Maxim offers two options that address RS-232 communication where isolation is required. First is the resistive isolated RS-232 transceiver that offers isolation up to ±50V, which eliminates the need for optocouplers for data transfer and a transformer for isolated power. The second option is an RS-232 transceiver chipset that directly drives optocouplers and a transformer, thus simplifying design and eliminating the need for a resistor to bias the optocouplers.
Also see: ESD Protected RS-232 Transceivers
