what is really meant by Galavanic in " Galvanic Isolation" for isolated IO modules of S800 Series
A "Galvanic" connection is a metal to metal joint. If different metals are joined a galvanic current may flow. This is the principle behind tha galvanic cell or battery.
A "Galvanic Isolation" means there is NO metal to metal contact. The metal contacts are Isolated from each other.