Rockwell Automation 1734-485ASC POINT I/O ASCII User Manual - Manual (Page 65)

Publication 1734-UM009B-EN-P - July 2003
Using the ASCII Modules with the ControlLogix System Application Examples B-5
The following ControlLogix ladder logic checks to see if the
transaction ID in Local:1:I.Data[0] has changed from a previously
stored value. If it has changed, the data starting in Local:1:I.Data[4] is
copied to a file and the current ID is stored into a data location.
If data is being received quite often, we recommend storing the
receive data into some kind of large rotary buffer so as not to
overwrite an older packet before it is decoded.