So we’ll call this “basic voltage” and this “basic passed.” A line across the top and make a copy. Let’s say the pieces of data we want are this: four simple pieces, this voltage for each test and then whether that test passed or failed. What we really want is an instance of a type definition in all cases, so I’ll right click on the border and make this a type def, and open up the type def, save it, keep the same prefix and choose “data.” Let’s make this a little prettier, expand this a bit. Now right here we’ve kept the data pretty simple: numeric and boolean and we haven’t even been terribly consistent about the labels, so let’s change that. We’ll go back here, get rid of this and instead the data is going to more closely reflect what’s in here. So what I really want is one shift register that holds all of those and so we’ll keep them in a cluster.

Well now then I have four different shift registers sitting here and pulling them off, and as you can imagine as my application scales I’d have a bunch of these, that’s inconvenient. Now what should I put in here? Well this “passed” is a boolean, so I could go and wire this boolean into here, but then what about the data for the advanced test? I can’t use the same shift register because that’ll be a different value so I’d have to create another one and then what if I also wanted the actual values for the test? Maybe some voltage values, maybe for both tests.

Well I’ll right click and create a shift register. In this case let’s say I want to pass the data regarding the basic test from this state to the notify state. Are your ears perking up? Because that’s what a shift register is for and that’s what we’re going to use. In other words, how do we get data between states? Within a state it’s pretty easy, we just pass the data to whatever handles it, but getting it from this state over to this state will require passing that data between loop iterations. In our last episode we took a look at implementing error handling in our state machine and we asked a question at the end: if, for instance, I’m going to notify the user of whether a test passed, how does the notify VI know which test passed? It may be values for the test if the tests occur in other states. įollow us at all these fine destinations: Want to learn LabVIEW? We can help with Sixclear Lucid LabVIEW Fundamentals Training at. We’ll show how to notify the user of the test results as well. We’re almost finished with state machines, and this time we discuss how to pass data between states by making a type defined data cluster and using a shift register. VI High 56 - How to Pass Data Between States in a LabVIEW State Machine - pt 1

Labview shift registers