How Does the FieldPoint Frequency Measurement Shipping Example Work? Primary Software: LabVIEW Development Systems>>Base PackagePrimary Software Version: 7.0 Primary Software Fixed Version: N/A Secondary Software: Driver Software>>NI-FieldPoint Hardware: FieldPoint>>Discrete I/O Modules>>FP-CTR-500, FieldPoint>>Discrete I/O Modules>>FP-CTR-502
Problem: When I run the FieldPoint shipping example entitled Frequency Measurement.vi, the VI runs once, but it does not appear to plot anything. When I run the example with highlight execution turned on, it appears to be hanging at the FP Advise subVI. What is causing this problem and how can I overcome it? Solution: If the VI appears to hang at the FP Advise subVI, this is most likely due to the fact that the gate is not receiving enough power to output a pulse. This can be corrected by supplying power to the V and C pins of the [c]FP-CTR-50x module, using a separate power supply. It is not a good practice to use jumper wires between the modules or the controller as it destroys the module to module isolation. You will know that the counter module is getting enough power to produce a gate pulse when both the Gate 0 and Output 0 LEDs are blinking. Another commonly encountered problem when using this example involves sinking and sourcing. For more information on sinking and sourcing, please see the links below. The [c]FP-CTR-500 features sinking inputs and sourcing outputs. It is compatible with 12 or 24 VDC devices. The [c]FP-CTR-502 features 5-30 VDC sourcing inputs and sinking outputs. It is compatible with TTL devices and other 5, 12, and 24 VDC devices. Make sure that the signal wired into the counter is the opposite of the input type of that counter. For example, if you are using the [c]FP-CTR-500, the signal whose frequency you wish to measure must be sourcing. Note: Supplying a TTL signal to the [c]FP-CTR-500 will measure a frequency of 0 Hz regardless of the frequency of the signal because the input threshold level for this module are as follows:
Related Links: KnowledgeBase 2HOE7K5F: Understanding Sinking and Sourcing KnowledgeBase 2K0D6H5F: How Do I Connect Two Sinking I/O or Two Sourcing I/O Together? KnowledgeBase 1TB63SUS: Measuring Frequency With the FP-CTR-500/502 Developer Zone Tutorial: Digital I/O Sinking and Sourcing Product Manuals: NI cFP-CTR-500 Manuals Product Manuals: NI cFP-CTR-502 Manuals Attachments:
Report Date: 06/28/2004 Last Updated: 01/03/2008 Document ID: 3ARE14GP |
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