USB2Test many device transceiver errors

[loondawg]

Can anyone lend any insight into how to address high numbers of device transceiver errors? Or even what they mean? Or should I be concerned since the system seem to operate okay most of the time.

I recently purchased on the USB 2.0 loopback testers. And I get a very high number of device transceiver errors on the loopback test. I have tried both front and rear ports with a wide variety of cables. The results seem about the same regardless of the combinations used it averages about 3 times the number of operations. 73 ops = 244 errors, 5046 ops = 16947 errors. And there are no verification errors.

And when I run the benchmark test, it seems to run fine. It gives an average data rate of around 350 Mb/s.

I've had various USB devices running from these ports with generally good operation. There have been some slowdowns but I can't rule out other hardware or software factors yet. Although the slowdowns are inconsistent, the USB tests seem very constant.

When I can, I want to try this on another PC to see what happens. I the meantime, can anyone offer some advice about what I am seeing on this computer?

[Ian (PassMark)]

It is normally an electircal interference issue. If you have tried other high quality short cables, then you might also try removing your other USB devices from the bus to see if one of these is causing this behavior. If you were connecting behind a hub, then you might try directly connecting to the motherboard. If the problem was only occuring more-so on the front header plugs, then you could check that the internal header cables were properly seated on the motherboard.

From our support page:
"It means the USB 2.0 loopback plug has flagged a Device transceiver error. Device transceiver errors are triggered when the USB transceiver on the USB 2.0 loopback plug detects what it considers to be an error. These are events at a low level that may lead to the packet being retransmitted. They do not represent data errors at the application level. These errors are normally not visible to the user, but are displayed to help identify potential problems, for example, poor quality cables, cables that are too long, or system internals with insufficient electrical shielding with high electrical interference on the bus. Errors that may cause a device transceiver error are:
o Bad PID
o CRC error
o Bit stuff error
o Extra bits in a packet
o Full Speed EOP ending on K
o Loss of high-speed valid before EOP (truncated packet)
o Overflow (host clock running too fast or device clock running too slow)
o Token larger than 3 bytes (this may occur when using the USB 2.0 Loopback plug behind a hub, with Low/Full speed devices connected to the hub).
It should be noted that device transceiver errors are not an indication that the USB port does not comply with the USB Specification."