Item Type: USB to TTL Serial Adapter Line Length: Approx. 50cm / 19.69in Function: USB to TTL Transfer Speed: 300 bps to 1.5 Mbps Port: 5V, 3.3V, TXD, RXD, GND Package List 1 x USB to TTL Serial Adapter The industrial control board has TTL port, which can use a USB to TTL communication cable. Some systems are not compatible. You can use a USB to 232+232 to TTL communication cable. 1Various Ports: Designed to have 5V, 3.3V, TXD, RXD and GND ports to satisfy your varied working needs, reliable and useful. 2Wide Matching: Supports for WINDOWS 98, for ME, for 2000, for XP, for Server 2003, for VISTA, for Server2008, for Win7, etc. 3Has Long Line: A 50cm long cable is also attached to the USB to TTL serial adapter module, which enables firmer connection. 4Better Design: 340 chip has wide compatibility, while the yellow pin header ensures easy installation and good durability. 5Working Light: Comes with PWR, TXD and RXD indicators as well as reserved RTS and CTS positions for convenient operation.