For example, connect two AV4PRO switches together, where the USB from the Master of port 1 is connected to the console port of the Slave. The keyboard and mouse are connected to the master AV4PRO.
Hold down the CTRL+ALT key (default) and press 1 to chose port one of master, press 2 then release the CTRL+ALT keys. This will instruct the AV4PRO to switch to port 1 on the master and then to port 2 on the slave.