Model 4866 gives true IEEE-488.2 compatible GPIB interface for serial device by intercepting and responding to all IEEE-488.2 commands. It also responds to 4 SCPI root words for self-control of setup. IEEE-488.2 and reserved SCPI commands are blocked from serial device. All other messages pass on. Responses are then output on GPIB bus when 4866 is addressed to talk. Smart GPIB to Serial Interface works with all types of serial devices and includes RS232 and RS422 signals.