The SerialComm TTL-232-33IE is a very high quality and reliable compact industrial-grade bi-directional port-powered RS232 to 3.3V TTL converter which converts full-duplex RS232 to a low voltage 3.3V TTL, This converter is ideal for any demanding application whether indoor in a lab, server room, office, at home or outdoors within the temperature range of -40ºF to 185ºF (-40ºC to 85ºC). The converter is port-powered and derives power by amplifying the RS232 data lines requiring no external power at all but also have the option to add external 5V power. This converter features auto sensing data turnaround eliminating the need for software drivers or handshake flow control. The TTL-232-33IE has a DB9 female connector on the RS232 end, and DB9 male connector on the TTL end. A separate terminal block with no exposed jumpers is included with purchase. The terminal block plugs into the TTL end of the converter, providing screw-lug wire terminations for the port. PORT-POWERED WITH OPTIONAL EXTERNAL POWER The SerialComm TTL-232-33IE has an optional 5V DC external power input, The TTL-232-33IE is normally port-powered from the RS232 data lines while using a capacitor charge pump built into the converter to provide necessary power. There are rare instances where the RS232 host device is not capable of port-powering the converter due to signal incompatibilities or low voltage levels. If this should occur, all that is necessary is adding a 5V DC external power to the terminal block or DB9 connector. Because the TTL-232-33IE is industrial grade and port-powered with an optional 5V power input it makes this converter one of the most versatile RS232 to TTL converters on the market. MEAN TIME BEFORE FAILURE: 306,000 Hours.