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Explain type defs

I am new to Labview.  I am using the SPI sub-VI's from the SPI digital waveform library to generate a waveform.  One of the inputs to the VI is a cluster called "Bus Configuration" which contains 3 controls (2 booleans and a numeric control).  This cluster has a "type def" associated with it. 


I am trying to understand the concept of a "type def".  For my VI, I created a cluster with the same inputs as above plus on additional boolean control.  I then unbundle it to extract the fourth control, and re-bundle the 3 controls in the same order to input to the "Bus Configuration" input of SPI  My VI contains the sequence SPI -> SPI -> SPI to create the desired waveform (very similar to the provided SPI example VI).  It should generate 4 waveforms, CS, MISO, MOSI, SCLK.  But when I input the re-bundled cluster into "Bus Configuration" I get an error saying there are only 3 waveforms.  If I use the "Bus Configuration" type def/cluster as a control on my front panel and leave my fourth boolean control separate, then the VI works properly. 


Please explain the proper use of "type def" or is there something else I am doing incorrectly.

Thank you.

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Hi hachena,


I think the LabVIEW help on type definitions should prove useful on explaining the proper use of them:


Also, the “Using Cluster Type Definitions and Cluster Strict Type Definitions” section has information about unbundling them using the “Unbundle By Name” function instead of the “Unbundle” function. Hope this helps.

Bill E. | Applications Engineer | National Instruments
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