What is Gilbarco Two Wire Protocol and how does it work?
Gilbarco Two Wire Protocol is a wireless digital protocol for data communication between fuel dispensers and point-of-sale (POS) systems. It is used for Gilbarco Encore 500 and SK700 dispensers, as well as other products such as kiosks, vending machines, and gas dispensers[^2^] [^4^].
The protocol uses two wires to transmit and receive data in a serial format. The data consists of commands, responses, and status messages that control the dispenser functions and report the transaction information. The protocol can be implemented on the POS side using a communication interface that connects to the dispenser via an optical isolator[^2^]. The interface can handle one single side or one double side pump[^2^] [^3^].
It is simple and reliable, requiring only two wires for communication.
It is compatible with various Gilbarco products and supports different features such as prepay, postpay, card reader, etc.
It can be used with wireless modems or TCP/IP networks for remote access and monitoring.
The protocol also has some limitations, such as:
It has a limited data rate of 9600 bps.
It requires a specific hardware interface to connect to the dispenser.
It is proprietary and not publicly documented.
Gilbarco Two Wire Protocol is one of the standard protocols for fuel dispenser communication. It is widely used in the fuel retail industry and provides a secure and efficient way of data exchange between the dispenser and the POS system.
In this article, we will explain how the Gilbarco Two Wire Protocol works and what are the main components and features of the protocol. We will also provide some examples of how to use the protocol with different Gilbarco products and devices.
How does the Gilbarco Two Wire Protocol work?
The Gilbarco Two Wire Protocol is based on a master-slave architecture, where the POS system acts as the master and the dispenser acts as the slave. The master initiates the communication by sending a command to the slave, and the slave responds with a response or a status message. The communication is bidirectional, meaning that both the master and the slave can transmit and receive data on the same two wires.
The protocol uses a serial format with 8 data bits, 1 start bit, 1 stop bit, and no parity bit. The data rate is 9600 bps. The protocol uses a special character called DLE (Data Link Escape) to mark the beginning and end of a message. A message consists of a header, a body, and a checksum. The header contains the address of the sender and receiver, the message type, and the message length. The body contains the data or parameters of the command or response. The checksum is a byte that verifies the integrity of the message.
The protocol defines several types of messages, such as:
Command messages: These are messages sent by the master to request an action from the slave, such as start or stop a transaction, authorize or reject a payment, read or write data, etc.
Response messages: These are messages sent by the slave to acknowledge or reject a command from the master, or to provide data or status information requested by the master.
Status messages: These are messages sent by the slave to report an event or condition that occurred on the dispenser, such as nozzle lift, error code, transaction complete, etc.
The protocol also defines several commands and responses for different functions and features of the dispenser, such as:
Pump control: These are commands and responses that control the pump operation, such as start or stop delivery, preset volume or amount, lock or unlock nozzle, etc.
Payment control: These are commands and responses that control the payment method and authorization, such as card reader enable or disable, card data read or write, PIN entry request or response, etc.
Data control: These are commands and responses that read or write data from or to the dispenser memory, such as product price, totalizer value, configuration parameter, etc.
Display control: These are commands and responses that control the display content and format on the dispenser screen, such as display text or graphic, clear display, set font size or color, etc.
What are the main components and features of the Gilbarco Two Wire Protocol?
The Gilbarco Two Wire Protocol requires some hardware and software components to enable the communication between the dispenser and the POS system. The main components are:
The dispenser: This is the device that delivers fuel to the customer's vehicle. It has a pump unit that controls the flow rate and volume of fuel, a meter unit that measures 29c81ba772