RS232 USB

#954 USB Console Cable

https://www.adafruit.com/product/954

The cable is easiest way ever to connect to your microcontroller/Raspberry Pi/WiFi router serial console port. 
Inside the big USB plug is a USB<->Serial conversion chip and at the end of the 36" cable are four wire - 
red power, 
black ground, 
white RX into USB port, 
and green TX out of the USB port. 
The power pin provides the 5V @ 500mA direct from the USB port and the RX/TX pins are 3.3V level for interfacing with the most common 3.3V logic level chipsets.

UC 232A

http://de.aten.eu/products/Mobilit%C3%A4t-&-USB/USB-Konverter/Konverter-von-USB-auf-serielle-Schnittstelle~UC232A.html

SF9717 USB-TTL 3.3V

http://www.watterott.com/de/TTL-232R-USB-Serial-Converter-33V

Pinbelegung: RTS, RX, TX, 5V, CTS, GND
Logikpegel: 3,3V

The FTDI cable is designed around an FT232RQ, which is housed in a USB A connector. 
The other side of the cable is terminated with a 0.1" pitch, 6-pin connector with the following pinout: RTS, RX, TX, 5V, CTS, GND (RTS is the green cable and GND is  black).

SF9718 USB-TTL 5V

http://www.watterott.com/de/TTL-232R-USB-Serial-Converter

Pinbelegung: RTS, RX, TX, 5V, CTS, GND
Logikpegel: 5V

The FTDI cable is designed around an FT232RQ, which is housed in a USB A connector. 
The other side of the cable is terminated with a 0.1" pitch, 6-pin connector with the following pinout: RTS, RX, TX, 5V, CTS, GND (RTS is the green cable and GND is black).

TTL 232R

http://www.ftdichip.com/Products/Cables/USBTTLSerial.htm

FTDI232

UART-TTL USB Adapter für 3,3V und 5V mit CH340G Konverter und Jumperkabel