Vetra Systems Corporation
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Vetra Systems manufactures a complete line of KVM products and solutions

VIP-335 RS-232 to PS/2 Keyboard Protocol Converter Convert RS-232 Serial Data to PS/2 Keyboard Protocol with the VIP-335 "Smart-Pipe"


The VIP-335 “SmartPipe”™ Protocol Converters allow RS-232 data to be fed directly into a PC’s keyboard port. A standard keyboard can also be connected to the “SmartPipe”, and its output will be merged with the RS-232 data forming a keyboard wedge. The keyboard is optional and is not required for the VIP-335 to boot up and operate with the PC.

Code Conversion for the VIP-335

The standard ASCII code set, common in RS-232 applications, does not correspond to the scan codes of the standard PC keyboard, requiring translation between ASCII and PC keyboard codes . The Vetra Protocol Converters offer switch selectable ASCII code to keyboard scan code translation.

With code translation enabled, the VIP-335 “SmartPipe”™ translates ASCII codes to equivalent PC keyboard scan codes as shown in the "ASCII to PC 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 the PC keyboard 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. For instance, to simulate the Left Alt F1 keys combination, hex codes 83, A0, 93 should be sent.

With code translation disabled every character received at the input of the Converters is copied unaltered to the output. The converters do only a voltage and protocol conversion between the PC’s bit synchronous TTL level protocol, and the asynchronous RS-232 protocol. The user is responsible for generating RS-232 data that is meaningful to the PC’s keyboard input. The DB-9 connector on the VIP-335 receives data on pin 2, and controls Clear-To-Send (CTS) on pin 7. Pin 5 is ground. For more information on CTS behavior click here.

The VIP-335 uses the following RS-232 format. 1 start bit, 1 stop bit, 8 data bits, and no parity. There are four baud rates to choose from 1200, 2400, 4800, and 9600 baud.


  • Designed and manufactured in the USA for use around the world
  • Backed by a Limited 3 Year Warranty
  • Compatible with all popular keyboards and all operating systems
  • Error free boot-up for all connected devices
  • Custom versions available


VIP-335: Accepts RS-232 input and converts it to PC Keyboard scan codes. Also allows a standard PS/2 keyboard to be wedged into the PC's keyboard port.

Same functions as above, but is assembled PCB only (has no housing). Size of the PCB is 4.1 in x 4.785 in (10.4cm x 12.15 cm). Click (here) for detailed PCB dimensions.
$119.00 tab_blue_button_add.gif

All prices subject to change without notice.
For International Representatives click here.



A standard 6 pin mini-DIN male - male extension cable, provided with the units, is used to connect the VIP-335 Protocol converter to the keyboard port of the PC (no cable is provided with the VIP-335-OEM). A cable terminated in a standard DB-9 female connector is required to interface RS-232 data to the converter. Vetra offers a selection of DB-9 cables, see Accessories. The captive cable of the keyboard is used to connect it to the VIP-335 Protocol Converter. Adapters are available for keyboards and / or PCs utilizing 5 pin DIN connectors, see Accessories.


Dimensions for the VIP-335 Protocol converter are 1.5 in H x 5.08 in W x 5.25 in D (3.81 cm x 12.90 cm x 13.34 cm). For dimension data for the VIP-335-OEM click here. The housing is molded of black GE Cycolac-T, a high impact ABS material, and is internally shielded with an acrylic base nickel coating for RFI attenuation. Front and rear panels are fabricated from .062 in thick aluminium and finished with low gloss black paint. FCC and CE marked. Shipping weight is less than 2 lbs per unit.

 Environmental Operating Temp:
Storage Temp:
5 to 104 deg. F (-15 - 40 deg. C) 
-4 to 122 deg. F (-20 - 50 deg. C)
 Supported Hardware Computer:
IBM PC/AT, PS/2 and 100% compatibles
AT and PS/2 keyboards
SmartPipe is a trademark of Vetra Systems Corporation, Copyright © 1995-2004 by Vetra Systems Corporation, All Rights Reserved

For user instructions for the VIP-335 click here.
For user instructions in PDF format.

For a copy of Adobe's Acrobat® Reader.


 All Vetra Systems products are proudly designed and manufactured in the USA for enterprise mission-critical applications and are backed by a Limited 3 Year Warranty

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 VETRA Systems Corporation
275 Marcus Blvd. Ste-J Hauppauge, NY 11788-2022 USA
Toll Free 1-800-537-9296
Tel: 631-434-3185 Fax: 631-434-3516 e-mail: