https://socialtechnet.com/story5066576/boost-your-workflow-with-the-iogear-2-port-usb-2-0-automatic-printer-switch
boostworkflowiogearportusb
https://www.dlink.com/hu/hu/support/faq/adapters/print-servers/dp-series/on-the-dp-300-serial-port-which-pins-are-used-to-communicate-with-my-printer
serial portdppinsused