MVM ...masked move

can someone give me a plain english explaination of the MVM instruction and when to use it properly ...thank you ...

In plain English, it moves bits from one location to another, but instead of moving all of them, it moves only ones you want to move, depending on which ones you hide (mask).

Uses vary, but I've used them when I have an 16 input card that contains a binary coded decimal on four of the inputs, and the other inputs are unrelated sensors. I use the MVM to move the BCD information into a separate file to use later in the program.

Edit:
I think I might have just done someone's homework without thinking

Welcome to the Forum.
The MVM instruction is a digital "strainer"; depending of the state (1 or 0) of the individual bits of the Mask word, the MVM will either move the state of the Source's any bit within the Destination word corresponding bit(if the Mask's corresponding bit is 1-TRUE) or not pass it if the Mask's corresponding bit is 0-FALSE.
The user is able to "restrict" any bit state transfer between Source and Destionation by simply turning the corresponding bit of the Mask to 0-FALSE and then, turning the Mask bit ti 1-TRUE when the "restriction" is not needed anymore.

see if the three posts which start here will help ...

http://www.plctalk.net/qanda/showthread.php?p=52885&postcount=10