Gilbarco Dispenser Twowire Protocol For Third Party Pump Controllers New exclusive May 2026

The Ultimate Guide to the Gilbarco Two-Wire Protocol for Third-Party Integration

If you’re developing a third-party pump controller or an automation system for a forecourt, you’ll eventually run into the Gilbarco Two-Wire Protocol. While it is a proprietary standard, it remains the backbone of communication for thousands of dispensers worldwide. 1. Hardware Fundamentals: The 45mA Current Loop

The most critical thing to understand about the Gilbarco Two-Wire protocol is that it is not RS-232 or RS-485 at the physical layer. It is a 45mA current loop.

Current Regulation: Gilbarco dispensers and CRIND devices typically operate on a 45mA loop, while some non-Gilbarco units may use 30mA.

Master-Slave Architecture: The controller (e.g., your third-party system) acts as the "Master" and initiates all communication. Dispensers are "Terminals" (slaves) and only respond when addressed.

Multi-drop Capability: A single communication loop can support up to 16 fueling positions.

Wiring Requirements: It requires 14 AWG twisted-pair stranded wire. Shielded wire is generally not recommended for these dispenser loops. 2. Communication Protocol Specifications

To talk to these pumps, your software needs to match these specific data parameters: Baud Rate: Typically 5787 bps or 4800 bps. Data Bits: 8 bits. Parity: Even. Stop Bit: 1. Data Format: Uses an 11-bit data format. 3. Essential Tools for Third-Party Controllers

Because most modern computers use USB or RS-232, you cannot connect directly to the pump's two-wire lines. You need a converter or interface board.

Communication Interfaces: Professional-grade interfaces like the Levtech LSP-FCG The Ultimate Guide to the Gilbarco Two-Wire Protocol

convert USB/RS-232 signals to the 45mA current loop required by the pump. Distribution Boxes (D-Box): Gilbarco uses a Distribution Box (PA0242)

to fan out the communication from the controller to individual dispensers. Simulators: For development without a physical pump, the Gilbarco RS-232 to Two-Wire Converter Box Kit

can be used in "Pump Simulator" mode to test your software logic. 4. Implementation Best Practices RS-232 to Two-Wire Converter Box Kit

The Gilbarco Two-Wire protocol is a proprietary serial communication standard used to connect fuel dispensers to point-of-sale (POS) systems and fuel site controllers

. For third-party controller developers, mastering this protocol requires understanding its physical current loop interface and its multi-drop messaging structure. www.mchip.net Physical Layer: 2-Wire Current Loop

Unlike standard RS-232 or RS-485, the Gilbarco protocol traditionally operates on a 2-wire current loop Levtech Service & Production

Requires unshielded twisted pair (UTP) cable with 10–12 twists per foot. Isolation:

To prevent equipment damage, third-party interfaces must use optical isolation between the dispenser data lines and the controller. Active vs. Passive:

The site controller typically acts as the "active" unit, providing the current for the loop. Communication Parameters 8 Data bits

Third-party controllers must match these specific serial settings to establish a handshake with Gilbarco dispensers: 4-20mA Comunications - All About Circuits Forum

3.2 Protocol Emulation

The controller software must be programmed to interpret the specific timing and voltage levels associated with the Gilbarco Two-Wire standard.

Flow Validation: The controller must differentiate between valid pulses (fuel flow) and switch noise.
Safety Logic: If the two-wire loop is broken (wire cut or disconnect), the system must default to a "Disabled/Safe" state, preventing unauthorized fueling.

3. Pump-Initiated Polling (Slave Mode for Controller)

Dispensers broadcast status changes (handle up, handle down, sale in progress, quantity delivered).
Controller listens as a passive master—no need for continuous controller-driven polling.

6. Common Issues in New Integrations

When implementing the Two-Wire protocol on a new third-party controller, watch for:

4.1 The Polling Cycle

The Master continuously cycles through connected pumps. A typical logic flow is:

Master sends command: "Request Status for Pump 01."
Pump responds: "Pump 01 Idle, Hook Down."
Master moves to Pump 02.

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.

9. References & Resources

Gilbarco Service Manual: Dispenser Communication Interface.
Weights and Measures Regulatory Guide (NIST Handbook 44 - US).
API Standard for Forecourt Device Integration.

Disclaimer: This report is for educational and engineering planning purposes. Developers must obtain official technical documentation and interface specifications directly from Gilbarco/Vontier to ensure compatibility with specific hardware revisions.

For implementing or troubleshooting a third-party pump controller using the Gilbarco Two-Wire (Current Loop) Protocol, you will need to reference specific technical manuals that detail the hardware electrical specifications and the logical command set. 1. Primary Protocol Documentation

The core of the Gilbarco Two-Wire system is a proprietary 30mA current loop protocol. For third-party development, the following documents are standard references: then to dispenser 2

Two-Wire Protocol Specification (TWO-IS-S1.0-5): This is the foundational logical interface manual. It defines the message format, including the 11-bit data frame and multi-drop addressing for up to 16 fueling positions.

Two-Wire Driver Hardware Specification (TWO-HW-S1.0-S): Essential for understanding the line-level electrical requirements, such as voltage levels and current loop tolerances. 2. Physical Connection & Interface Converters

Since most modern third-party controllers use RS-232 or RS-485, you often need an interface converter.

Technotrade PTS Controller: This is a popular third-party universal controller. The PTS Controller Technical Guide details how to bridge third-party systems to Gilbarco dispensers.

Levtech 2-Wire Interface: For PC-based control, the Levtech Communication Interface provides a USB-to-Two-Wire converter and includes testing software for Windows.

Allied Electronics Controllers: The Allied Installation Guide for Gilbarco provides specific wiring pinouts for connecting third-party Aegis or NeXGen controllers to Gilbarco "D-Boxes". 3. Key Communication Parameters

When configuring your third-party controller, the standard baud rates and frame settings depend on the dispenser series:

Highline-111 / Encore / Eclipse: 5787 bit/sec (Corporate baud rate), 8 Data bits, Even Parity, 1 Stop bit.

Highline-2 / Euroline: 4800 bit/sec, 8 Data bits, Even Parity, 1 Stop bit. 4. Hardware Setup (The D-Box) Zao NPF - Twotp-Is-Is2.26-P PDF - Scribd

5. Integration Strategy for New Controllers

When developing a new Pump Controller, the following workflow is recommended:

2. Key Specifications

Gilbarco Dispenser Twowire Protocol For Third Party Pump Controllers New __exclusive__ May 2026