RS232 serial to USB converter

cable for interconnection of USB and RS232 serial interfaces

 USB to serial converter (TTL, not RS232):

Welcome to FTDI - specialists in converting peripherals to Universal Serial Bus (USB).  We offer the easiest route to USB migration by combining USB-Serial (USB-RS232) and USB-FIFO silicon solutions with our ready-to-go royalty free USB drivers.  FTDI's "total" solutions offer reduced development and debug costs and a fast time to market.

PLEASE NOTE - When updating drivers, refer to the following document: AN_107 - Advanced Driver Options

Drivers are available which allow FTDI devices to work with the following operating systems:

• Windows Server 2008 R2
• Windows 7
• Windows 7 x64
• Windows Server 2008
• Windows Server 2008 x64
• Windows Vista
• Windows Vista x64
• Windows Server 2003
• Windows Server 2003 x64
• Windows XP
• Windows XP x64
• Windows 2000
• Windows ME
• Windows 98
• Linux
• Mac OS X
• Mac OS 9
• Mac OS 8
• Windows CE.NET (Version 4.2 and greater) 

For most of these operating systems two types of driver are available:  Virtual COM Port (VCP) drivers and direct (D2XX) drivers.  The VCP driver emulates a standard PC serial port such that the USB device may be communicated with as a standard RS232 device.  The D2XX driver allows direct access to a USB device via a DLL interface.

To locate the drivers you want to install for a device, select which of the driver types you wish to use (VCP or D2XX) and then locate the appropriate operating systems.  With the exception of Windows 98 and Windows ME, all devices are supported in each driver package. 

http://electronics-diy.com/electronic_schematic.php?id=717

USB to RS232 Adapter with FT232 

 We employ two UART boards in the course, one which can be connected to the serial connector of the PC (UART-RS232), and a second that can be connected to a USB port (UART-USB). The former is used in the lab and is part of the standard take-home equipment. The latter is part of the (limited!) number of take-home targets for students who are working on a Laptop without serial connector. In both cases, communication is done with the UART module of the microcontroller. In the case of the normal UART board, the MAX232 simply transforms the voltage levels to RS-232 standards (?3-15V; in our case 12V, with LOW=+12V and HIGH=-12V). In case of the UART-USB, the FT232BM transforms the UART protocol to the USB protocol. This is transparent to the controller, which communicates over the normal TX and RX pins.