System Exec.vi

[Chris Cartwright]

Hi folks,

Does anyone know what happens behind the scenes in the external code call in the "system exec.vi". There is a reference to "systemexec.lsb" file inside the VI that NI used at design time.

It appears to call a DLL type function - but where is it? Is it a real DLL somewhere on the PC, or encoded within the vi itself?

Any help greatly appreciated!

Cheers,

Chris.

[Yair]

It's called a CIN (Code Interface Node) and is a way to embed C code into your VI.

I'm not sure exactly when the C code is compiled, but you should be able to find more info in the LV help for the CIN.

It's older technology only left around for compatibilty, so you should not use it yourself.

[crelf]

QUOTE(yen @ Apr 22 2007, 05:15 AM)

(Code Interface Nodes are) left around for compatibilty, so you should not use it yourself.

Really? Why?

[Yair]

Actually, that was just because Rolf keeps saying it, but looking in the LV help you can find

QUOTE

National Instruments recommends using a shared library (DLL) rather than a CIN if you want to use a language other than C or C++. LabVIEW does not support the creation of external subroutines. If you want to share code among multiple CINs, use DLLs.

and

QUOTE

To create a CIN, you must be an experienced C developer. Also, because CINs are tightly coupled with LabVIEW, restrictions exist about which

compilers

you can use.

It also says that

QUOTE

CINs have the following advantages:

• The CIN code is integrated into the code of the VI, so there is no extra file to maintain when the VI is distributed.
  
  
• CINs provide certain special entry points, such as CINLoad, CINSave, and so on.
  
  

[crelf]

QUOTE(yen @ Apr 22 2007, 07:25 AM)

...looking in the LV help you can find...

Thanks for the info yen :thumbup:

[Rolf Kalbermatter]

QUOTE(crelf @ Apr 21 2007, 05:08 PM)

Thanks for the info yen :thumbup:

You can also read the first post in a row of posts to come about LabVIEW external code at

http://expressionflow.com/external-code-in-labview-part1-historical-overview/' target="_blank">http://expressionflow.com/external-code-in...rical-overview/ to get an idea about what CINs and CLNs are about, why they exist and why you should use CLNs instead of CINs nowadays.

Rolf Kalbermatter