constant means?

[Isabella]

Hi All, I would like to ask what does the constant means? Sorry that i'm quite new to labview. Thanks. Regards, Isa

[JK1]

Hai,

Find attached the image in which the constants are represented in red.  Constants are one whose value does not change or cannot be changed programmatically.  Its just similar to the constants that are used in any text based programming language.

In LabVIEW string, numeric, array, file path,  cluster , Enum, Ring, Time stamp constants are the basic constants type available (Many more constants are available but these are basic and used in common).

Feel free to post any doubts. 

Message Edited by JK1 on 01-07-2009 09:45 PM

[Isabella]

Hi,

But what does the array constant means that connected with the shift register? Clear the value?

Thanks & Regards,

Isa

[RavensFan]

Yes. The array constant (it is an empty 2-D string array) provides the initial value for the shift register and iteration 0 before the loop is run. After each iteration of the loop, the shift register will contain what ever value goes into it on the node on the right hand side of the loop. If that array constant didn't exist, then the shift register would contain whatever value remained from the last time the loop was run, even if you stopped and restarted the VI as long as it remained in memory (which is a useful feature needed for functional global variables or action engines)

Message Edited by Ravens Fan on 01-08-2009 12:29 AM

[JK1]

Hai,

A 2-D string array is just similar to declaring a 2-D array in other languages.

Wiring a 2D string array constant initializes the shift register with the predefined values in the array.

Wiring a empty array constant means initializing the shift reg with empty 2D array or simply clearing the contents of the shift register.

If the empty array constant  is not wired then shift register keeps accumalating the values during each run of the VI even if the VI is stopped and restarted until VI is closed.

Hope this helps.