PassMark Software
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USB Loopback Plugs

High quality, loopback plugs for USB troubleshooting and USB testing.

This product has been discontinued and is no longer for sale. The replacement products are the USB 2.0 loop back plug and the USB 3.0 loopback plug. This old information remains here for support purposes

USB Loopback plugs can be used to help diagnose, troubleshoot and load test your PC.

When used with the BurnInTest Professional software package V4.0 or higher and USB2Test Software, it is possible to:

USB Loopback plug - Click for larger imageActive loopback plugs are the quickest, most effective way to verify that a PC's USB ports are working correctly. The Red, Green and Yellow LED's on the front of this USB adapter plug provide a quick visual indication of I/O activity and if the USB bus is powered. This will dramatically improve the troubleshooting and diagnostic ability of computer technicians and system integrators, who have previously been working blind.

For reliability and load testing, error free transfer speeds of around 95 - 100 kbytes/sec per plug can be expected on a system that is functioning correctly. Up to 10 of these USB test plugs can be simultaneously connected to a PC (providing that free USB ports are available on the PC or on a down stream hub).

These plugs are unique! They are the only true USB loop back adapters on the market and have been especially designed for use with our BurnInTest Professional software package. They do not require an external power supply and do not require a connection to any other port on a PC. Each plug also has its own serial number stored in EPROM, on the plug, so it is possible to identify each plug when multiple plugs are connected.

Technical Specifications

USB standard: 1.1 (but is forwardly compatible with USB 2.0)
(See also USB2.0 plugs)
Plug and play: Compliant
Physical connector: Standard 4 wire USB
(2 x Balanced Signal, 1 Voltage [VBUS], 1 Ground [GND])
USB Transfer modes: Bulk
Voltage: 4.625V - 5.25V, Typical operation. (No external power supply is required)
Current: 90mA (typical operation)
Clock speed: 6.00Mhz input to x8 multiplier
Device buffer: 384 bytes Rx, 128 byte Tx
Case: High impact MABS plastic
Size: 65mm x 50mm x 20mm (2.5 x 2.0 x 0.8 inches)
Weight: 30.5g (1.1oz)
Indicators: Red LED = Power
Green LED = Transmit data
Yellow LED = Receive data
EMC standards: AS/NZS 3548:1995, EC
Storage Temperature: -20 ºC to + 70 ºC
Usage Temperature: 0 ºC to + 50 ºC
Max speed: 12 Mbits/sec
Model PMUSB01


This product has been discontinued and is no longer for sale. The replacement product is the USB 2.0 loop back plug. This old information remains here for support purposes

Self powered. Even with low power portable USB portsCabling

The USB cable was not sold with the plugs. You will need to supply your own standard USB cable. While just about any USB cable will work, it is better to select a quality full speed, shielded, USB cable when testing. Note that some of the cheaper USB cables are not shielded and thus are not recommended. The cable must be shorter than the 5m allowed in the USB standard. If a USB connection is required beyond 5m one or more hubs are required to extend a USB connection.


Window 98, ME, 2000 and XP are supported.
Window 95, NT4, Mac & Linux are not supported.
In order to use the plugs BurnInTest Professional version 2.6 or above is required.
USB 1.1 and 2.0 ports are supported. (when connected to a USB 2.0 port only the lower speed, USB 1.1, mode will be used).

** Only suitable for BurnInTest v4.0 and above. A program such as WinZip is required to uncompress these files.
** The Adobe PDF viewer is required to view these files.

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