The Gilbarco Two-Wire protocol is a proprietary, multi-drop current loop communication standard used to link fuel dispensers with point-of-sale (POS) systems or third-party pump controllers. It operates as a master-slave system where the controller (master) initiates all communication, and individual dispensers (slaves) respond only when addressed. 1. Technical Specifications
The protocol relies on a 45mA current loop for signal transmission. Modern implementations often require unshielded twisted pair (UTP) wiring to avoid interference.
Data Format: 11-bit data format (1 start bit, 8 data bits, 1 even parity bit, 1 stop bit). Baud Rates: 4800 bps: Standard for Highline-2 and Euroline models.
5787 bps: "Corporate baudrate" used for Highline-III, Encore, and Eclipse series.
Loop Capacity: Supports up to 16 fueling positions on a single communication loop.
Voltage: Typically driven by a 12VDC unregulated supply at the distribution box. 2. Interfacing Third-Party Controllers RS-232 to Two-Wire Converter Box Kit The Gilbarco Two-Wire protocol is a proprietary, multi-drop
The Gilbarco Two-Wire protocol is a proprietary serial communication standard based on a 45mA current loop
. It is primarily designed to facilitate data exchange between fuel dispensers and control systems (like POS terminals or forecourt controllers) over a single pair of wires. Physical Layer Specifications
The protocol uses a multi-drop configuration supporting up to 16 fueling positions (pumps) per communications channel. Baud Rates
: Depending on the dispenser model, the protocol typically uses: 5787 bit/sec
: Known as the "corporate baud rate," used for models like Highline-111, Euroline, and Euro Dimension. 4800 bit/sec : Used for older models like Highline-2 and Euroline. Data Format : 8 data bits, Even parity , and 1 stop bit. Logical Interface Dispensers broadcast status changes (handle up
: It is a master-slave protocol where only the master (the console or controller) is permitted to initiate communication. Third-Party Integration Solutions
Since the protocol is proprietary, third-party pump controllers often require specialized hardware interfaces to convert the current loop signal into standard serial (RS-232/RS-485) or USB formats. 4-20mA Comunications - All About Circuits Forum
Two-wire protocol traditionally only controls one product per hose. For blender units (Encore 700), you need extended commands.
If you are an integrator or site owner looking to implement this new communication pathway, here is the technical roadmap.
| Manufacturer | Product | Notes | |--------------|---------|-------| | FMS (Fuel Management Systems) | FMS 3000 | Fleet keypad, two-wire native | | Syntech Systems | FMS-PRO | Supports two-wire + RS-485 | | Raytec | RC-200 | Retrofit for car washes | | Wayne (Dover) | iX Pay | Limited two-wire legacy mode | | Verifone | Commander (with serial adapter) | Via Gilbarco’s “G-SITE” adapter | sale in progress
New (2025): 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.
The most common failure point for third-party developers is the Authorize/Deauthorize handshake.
Subject: Integration Standards for Gilbarco Dispensers via Two-Wire Protocol Target Audience: Forecourt System Integrators, POS Developers, Petroleum Equipment Technicians
The Master continuously cycles through connected pumps. A typical logic flow is:
Note: If a pump does not respond within a specific timeout window (usually 50ms–200ms), the Master marks it as "Offline" and proceeds to the next pump.
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.