Unlike modern Ethernet (TCP/IP) which requires complex switching and addressing, the two-wire protocol uses a current loop. A master controller (traditionally a Gilbarco POS) sends commands by modulating current on the loop. Dispensers listen for their unique address and respond on the same two wires.
For decades, the fuel retail industry has operated in a state of semi-walled gardens. Major dispenser manufacturers, particularly Gilbarco Veeder-Root, developed proprietary communication protocols that made it notoriously difficult for third-party point-of-sale (POS) systems, fleet fueling managers, and automated tank gauge (ATG) integrators to communicate directly with the dispenser’s hydraulic components. particularly Gilbarco Veeder-Root