Description:
The USB-331 SmartPipe™Protocol
and Code Converter allows RS-232 data to be fed directly into
a USB port as keyboard data. The standard ASCII code set, common
in RS-232 applications, does not correspond to the codes of the
standard USB keyboard, requiring translation between ASCII and
USB keyboard codes. The Vetra USB-331 Protocol Converter performs
these ASCII code to USB keyboard code translations. Additional
keyboards can be connected through an unused USB port on the
computer, or via a hub. Or, use the USB-335
model with an on-board 2-port hub.The connection of a standard
keyboard is optional and not necessary for the USB-331 to operate.
Code Conversion for the USB-331:
The USB-331 SmartPipe™translates
ASCII codes to equivalent USB keyboard codes as shown in the
"ASCII to USB Key Code Translation" Table.
Note that the table contains more codes than the standard ASCII
set. These codes have been added to bring the functionality of
keyboards used with PCs and iMACs into the ASCII world. Simulation
of simultaneous depression of some keys is possible using the
separate make and break codes for the Control, Shift, and Alt
keys, both left and right. For instance, to simulate the Left
Alt and F1 keys combination, hex codes 83, A0, 93 should be sent.
In addition to code translation, the protocol and code converter
also converts voltage and protocol from the asynchronous RS-232
protocol to the USB 2.0 compliant HID device keyboard protocol.
The male DB-9 connector on the USB-331 receives RS-232 data on
pin 2, and controls Clear-To-Send (CTS) on pin 7. Pin 5 is ground.
For an Application Note with more information on need for CTS
and throughput rates in HTML format click here,
or in PDF format. The USB-331 uses
the following RS-232 format: 1 start bit, 1 stop bit, 8 data
bits, and no parity. There
are six baud rates to choose from: 300, 1200, 2400, 4800, 9600
and 19,200 baud.
For a copy of Adobe's Acrobat® Reader |