Continuous Analog Input with Offset and Shunt Calibration on an SCXI-1121 Module
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This example VI performs offset null compensation and shunt calibration on a strain virtual channel configured for the SCXI-1121 module. This example VI also performs a continuous acquisition of the calibrated channel, adjusting each measurement appropriately for maximum accuracy. It plots the strain measurements to a chart.
There are two options for calibration possible in this program. One option is to simply enter an offset and gain adjust factor to use for software calibration. Use this option to save time when you want to enter calibration information from a former calibration process. This option saves time and NI recommends that you perform the calibration each time you run this program for maximum accuracy.
The other option is to manually perform a hardware calibration, and compute the offset and gain adjust factors necessary for a software calibration of the channel. This option provides maximum accuracy, and is the recommended mode of operation.
In order to perform an the offset null compensation this program relies on both a hardware and software adjustment. The program allows customers to adjust a screw potentiometer on the front of the SCXI-1321 terminal block until the measurement is as close to 0 as possible. When you have have determined that this manual offset null is complete, the program then determines the residual offset, and subtracts this from each future measurement. This is called the offset adjustment factor. Using this combination of hardware and software method, the offset null compensation is optimized.
The example VI also performs a shunt calibration by programmatically engaging shunt switches, then performs calibration math, and returns a gain adjustment factor. In order for this portion of the example to work correctly, you must have the correct values for the strain system setup in the VI controls. Also, the order that you call the functions is critical for correct operation. If you change the order that you call the subVIs in the example, most likely the program will not function as expected.
By performing an offset null compensation and shunt calibration using this example VI you can dramatically increase the accuracy of the measurements. This example is intended only for use with the SCXI-1121 with the SCXI-1321 terminal block. It is intended to work with NI-DAQ 6.9.x or Traditional NI-DAQ 7.0.
Filename: 2261.llb
Application Software: LabVIEW Full Development System 7.0, LabVIEW Full Development System 7.0
Language(s): LabVIEW
Hardware Group: SCXI
Hardware Model: SCXI-1121
Driver: Traditional NI-DAQ (Legacy) 6.9.0
There are two options for calibration possible in this program. One option is to simply enter an offset and gain adjust factor to use for software calibration. Use this option to save time when you want to enter calibration information from a former calibration process. This option saves time and NI recommends that you perform the calibration each time you run this program for maximum accuracy.
The other option is to manually perform a hardware calibration, and compute the offset and gain adjust factors necessary for a software calibration of the channel. This option provides maximum accuracy, and is the recommended mode of operation.
In order to perform an the offset null compensation this program relies on both a hardware and software adjustment. The program allows customers to adjust a screw potentiometer on the front of the SCXI-1321 terminal block until the measurement is as close to 0 as possible. When you have have determined that this manual offset null is complete, the program then determines the residual offset, and subtracts this from each future measurement. This is called the offset adjustment factor. Using this combination of hardware and software method, the offset null compensation is optimized.
The example VI also performs a shunt calibration by programmatically engaging shunt switches, then performs calibration math, and returns a gain adjustment factor. In order for this portion of the example to work correctly, you must have the correct values for the strain system setup in the VI controls. Also, the order that you call the functions is critical for correct operation. If you change the order that you call the subVIs in the example, most likely the program will not function as expected.
By performing an offset null compensation and shunt calibration using this example VI you can dramatically increase the accuracy of the measurements. This example is intended only for use with the SCXI-1121 with the SCXI-1321 terminal block. It is intended to work with NI-DAQ 6.9.x or Traditional NI-DAQ 7.0.
Requirements
Filename: 2261.llb
Software Requirements
Application Software: LabVIEW Full Development System 7.0, LabVIEW Full Development System 7.0
Language(s): LabVIEW
Hardware Requirements
Hardware Group: SCXI
Hardware Model: SCXI-1121
Driver: Traditional NI-DAQ (Legacy) 6.9.0
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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/).