I have a VIVO LS-6090 barcode scanner with a USB connector, an Arduino UNO and an Arduino USB shield. Can I program the Arduino to trigger the scanner and put the scanner output into a file for analysis? The only programming information I have is in the getting started book written for the Arduino IDE. Are there more instructions required to control the USB shield in this IDE?
Hi,
Welcome to the forum.
Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html
Can you post a link to the specs/data of the USB shield please.
Thanks.. Tom... 
How are you planning on starting the scan? Does that scanner Support a scan command from the USB port? Or are you planning on doing your own Hardware and have the Arduino "press the trigger"?
Depends on your scanner if that can work. The putting the scanner output to file part, no problem. Just add a (micro)SD storage to it.
Going back to the beginning: I thought of a bar code scanner as a way of distinguishing one model train from another and depending on the bar code stuck to the roof of the loco setting the points to main or branch line.
The USB shield is the shield sold by Arduino to piggy back on the UNO or mega boards.
As to triggering I believe the scanner I bought has an automatic detection BC-6000S but I have yet to figure out how that works. The scanner is the LS-6090 from VIVO.
If somebody can suggest a simpler way of distinguishing between 3 or 4 model trains as they pass I'm happy to bin the scanner and try something else.
This topic all of a sudden becomes a lot more interesting I think you now posed the correct question (you may want to update your subject to something like "how to identify model trains" as it's what you really want).
RFID comes to mind, but don't know if that can be done on the cheap. You'd need an RFID reader and each train its own RFID token that's read when it passes by.
A more old-fashioned way: three reed contacts, pattern of magnets under the train. When the third reed is triggered, read reed 1 and 2. Four trains, four binary codes: 00, 01, 10 and 11. Should work find at slow speeds, magnets maybe 3-5 cm apart. Add reeds at other parts of the rail if you want to see when a train passes by.