LongBow said:
Anyone has any advise on how to send 12V signal from a Barcode Scanner to a PLC?
Thanks
Hi, LongBow. Choose a barcode scanner with RS-232 output, and a PLC
(programmable Logic Controller, an industrial computer with built-in
I/O generally used to run machines) with RS-232.
Most of your difficulty will be in programming the PLC to deal with the
character string and the PLC serial buffers. Sorry, no recommendations
on which barcode scanner to buy. I decided to use a PC in place of a
PLC for that machine the time I tried it. The tradeoffs led me to
decide the additional hardware hassles of a PC would be compensated by
the much easier software route (including drivers from the barcode
manufacturer). Try to pick the easiest way to reliably solve the
machine.
Also, if you're doing it this way, try not to get a free-running
barcode scanner. The PLC serial buffer can be impossible to deal with
when it overruns, and resetting things can take forever. You don't
want this hassle, and you never get the flexibility in a PLC you have
with a PC serial port. Get one that sends data on trigger (either a
button on the scanner, or on a signal from the PLC)as an option. This
is another issue where having a PC instead of a PLC solves a lot of
problems, especially if you've ever programmed serial comm.
Another thing you might want to try is to call the apps engineers at
the manufacturer of the PLC you like. They're usually very helpful,
and frequently will provide sample software for their preferred barcode
scanner.
Questions of this type usually receive a better reception on
sci.engr.control. Try posting there for a lot more advice.
Good luck on your project
Chris