Gilbarco Dispenser Twowire Protocol For Third Party Pump Controllers New Jun 2026

| Pitfall | Consequence | |---------|--------------| | Using RS-232 levels directly | Destroy dispenser’s optocoupler | | Ignoring parity bit | Random transaction failures | | Polling faster than 200 ms | Dispenser lockup (floods buffer) | | No timeout handling | System hangs if dispenser offline | | Assuming same polarity on all models | Some older Gilbarco models swap loop + and - |

| 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 |

At its core, the Gilbarco Two-Wire Protocol is a that allows an external computer system—commonly known as a "third-party pump controller"—to manage and control a Gilbarco fuel dispenser. The "Two-Wire" designation refers to the physical wiring method, which uses a simple, two-conductor cable for communication. This is a distinct departure from multi-wire systems that may require dedicated cabling for each fueling point. A traditional pump control solution, such as a Pump Control Module (PCM), may require six wires per fueling position. In contrast, the Two-Wire Protocol dramatically simplifies site wiring by allowing multiple dispensers to be connected on a single loop. | Pitfall | Consequence | |---------|--------------| | Using

The Gilbarco Two-Wire communication protocol is a . The forecourt controller or Point of Sale (POS) system acts as the master device. The individual fueling positions operate strictly as slave units. Network Capacity & Topology

The nozzle is returned. Transaction data is locked in dispenser memory awaiting clearance. B. Control Commands A traditional pump control solution, such as a

Each character transmitted over the loop follows a standard UART configuration: 1 bit Data Bits: 8 bits Parity: Even parity Stop Bits: 1 bit

The master controller must provide the loop power supply (typically 12V to 24V DC regulated through a constant current circuit) to drive the 45mA loops. Software State Machine Implementation The forecourt controller or Point of Sale (POS)

: Often referred to as "Corporate baudrate," used for Highline-111 and newer international models. Data Framing : 8 Data bits, Even Parity, and 1 Stop bit.

The protocol utilizes a current loop interface, typically operating as a multi-drop serial communication link. It uses an 11-bit data format.