Connecting a standard PC or a modern PLC to a Gilbarco dispenser often requires an interface converter to bridge the gap between RS-232/USB/RS-485 and the 2-wire current loop.
⚠️ The third-party controller must have an active 20mA current loop interface . If your controller only provides RS-232, you must install an isolated 20mA converter (e.g., B&B Electronics 232LPTTL or equivalent).
If you are your own controller, start with a known current-loop chip like LTC1487 or MAX491 configured for loop mode, and capture bus traffic with a logic analyzer first (e.g., Saleae) before writing any code. Connecting a standard PC or a modern PLC
: Minimum 18 AWG for runs up to 1000 feet; 14 AWG for runs up to 2600 feet.
Third-party controller manufacturers utilize this protocol to: If you are your own controller, start with
For third-party integration, the protocol requires specific communication parameters and physical wiring:
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. connects to the first dispenser
The master (third-party pump controller) retains exclusive rights to initiate communications on the multi-drop loop. All packets utilize a lean payload architecture designed to optimize loop throughput:
The protocol is typically divided into variants based on the specific dispenser model and baud rate requirements: :
The physical wiring must be carefully planned. Dispensers are typically connected in a topology, where the loop starts at the controller, connects to the first dispenser, continues to the next, and so on, before returning to the controller to complete the circuit. However, it is crucial to note that the maximum load capacity for a single channel is typically four fuel dispensers . If more dispensers are present or if a break in the loop causes an entire chain to fail, installers often opt for multi-channel interface converters . These devices allow dispensers to be distributed across separate, independent channels, ensuring that a failure on one pump does not take down the entire forecourt.
To connect a Gilbarco dispenser to a new third-party controller, specific hardware and software integration must take place. 1. The Interface Unit / Converter
