RS232 Medical Isolator I1 The RS232 Medical Isolator disconnects every electrically conducting connection (specifically the data and shield conductors) between devices connected together via a serial interface cable. The isolator prevents current flow resulting from differences in electrical potentials, and also protects connected devices and their users from stray external voltages and power surges which may be directly or inductively coupled onto the network lines by causes such as installation errors, lightning, switching operations, and electrostatic discharge.