For fuel retailers, integrating third-party systems with forecourt equipment can often feel like navigating a maze of proprietary barriers. However, the stands as one of the most enduring solutions for enabling third-party control over fuel dispensers. Officially named the "Gilbarco Dispenser Two-Wire Protocol for Third-Party Pump Controllers," this technology has served as a bridge between open innovation and proven hardware for decades, and it continues to evolve to meet the demands of modern fueling stations.
The Gilbarco Two-Wire protocol is a proprietary serial communication standard designed for data exchange between Gilbarco dispensers and control systems (like POS or forecourt controllers) using a single pair of wires
Because the protocol is proprietary and uses a non-standard 11-bit data format, direct connection (e.g., via Arduino or standard RS-232) often results in data being ignored by the pump. Third-party controllers often use dedicated converters: Levtech 2-Wire Interface
Third-party controllers must match these specific serial settings to establish a handshake with Gilbarco dispensers: 4-20mA Comunications - All About Circuits Forum The Gilbarco Two-Wire protocol is a proprietary serial
: Used by Highline-2, Euroline, Euro Dimension, Doms DP-9000, and Australian models. Data Format : 8 Data bits, Even Parity, and 1 Stop bit. Physical Layer
The customer lifted the handle; awaiting authorization.
Furthermore, Gilbarco continues to expand its dispenser lineup, including models like the , known for its reliability and advanced features. While these modern dispensers may offer newer communication options (such as IFSF over TCP/IP), the Two-Wire Protocol remains a supported and actively used interface for third-party control, ensuring that legacy investments are not stranded while enabling future upgrades. Physical Layer The customer lifted the handle; awaiting
The Master continuously cycles through connected pumps. A typical logic flow is:
+---------------------------------------------+ | Third-Party Pump Controller (Master) | +---------------------------------------------+ | (+) Current Loop Source | (-) Return v ^ =========#=============================#========= (2-Wire Trunk Line) | | +------#------+ +------#------+ | Dispenser 1 | | Dispenser 2 | +-------------+ +-------------+ Electrical Characteristics
The baud rate is model-dependent, which is a common stumbling block for new implementations: and earlier Highline models).
| Challenge | Description | Recommended Solution | | :--- | :--- | :--- | | | In multi-drop wiring, two pumps replying simultaneously can corrupt data. | Implement strict timing delays in the polling loop; verify Checksums on every received packet. | | Firmware Variations | Older pumps (V/R, Highline) vs. new pumps (Encore) may have slight firmware variances. | Design the software to auto-detect firmware versions or maintain a "Configuration Table" for specific pump models. | | Half-Duplex Limitations | The Two-Wire system cannot transmit and receive simultaneously. | Enforce a strict "Turnaround Delay" (e.g., 5ms) after sending a command before switching the UART to listen mode. | | Ground Loops | Electrical noise from pump motors interfering with data signals. | Hardware solution: Use Isolated Current Loop Converters. |
Building a controller entirely against raw documentation is high-risk. Successful development teams utilize a tiered testing approach:
The Gilbarco two-wire protocol is a (0–50 mA typical) used on Gilbarco dispensers (e.g., Encore 500, 700, Eclipse, and earlier Highline models). It allows a remote controller to:
Several cloud-based controllers (e.g., PDI’s FueLink, Kalibrate Edge) now offer two-wire via an IoT gateway that uses an on-board current-loop interface.
[State: Idle] -> Poll Pump -> If Nozzle Lifted -> [State: Calling] [State: Calling] -> Send Prices/Presets -> Send Authorize -> [State: Fueling] [State: Fueling] -> Poll Totals Real-Time -> If Nozzle Returned -> [State: Ended] [State: Ended] -> Read Final Transaction Data -> Send Clear/Acknowledge -> [State: Idle] 6. Challenges and Compliance