Gilbarco Dispenser Twowire Protocol For Third Party Pump Controllers New Site

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

This is a specialized request regarding the Gilbarco Two-Wire Protocol (often referred to as the Current Loop or Type A protocol), specifically in the context of third-party pump controllers (e.g., for retrofitting fleet fueling, mobile pay apps, or site controllers like Verifone, Wayne, or NCR). Below is a proper technical review of this topic, focusing on what’s “new” or relevant for third-party integration in 2024–2026.

1. Protocol Overview (Legacy but Active) The Gilbarco two-wire protocol is a current-loop serial interface (0–50 mA typical) used on Gilbarco dispensers (e.g., Encore 500, 700, Eclipse, and earlier Highline models). It allows a remote controller to:

Authorize a specific fueling point (pump/ hose). Read real-time volume delivered. Read price and transaction status. The Gilbarco Two-Wire protocol is a proprietary, multi-drop

Critical note: This is not the same as Gilbarco’s newer “Ethernet/EDH” (Encryption Device Handling) or “Passport” protocol. It is unencrypted , polled , and half-duplex .

2. Why Third Parties Still Use It (New Context) Despite being 30+ years old, the two-wire protocol remains relevant because:

Retrofit cost: Replacing all dispensers at a site is expensive. Many independent fuel stations, fleet depots, and car wash + fuel combos still have Gilbarco two-wire dispensers. Simplicity: It requires only two wires (twisted pair, 18–22 AWG) per dispenser or loop. No dispenser modification needed – works through the existing dispenser’s “remote control” port (often an Amphenol connector or terminal strip). Technical Specifications The protocol relies on a 45mA

New driver: With the rise of cloud-based POS , automatic vehicle identification (AVI) , and EV charging integration , third-party controllers (e.g., Fuellogic, Raytec, Syntech, FMS) are actively seeking two-wire support as a backward-compatible option.

3. Technical Requirements for a Third-Party Controller To correctly implement the Gilbarco two-wire protocol, your controller must: A. Hardware

Current-loop driver (open-collector or opto-isolated, capable of sinking 0–50 mA). Typical logic: Baud Rates : 4800 bps : Standard for

Idle = 0 mA (or very low ~4 mA in some revisions) Mark (logic 0) = 0 mA Space (logic 1) = 20–30 mA

Receive comparator (detect current from dispenser’s response). Galvanic isolation – dispensers are often on different grounds; common-mode voltage can exceed ±12V. Overvoltage protection (±60V transient) – pump motors and relays induce spikes.