How to transfer string from to PV600 and CompactLogix 1769

What I am triying to do is to transfer and display on the PV600 values stored in strings on the PLC, and viceversa being abble to doing text input on the PV600 store the values on the PLC.

I have worked before using de Logic Mapping to do this with binary and INT values but never using strings.

How can I do this, and what would be the length limit for these strings?

Thanks in advance,

Edwin