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.
Request to authorize grade 1 for $50.00: Dispenser response (success): <SOH> 0 1 0 0
<SOH> 0 1 1 5 0 0 0 EOT
Where:
Dispenser response (success):
<SOH> 0 1 0 0 <EOT> (Ready to lift nozzle) Dispenser response (success):
<
Integrating with the Gilbarco Two-Wire protocol offers a reliable method for third-party pump controllers to manage fuel dispensing. However, it requires strict adherence to the Master-Slave polling architecture and precise hardware interfacing (Current Loop conversion). Successful implementation relies on a robust software state machine capable of handling communication timeouts and adhering to local Weights and Measures regulations regarding transaction integrity. 0 1 0 0 <