Thoughtpad T540p issues with video transfer from USB-C to USB-A through a hub to the monitor.
Thoughtpad T540p issues with video transfer from USB-C to USB-A through a hub to the monitor.
Hi All A bit of an edge case, I have a Thinkpad T540p with 4 USB slots and a display port. I also have a brand new elitebook which has USB c. I use both lapops interchangably via VGA to the same monitor but everytime i swap them round i have to transfer the kb/mouse & VGA wires. I have a USB C hub which came with the elitebook where i can hook up the USB prepherials and the VGA wire however the thinkpad has no USB c slots - only USB A & a display port. I purchased a USB c to USB A adapter cable so that everytime i swap laptops i only have to remove/add the adapter cable. When i try to this setup with the thinkpad however the monitor does not display the video output. The thinkpad recoignises the USB hub (as the Kb/Mouse connect) however no display. I know the monitor has also recoignised 'some' sort of signal as it shows a black screen as opposed to the 'no signal detected' when i pull the VGA cable out. In the settings only the laptop display shows. I have tried all 4 usb slots but to no avail. Im pretty sure USB A can stream video so im unsure as to why its not working? Is there a solution or alternatively will a USB c to display port adapter wire work? Thanks!
USB-C includes variations known as alt-modes, among which Displayport is one. Due to its four high-speed channels (USB 3.x typically uses two), it can redirect the remaining two for video transmission. USB-A lacks these additional pins, making it incompatible with alt-mode devices. Even standard USB ports don't internally support video routing, regardless of lane availability.
An adapter converting USB-C to display port could also function.
Only when the device is actively powered (such as a DisplayLink adapter) does this problem occur. A standard USB-C to DP cable won’t experience the same issue.