads
Filename: load_cell_null_off_shuntcal.vi
Requirements: View
This VI, combined with the NI 9237, is designed to be an out of the box solution to acquire load cell data. Minimal inputs are required (Physical Channels, Excitation Value, mV/V, and Max Weight) for operation, while functionality for Offset Nulling and Shunt Calibration can be enabled or disabled as desired. Enabling Offset Nulling will account for any offset before starting acquisition, essentially making your initial value zero. (Please have the load cell at an idle (resting) state before starting the VI). Enabling Shunt Calibration will connect the internal 100k resistor of the NI 9237 to the load cell, therefore obtaining an even more accurate reading. (Note: When Shunt Calibration is enabled, please fill in the values for 'Shunt Calibration Parameters' appropriately).
Note: It is assumed that the load cell type is full-bridge completion.
Note: Although the 9237 can use external excitation for the load cell, this example uses internal excitation. Excitation options for the NI 9237 are 2.5V, 3.3V, 5V, and 10V. Max excitation power is 150mW.
9237 Operating Instructions and Specifications
Note: This was designed for the NI 9237, using LabVIEW 8.5 and NI-DAQmx 8.7.1. NI-DAQmx 8.7.1 or above is required, as the example program attached uses VI's which are not present before 8.7.1.
**The accompanying code represents a very specific use case for NI products. For more general examples, please refer to ni.com/examples, the LabVIEW Example Finder, or the NI driver help files that come with every NI driver.
Requirements
Filename: load_cell_null_off_shuntcal.vi
Software Requirements
Application Software: LabVIEW Base Development System 8.5, LabVIEW Professional Development System 8.5, LabVIEW Full Development System 8.5
Language(s): LabVIEW
Hardware Requirements
Hardware Group: CompactDAQ
Hardware Model: USB-9237, NI 9237
Driver: NI-DAQmx 8.7.1
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This example program (this "program") was developed by a National Instruments ("NI") Applications Engineer. Although technical support of this program may be made available by National Instruments, this program may not be completely tested and verified, and NI does not guarantee its quality in any way or that NI will continue to support this program with each new revision of related products and drivers. THIS EXAMPLE PROGRAM IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND AND SUBJECT TO CERTAIN RESTRICTIONS AS MORE SPECIFICALLY SET FORTH IN NI.COM'S TERMS OF USE (http://ni.com/legal/termsofuse/unitedstates/us/).