The Gilbarco Two-Wire protocol is a proprietary serial communication standard based on a 45mA current loop
Whether you are a fleet operator wanting to bypass expensive POS licensing, a C-store owner integrating loyalty rewards directly into the nozzle, or a hobbyist reviving a classic dispenser, the two-wire protocol is your golden ticket.
The serves as the primary communication link between millions of fuel dispensers and Point of Sale ( POS ) forecourt controllers worldwide . Originally developed as a proprietary data standard by Gilbarco Veeder-Root , this protocol has become an essential integration requirement for third-party automation systems. Independent developers of forecourt controllers, payment kiosks, and fleet management software must thoroughly understand both the physical and logical layers of this communication structure to achieve seamless hardware interoperability. The Physical Layer: Active Current Loop Electronics The Gilbarco Two-Wire protocol is a proprietary serial
Never initiates communication. It only responds when it detects its unique node address in a command frame sent by the master.
Nozzle returned to boot, final transaction data ready for retrieval. Nozzle returned to boot, final transaction data ready
The two-wire protocol returns pulses as a frequency. The new converters output these as standard quadrature encoder pulses or Modbus registers. Your third-party pump controller can now read with sub-penny accuracy.
5787 bit/sec (Corporate baud rate), 8 Data bits, Even Parity, 1 Stop bit. D. The Clear/Acknowledge Command
The Gilbarco dispenser two-wire protocol offers several benefits to fueling station operators, including:
Maximum dollar value or volume allowed for the transaction (crucial for prepay or fleet limits). C. The Data Readout Command (Collection)
Once a transaction terminates, the controller issues a data readout command to harvest the exact sale details. The dispenser responds with structured ASCII strings indicating: Total money dispensed. Total volume dispensed. Unit price per gallon/liter applied during the sale. The tier/grade index utilized. D. The Clear/Acknowledge Command