Why is the Scaling I Enabled in MAX Not Working on an Embedded FieldPoint Application? Hardware: FieldPoint>>Analog I/O Modules
Problem: I enabled scaling in Measurement & Automation Explorer under Data Neighborhood»FieldPoint Items»FP@xx_xx_xx_xx»cFP-xx-xxx»Channel 0 with the Scales Tab at the bottom. When I select the cFP Input Module under Data Neighborhood and click on Start, I see the scaling being applied. When I open a Blank VI in LabVIEW 8.0 and read the I/O point on the module, it also shows the correct scaling. Now I create a New Project in LabVIEW 8.0, add the cFP controller as a target and create a new VI under it. I then add a FP Read.vi, select the appropriate I/O point, and hit Run. I see the VI downloading onto the Controller, but the data being read does not reflect any scaling. It's as if it ignored that I enabled scaling in MAX. Why does it behave this way? Solution: Starting with LabVIEW 8.0, communicating with Real-Time targets requries the creating of LabVIEW Projects. If the Real-Time target is FieldPoint, then a separate .iak file is created which is specific to the project. That .iak file is different than the .iak file in MAX or in any other LabVIEW Project. See the screenshot below for more information. When you read the I/O points from MAX or from LabVIEW on the Host machine, it uses the .iak configuration file that you created and modified in MAX. But when you use the Project Explorer in LabVIEW 8.0 and create a VI that is downloaded onto the controller, you need to Enable Scaling on the I/O point inside LabVIEW in the Project Explorer. If the module is controlled by a Compact FieldPoint RT controller, the information is also downloaded to the controller at ftp://ip address/ni-rt/system/fpbank.ini. Related Links: KnowledgeBase 4ALELKMY: What Is the Relationship Between .iak Files, the Project and MAX?
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Report Date: 03/10/2006 Last Updated: 07/01/2008 Document ID: 3V9EHQQG |
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