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Start

This document aims to give a detailed overview of how to communicate with the RAVAS RedBox scale using the RedBox protocol. The protocol uses protocol buffers to encode its messages.

Glossary
  • Scale: The weighing scale. A Ravas Redbox can contain multiple weighing scales. Usually only one scale is used (Index 0)
  • Loadcell: A straingauge to measure the applied weight and converts this into a electrical signal
  • Tare: Subtracting e.g. the weight of a pallet
  • Gross weight: Total weight on the scale
  • Net weight: Weight with tare subtracted.

Getting started

Protocol buffer decoding/encoding libraries exist for all popular languages. See: protobuf-compiler-installation.

Schema file (.proto)

See redbox-protobuf

Packet structure

Each packet starts with a 3 byte header. This header contains a fixed preamble byte (0x3A) and the length of the protobuf message (u16). 

packet-beta
title Packet header
0-7: "Preamble (0x3A)"
8-23: "Length"
The header is followed by Length bytes, which is the encoded protobuf message. Multiple packets can be sent one after the other. This packets will be handled sequentially.

Transport layer: TCP/IP

The protocol is available over multiple physical transport layers. For now the scope of this document is limited to the TCP/IP layer. The RedBox is listening on TCP port 49112 for a connection. Once connected, you can start sending Requests.

To discover a RedBox on the network, send an empty UDP broadcast packet to port 49111. The RedBox responds with its own empty UDP packet.

Usage

Initially the communication can follow a basic Request - Response flow.

sequenceDiagram
    Client->>RedBox: Request
    RedBox-->>Client: Response

Example

See Basic example (C#) for a minimal example.