2744461 - 

The RS-232 interface is an asymmetrical voltage interface (common signal earth for all signals). In addition to a very low signal output, the interface is characterized by the signal earth being connected to the ground chassis housing. The consequence is very low interference resistance and a range of a maximum of 15 m. A considerable increase in the interference-resistance in industrial applications can be achieved by the use of RS-232 isolator modules. The high-grade 3-way isolation between both interface sides, supply and ground potentials provide a floating and interference-resistant RS-232 interface. The positive side-effect: The expensive terminal equipment is also protected from damage by this decoupling.