Archived: Load Cell Data Acquisition Reference Example with Null Offset and Shunt Calibration

[ExamplePrograms]

Description

Description-Separate-1

Overview

This document has been archived and is no longer updated by National Instruments.

This example shows how to acquire load cell data, along with performing null offset and shunt calibration if desired.

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.

Description-Separate-2