USB2Test Display |
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The main USB2Test Application window is divided into 4 sections: Select USB test, USB test data selection, Results & Control buttons. The above diagram shows the Results Display following BOTH a successful Loopback test and a Benchmark test.
Test selection This section allows for the test type, loopback test load, USB test device and test duration. Test Mode: The Loopback function or benchmark function should be selected by selecting either Loopback or Benchmark. Loopback: When a Loopback test is started, USB2Test will send a packet of data (64bytes in Full-speed and 512bytes in High-speed) to the USB device, which will loop this data back in firmware and send the same data back to the PC. This is defined as 1 Loopback operation. This will be repeated until the test is stopped manually or the test duration is reached. Benchmark: Allows the data transfer rates for short bursts of data transfer to be measured. When a Benchmark test is started, USB2Test will send a block of data (2kB in Full-speed and 32kB in High-speed) to the PassMark USB2 device, which will count the number of packets (64byte in Full-speed and 512-byte in High-speed) per USB microframe (1ms in Full-speed and 125us in High-speed) and calculate the maximum speed based on these metrics. This is defined as 1 Benchmark operation. This is performed 10 times, followed by the benchmark of receive speed, where the PC requests a block of data from the PassMark USB2 device. This will be repeated until the test is stopped manually or the test duration is reached. The USB2 firmware sends packets with pre-defined values to the PC. The maximum rate is then calculated in the same fashion. This test is performed 10 times. The overall maximum, average and minimum of the read and write results are then displayed. Note: The benchmark speed reduces with the more USB devices you connect to your PC. As you add USB devices to the (Universal Serial) Bus you will observe a reduction in maximum performance of each USB device. This is to be expected and is due to increasing overheads on the bus as more devices are added. The overheads introduced from each USB device on the bus reduces the number of bytes that can be utilized by other USB devices during a frame (i.e.. less data blocks can be transferred per frame ). Overheads include packet organization, framing information, polling, clock adjustment and reserved time. It is recommended that all other USB devices be disconnected from your PC when performing the benchmark test if you plan to obtain the maximum data rate. Note 2: The USB 2.0 loopback plug will connect to the USB port at the highest possible speed, either Fullspeed (12Mb/s) or Highspeed (480Mb/s). If you need to test a Highspeed USB 2.0 port at Fullspeed, you can disable the Enhanced USB Host Controller in device manager, which will have the effect of dropping all ports back to USB 1 Fullspeed. From Windows Device Manager, under Universal Serial Bus controllers, the USB2 enhanced Host Controller will look something like “Intel® 82801FB/FBM USB2 Universal Host Controller – 265C”. Only disable this device if you are certain that no other hardware is connected to the system. i.e. at your own risk. Loopback load: This option allows the data transfer load to be modified by inserting delays between each Write and Read cycle. It is only applicable to the loopback test. Device: This drop-down list shows each connected PassMark USB2 device (i.e. Each port being tested). Each port will have an indication of whether the port is configured as high or full-speed. The relevant device should be selected for each test. If PassMark USB2 devices are added or removed while the application is running, “Reset All” will update this drop-down selection list with the current devices. Similarly, if Host controllers are added or removed while the application is running, “Reset All” will update this drop-down list with the current device operational speed, Full- or High-speed. Duration: Sets the duration of tests. Specified in minutes. Specifying “0” means run the next test forever – i.e. until manually stopped.
USB test data selection Different test data can be sent to the USB 2.0 loopback plug (this provides different types of reliability testing and does alter the transfer speed). One of the following may be selected per test:
Verify data transferred: Specifies (i) that during a Loopback test the data sent to the PassMark USB2 device matches the data received (ii) the predefined Benchmark data expected from the PassMark USB2 device is correct.
Results The USB2Test results are contained in 3 sections: Title bar, test summary and a benchmark graph result. Results heading: Displays two lines:
Test summary: Displays a textual summary of the tests as they occur. This summary starts with a list of the PassMark USB devices connected to USB ports. Specifically, this includes the:
Loopback test results show the number of:
It should be noted that device transceiver errors are not an indication that the USB port does not comply with the USB Specification.
Benchmark results show the Maximum rate for reading and writing over the USB port (i.e. the Maximum reading and writing speed measured by the USB2.0 Loopback plug). The average and minimum transfer rates are also displayed. Note: The "Interrupted data transfer warning. Test plug limited max. data rate. Retrying." message is not an error, but is an indication that the previous test measurement sample may not have shown the maximum speed and has been ignored. This can occur for example due to the benchmark test sample period being interrupted by other USB traffic on the shared bus. The current test results (i.e. since the last “Reset All” may be viewed by sliding the scroll bar on the right hand side of the results section). Benchmark graph: Displays the overall maximum USB rate measured over the port that the current test device is connected. Below this value, a graph displays 2 column bars, the left-hand bar shows the maximum read rate and the right-hand bar shows the maximum write rate (in Mb/s). Both bars are color coded with the following meaning:
Control buttons The Control buttons are at the bottom of the main window. Start: Starts a test based on the settings described above. Stop: Stops a test. Save Log: Allows a “Test Summary” to be saved to a file. Up to the last 3000 logged lines are saved. Reset All: Resets the display and loads any updated USB information (e.g. Newly attached PassMark USB2 devices or changes in port operational rates). To verify that the LEDs are working on all USB 2.0 loopback plugs attached, “Reset All” will also switch all LEDs off for 0.5 seconds (except the central red power LED), and then switch all LEDS on for 0.5 seconds. The LEDs will then return to their initial state. About: Displays information about this software. Help: Provides on-line help. Exit: Closes this software. |