I've disconnected the MDB cable from the first MDB port (MDB1) and connected it to MDB2 on the vending machine. I contacted our vending machine supplier Benleigh Vending and they stated that the switching of connections should be automatic but I can't seem to get a reply from MDB2 when I send a signal from my PC application which is sent from an application using RS232 (USB Virtual COM Port COM7) port to the MDB port on the vending machine. I chose the MDB2 port on the vending machine as MDB1 caused issues with the vending machine operations and the PC running Windows 10 Professional. I searched for a switch on the motherboard but couldn't find one. I'm wondering what I should do?