Voltage Signal From Gain Module is Not Amplified in MAX When Gain is Set.Hardware: SCXI>>Modules>>SCXI-1141
Problem: Why do I see an unamplified voltage signal in LabVIEW and Measurement and Automation Explorer (MAX) when I set a gain in MAX for my SCXI or SCC amplifier module? Solution: You should not see the applied gain in MAX. Your SCXI or SCC module is not damaged because MAX shows the same voltage applied to the input of the gain module. Rather, the gain module works by amplifying the voltage signal before it goes through the analog to digital converter. The driver then takes this measurement and scales it back down by the gain applied by the amplifier before it is displayed to the user. Because the amplifier module is configured in MAX, the driver “knows” by how much to scale the gain back to the original voltage value. This is why the user only sees the unamplified signal in LabVIEW and in MAX. This is done to obtain a better resolution for the given input range of the DAQ card. One would not use an amplifier module just to see the voltage multiplied by X when it is displayed to the user. For this, one could simply use a scale that would multiply the voltage to the desired range. The purpose of a signal conditioning amplifier is to make a small analog signal fit within the range of the DAQ card before it is converted to a digital value. This takes better advantage of the DAQ card’s resolution and creates a more accurate digital value after the analog to digital converter. The driver provides the added convenience of not worrying about the applied gain allowing the user to work with a more accurate reading. Related Links: SCXI & Signal Conditioning Support KnowledgeBase [1ABBOQVK]: How Do I Set the Gain for My Analog Input Channels in LabVIEW? KnowledgeBase [2MDI2SH5]: Why Can't I See the Applied Gain of an SCC Module in the Measurement and Automation Explorer Test Panel? Attachments:
Report Date: 03/31/2004 Last Updated: 09/19/2006 Document ID: 37MDGSLZ |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
