I found this comment in the LabVIEW instrument driver guidelines (section 6.2):
If you need more terminals than the recommended patterns, reconsider the grouping of the controls and indicators on the VI. Except for error in and error out, avoid using clusters to minimize the number of terminals. Clusters often require the user to unbundle and rebundle data from the cluster.
If National Instruments is discouraging clusters, what does ‘reconsider the grouping of the controls and indicators on the VI’ mean?
I really like using clusters, and I think they’ve improved my VIs. Am I missing something?
I think this is probably poor phrasing in NI’s documentation. If it makes sense that a number of different values are written to or read from the instrument or its driver in one go then a cluster is the appropriate data type. You want to try and avoid the situation where the user has to read the data in the cluster out just so they can write it back in with one value changed. The other good general principles for using clusters, certainly in distributable/reusable code like an instrument driver, are:
That way you can change what’s in the cluster without breaking existing code.