In labVIEW7.1 I wrote a COM port communications driver by using "VISA Write/Read". I put a string as the input of "VISA Write" and made it the input of the whole vi. Then I converted the vi into a DLL, which is called in Teststand3.1 by specifying DLL adapter. In "Edit C/C++ DLL Call" dialog, I pass a message of "60 6A 94 80 86 81" as the input parameter. My problem is I tried three kinds of methods to pass the message, see attached 1.jpg,2.jpg and 3.jpg. and found the first one sometimes doesn't work, the second work fine and the last doesn't work all time. I don't know why the first one and last one don't work well.
Thanks!
Jacky
