While the "new" protocol access is exciting, it is not plug-and-play.
| Parameter | Specification | | :--- | :--- | | Physical Layer | 20mA Current Loop (not RS-232 voltage levels) | | Topology | Daisy-chain (one pair of wires from controller to dispenser 1, then to dispenser 2, etc.) | | Wire Type | Twisted pair, shielded (Belden 8760 or equivalent) | | Max Distance | 2000 ft (600m) per loop | | Communication | Half-duplex, asynchronous | | Baud Rate | 1200 bps (fixed, non-configurable on most legacy dispensers) | | Data Format | 1 start bit, 7 data bits, even parity, 1 stop bit |
The Gilbarco Two-Wire Protocol (often referred to as "Type A" or "Current Loop") is a legacy serial communication standard used to control fuel dispensers. For third-party pump controllers (non-Gilbarco POS), this protocol allows basic fuel authorization, grade selection, and transaction monitoring without requiring a full Gilbarco G-SITE or Passport controller.
This document outlines the specifications for new third-party controller integrations.
For decades, the fuel retail industry has operated in a state of semi-walled gardens. Major dispenser manufacturers, particularly Gilbarco Veeder-Root, developed proprietary communication protocols that made it notoriously difficult for third-party point-of-sale (POS) systems, fleet fueling managers, and automated tank gauge (ATG) integrators to communicate directly with the dispenser’s hydraulic components.
Enter the renewed focus on the Gilbarco dispenser two-wire protocol. While the physical two-wire loop has existed for years (handling pulser data and sale authorization), a new wave of innovation has arrived. Recent advancements in protocol translation hardware and software are finally cracking the code, allowing third-party pump controllers to leverage this robust, low-latency communication method like never before.
This article dives deep into what the Gilbarcotwo-wire protocol is, why it is experiencing a renaissance for third-party integrators, and how your business can benefit from this new level of control.
| Challenge | Description | Recommended Solution | | :--- | :--- | :--- | | Collision Detection | 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. |
While the "new" protocol access is exciting, it is not plug-and-play.
| Parameter | Specification | | :--- | :--- | | Physical Layer | 20mA Current Loop (not RS-232 voltage levels) | | Topology | Daisy-chain (one pair of wires from controller to dispenser 1, then to dispenser 2, etc.) | | Wire Type | Twisted pair, shielded (Belden 8760 or equivalent) | | Max Distance | 2000 ft (600m) per loop | | Communication | Half-duplex, asynchronous | | Baud Rate | 1200 bps (fixed, non-configurable on most legacy dispensers) | | Data Format | 1 start bit, 7 data bits, even parity, 1 stop bit |
The Gilbarco Two-Wire Protocol (often referred to as "Type A" or "Current Loop") is a legacy serial communication standard used to control fuel dispensers. For third-party pump controllers (non-Gilbarco POS), this protocol allows basic fuel authorization, grade selection, and transaction monitoring without requiring a full Gilbarco G-SITE or Passport controller. While the "new" protocol access is exciting, it
This document outlines the specifications for new third-party controller integrations.
For decades, the fuel retail industry has operated in a state of semi-walled gardens. Major dispenser manufacturers, particularly Gilbarco Veeder-Root, developed proprietary communication protocols that made it notoriously difficult for third-party point-of-sale (POS) systems, fleet fueling managers, and automated tank gauge (ATG) integrators to communicate directly with the dispenser’s hydraulic components. | Challenge | Description | Recommended Solution |
Enter the renewed focus on the Gilbarco dispenser two-wire protocol. While the physical two-wire loop has existed for years (handling pulser data and sale authorization), a new wave of innovation has arrived. Recent advancements in protocol translation hardware and software are finally cracking the code, allowing third-party pump controllers to leverage this robust, low-latency communication method like never before.
This article dives deep into what the Gilbarcotwo-wire protocol is, why it is experiencing a renaissance for third-party integrators, and how your business can benefit from this new level of control. then to dispenser 2
| Challenge | Description | Recommended Solution | | :--- | :--- | :--- | | Collision Detection | 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. |