Hi Valen,
It does look like you're having a similar problem to what I was having.... I was using LV6.0 at the time.
Basically, when the while loop is executing, you are trigerring on the fact that there is an appropriately long string available to be processed, but by the time it is ready to be processed, the info is gone. My work around (if I recall..) was to place a shift register and append whatever string was captured and feed it to the shift register. The output of the shift register was then passed to the next step for processing. Otherwise, the string was always "dissappearing". I think it was because it was processing the value in the next iteration, whuich means that the barcode data got captured, the while loop does an iteration, then sees the data, but since it was in another iteration, the scanner was read again and filled the string with its new value which was an empty string (it had not read something new). Then this new value was passed from the while loop.
I know, the above doesn't make sense.... how do I describe that better.... Hummm.... the best way is to probe the data while highliting the execution, you'll see what happens.
Remember, you are reading the device at all times. like the keyboard, for instance... if you don;t type anything, nothing appears on the screen. But it doesn't mean that the keyboard buffer is not being read.. So in the while loop, you are reading (looking at the value) of the string for every iteration, whether there is data or not. So, once you actually trigger on the fact that there is data, the data is now flowing and the string "buffer" is filled with whatever the scanner now scanned, which is typically nothing. So that becomes the new data... or at least in the scenario that I had when first playing with scanners.
Appaending all new data permitted the loop to conserve past data which included what was recently scanned. I then parsed the data before processing it.
For what I was experiencing, the idea was that either I kept the last barcode capture or processed the data within the same iteration of the while loop. It's been a while since I worked with barcode scanners, but the last time I programmed a vi for it, I basically place a delay greater (slightly) than the time for the scanner to process the scan and append whatever is captured onto a single string which is parsed before processing. Worked great with the wedge types..
Sorry the explanation is strange... I probably have need for more cafeine!! 😉
Hope it does help you. But from what you describe, it sounds very familiar.. 😮
😄
JLV
Message Edited by JoeLabView on 04-19-2006 02:03 PM
