SIS Documentation
SIS3153
VME interface
Page 35 of 38
11.2 USB3.0 cable length
The recommended practical length limit for USB 3.0 cables is three meters.
In reality the maximum cable length for reliable USB3.0 operation may be limited by the hardware of the host
computer. USB3.0 ports on the front of tower enclosures are typically connected to the mainboard by cables,
while rear USB3.0 ports are attached to the mainboard directly, with the latter resulting in better performance.
By default the SIS3153 ships with 1.8 m cable length. The default cable length results in reliable longterm
USB3.0 operation with a MACBook Pro and a Celsius W530 workstation (USB3.0 front port) in our lab.
So far we have not found reliable cables with active redrivers that allow for a safe extension of the possible cable
length.
While PHY errors are expected at a certain rate due the given bit error rate, the Windows USB driver may
terminate upon the first PHY error occurrence.
Note 1:
In case you would like to cover longer distances you can use USB2.0 cables as a fallback solution
Note 2:
The flashing frequency of the front panel L LED signals the type of the USB link connection (1 Hz
USB, 2 Hz USB2.0 and 3 Hz for USB3.0)
Note 3:
The sis3153usb_internal_access_test program can be used to exercise the USB connection. A non
excessive PHY error count is ok., while link errors are critical. A screenshot of the output at program start is
shown below. The scrrenshot on the next page shows the output after the DMA read/write loop sequence has
started.
