Document Reference No.: FT_000116
USB TO RS422 SERIAL CONVERTER CABLE Datasheet
Version 1.2
Clearance No.: FTDI# 74
1 Description
The USB-RS422 cable is a USB to RS422 levels serial UART converter cable incorporating FTDI’s
FT232RQ USB to serial UART interface IC device which handles all the USB signalling and protocols. The
cable provides a fast, simple way to connect devices with a RS422 interface to USB.
Each USB-RS422 cable contains a small internal electronic circuit board, utilising the FT232R, which is
encapsulated into the USB connector end of the cable. The FT232R datasheet, DS_FT232R, is available at
http://www.ftdichip.com. The integrated electronics also include the RS422 transceiver plus Tx and Rx
LEDs which give a visual indication of traffic on the cable (if transparent USB connector mould specified).
The other end of the cable is bare, tinned wire ended connections by default, but can be customised
using different connectors to support various applications.
Cables are FCC, CE, RoHS compliant.
The USB side of the cable is USB powered and USB 2.0 full speed compatible. Each cable is 1.8m long
and supports a data transfer rate up to 3 Mbaud. Each cable supports the FTDIChip-ID™, with a unique
USB serial number programmed into the FT232R. This feature can be used to create a security or
password protected file transfer access using the cable. Further information and examples on this feature
are available at http://www.ftdichip.com under FTDIChip-ID Projects.
The USB-RS422 cables require USB drivers, available free from http://www.ftdichip.com, which are
used to make the FT232R in the cable appear as a virtual COM port (VCP). This then allows the user to
communicate with the USB interface via a standard PC serial emulation port (for example TTY). Another
FTDI USB driver, the D2XX driver, can also be used with application software to directly access the
FT232R on the cable though a DLL. This is illustrated in the Figure 1.1
Various Connector
Options
Wire Ended
USB_RS422
TTY
Customised connectors
USB
Virtual COM Port
Various Connector
Options
Wire Ended
TTY
Customised connectors
USB
Software application access to USB via D2XX Driver
Figure 1.1 Using the USB-RS422 Cable
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