Reading an ASCII value into RS Logix 500 programming environment

[sukesh_pn]

I am trying to build an inventory management system that receives part numbers(Format, 123-45:67) from a bar code scanner and uses Allen Bradley 1100 PLC to keep a track of parts in stock . I require some help/hints on programming steps, to detect when there is a new bar code scan; write the value (part number) in Channel 0 into a string and clear buffer for next bar-code scan. I do understand that key is to use ARL instruction but I am not able to figure out how to trigger a false to true transition for the same, as there is no traditional input in this case.

 

[drbitboy]

An [XIO R6:n.EN] bit of the control on the rung feeding the ARL should cause the ARL to repeat (not sure about startup, though; it many need to be ANDed with [XIC S:1/15] i.e. first pass.


Another option would be to run a timer, fed by a [XIO R6:n.EN], which would repeat but would provide a delay between runs of the ARL.


Caveat

• these are rough ideas; thay may not even come close to working
• the code should also react intelligently to the .ER bit becoming 1 e.g. reset the ARL.