What Units Are Returned from C-Series Analog Modules When Using Fixed-Point Data?Hardware: CompactRIO>>Analog Input Modules
Problem: I am using Fixed-Point Data in my FPGA project for my C-series analog modules. What units will be returned with this data? Solution: If you are using LabVIEW 8.5 or later and NI RIO 2.4 or later, you will see calibrated FXP data used with I/O nodes in you FPGA VI. If you are using older versions of LabVIEW or NI RIO, you will see raw integers that need to be converted to either voltage, current, resistance or voltage/voltage using the Binary to Nominal VI. Thermocouple Input Module The NI 9211 is an example of a cRIO thermocouple module. It will read calibrated FXP data from the I/O node in units of Volts. Those voltage readings can then be turned into temperature measurements using the reading from the CJC and knowledge of the thermocouple type. These calculations are shown in the module specific LabVIEW example project NI 9211 Getting Started. RTD Input Module The NI 9217 is an example of a cRIO RTD module. It will read calibrated FXP data from the I/O node in units of Ohms. Those resistance readings can then be turned into temperature measurements using a standard 100 Ohm RTD polynomial conversion function. These calculations are shown in the module specific LabVIEW example project NI 9217 Getting Started.  Strain Input Module The NI 9237 is an example of a cRIO Bridge module. It will read calibrated FXP data from the I/O node in units of Volts/Volts (Channel Voltage/Excitation Voltage). Those voltage/voltage readings can then be turned into strain measurements using knowledge of the bridge configuration (full, half or quarter) and gauge factor. The NI Developer Zone Tutorial: Measuring Strain with Strain Gauges shows the details of such calculations. Current Input/Output Module The NI 9203 is an example of a cRIO current input module. It will read calibrated FXP data from the I/O node in units of Amps. Voltage Input/Output Module The NI 9205 is an example of a cRIO voltage input module. It will read calibrated FXP data from the I/O node in units of Volts. Related Links: Developer Zone Tutorial: Measuring Strain with Strain Gauges KnowledgeBase 4DPGKPKO: How Can I Transfer My Fixed-Point Data Using a FIFO in LabVIEW? Attachments:  LabVIEW Module Specific Examples.PNG
Report Date: 03/24/2008 Last Updated: 12/11/2009 Document ID: 4JNCQO4H |
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