saludos aki os paso informacion de otro foro sobre cable jtag3 hecho pone los pines correspondencia y como observais no parece que tenga resistencia en el termina que se conecta al receptor este es puerto paralelo ademas hay otro para usb(h***www.simple-solutions.de/catalog/product_info.php?products_id=41)
JTAG Programmer for Zefant modules
[Z-JTAG3] 19,00 EUR
(= 16,38 EUR + VAT)




Click to enlarge
Click to enlarge

WIth this high quality JTAG programming interface you can easily program Xilinx components like FPGAs, CPLDs and BootPROMs with a PC. It is compatible with the Xilinx "Parallel Cable III" (PC3/DLC5) and be used with Xilinx tools like Impact and Chipscope.
The pinout interfaces directly with Zefant baseboards, so only a single connector needs to be plugged in, instead of single conductors for each JTAG signal.
Features
• compatible with Xilinx Parallel Cable III
• high quality: heavy duty metal housing with strain relief
• 1,5m cable length
• GND-lines between signals
• fits perfectly for "Zefant" baseboards and other Xilinx FPGA systems
Pinout
Pin Signal
1 GND
2 VCC
3 TDI
4 TDO
5 TCK
6 TMS
Anwendungsbeispiel

JTAG chain of a Zefant-XS3 FPGA module (Xilinx Impact)
Downloads:

ademas tiene sofware la fotos no ha salido lo siento saludos pasare el de usb esta en (Diigiillentt JTAG--USB Cablle
Refference Manuall
®
www.digilentinc.com
Revision: 3/11/05 215 E Main Suite D | Pullman, WA 99163
(509) 334 6306 Voice and Fax
Doc: 500-053 page 1 of 1
Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.
Overview
The Digilent JTAG-USB Cable provides a
quick and inexpensive USB 2.0 programming
solution for Digilent system boards. The cable
works with any USB-equipped computer and
attaches to system boards using a Digilent 6-
pin JTAG header.
The cable is ideal for notebook computers or
any computer without a parallel port.
It can program any Xilinx device with a
minimum I/O voltage of 1.5V, at speeds up to
ten times faster than a JTAG3 (or parallel 3)
cable.
Features:
• a Digilent 6-pin JTAG header
• speeds up to ten times faster than a
JTAG3 cable
• free JTAG programming software
available
• compatibility with any USB port.
Functional Description
The cable provides an easy and inexpensive
USB connection.
For JTAG programming, the cable’s firmware
drives the JTAG scan chain by transferring .bit
or .svf files. Digilent’s Adept software’s Export
program is needed for JTAG programming.
Export automatically detects devices in the
JTAG scan chain. For more information on
using Export see the Digilent Adept Reference
Manual.
Both the cable and the Adept software are fully
compatible with any Xilinx device on any circuit
board. See the Digilent Adept Reference
Manual for information on programming other
devices.
Before the cable can be used on a given
computer, it must be identified to the Adept
software by adding its serial number or
alphanumeric ID string to the device table in
the Adept software. Every cable is given a
unique serial number and default “DCabUsb”
ID string. The USB administrator tool in the
Adept software can automatically identify a
newly attached cable and add it to the device
table. Once the cable ID is in the device table,
it can be used to configure Xilinx devices.
To download the Adept software and the
Digilent Adept Reference Manual see
www.digilentinc.com.