LabVIEW
Tips and best practices for translating C into LabVIEW? SERIOUS newbie...
You might be getting hung up on front panel controls and front panel indicators. If you are creating a function where you would like to compute a value (Input 1 in your example) from 3 inputs
double myFunc(double input1, double input2, double input3) { result = input2 * (input 1 + input3); }
then you would create a vi with input1, input2, and input3 controls on your front panel, and one indicator called something like myResult. On the block diagram, the controls are sources that you can read out, and the indicators are sinks where you write values. You can create something called a Local Variable (possibly an abomination in LabVIEW) where you can write to a front panel control and read from a front panel indicator too.
LabVIEW is a dataflow programming language and the concept of variables is analogous with wires on the block diagram, however, you cannot read and write to a wire. It will take a while for you to get your head around this (trust me 
) but it will come. As soon as you start doing multi-threaded parallel applications by simply drawing another while loop on your block diagram you will start to smile.
You are correct in that the Value for Input1 is a separate entity from Input1. In this case, Input1 is a control. Value for Input1 is an indicator. However, the two values themselves are equivalent. In that I mean the values are the same. Input1 is a variable. The reference to Input1 is the address of that variable. By using the Value property node, I read the data at that address and transfer it into the indicator called Value for Input1.
To write to the control, right click on the property node and select Change to Write. When first created, the property node comes up in a read mode, meaning you can read the data value at the referenced address. By right clicking and selecting Change to Write, the property node changes direction and accepts an input. This input will be written to the address space, effectively changing the actual value of Input1.
promba wrote:OK, here's another example:
Input1 = (Input2 * (Input1 + Input3));
Is there a way to assign input1 and reference input1 in LabVIEW? Or do I need some other temporary variable? When I try to wire the output of the "*" operator into Input1, I get an error.
Thanks!
This code construct MIGHT typically be inside a loop and in that case it would be best solved with a shift register inside the loop.
Another way to do this if it is not inside a loop is using locals (I don't advice to use locals much but they still are much better than control references). You basically take the control terminal as input and write the result back into a local of that control.
promba wrote:OK, here's another example:
Input1 = (Input2 * (Input1 + Input3));
Is there a way to assign input1 and reference input1 in LabVIEW? Or do I need some other temporary variable? When I try to wire the output of the "*" operator into Input1, I get an error.
If you loop back to the control you'll get an error, yes. You'll need to use a local variable or just continue the result wire.
That's the easy to use and understand version, probably the ending local variable isn't needed. If it's used later on you can simply wire directly there instead.
If this is supposed to be a function you'll run into the problem of Inputs cannot be outputs, the solution is simply to create an indicator Output 1 instead.
/Y
