User Manual and Operating Guide

2. The Barco Projection Protocol
2. THE BARCO PROJECTION PROTOCOL
Overview
• T h e Barco P ro ject io n Pro t oco l expla in ed
• Ethernet communication
• RS232/RS422/USB -B communication
• The command representation in this manu al
2.1 The Barco Projection Protocol explained
Usage
The Barco Projection Protocol is used for the serial communication with a B arco device. T his can be done by the following ways:
• Ethernet
• RS 232
• RS 422
•USB-B
Structure
Each command is built up from a start byte, device address, request/response, checksum and stop byte (image 2-1).
Start byte Device address
Request /
Response
Checksum Stop byte
1 byte (0xFE) 1 byte
1..n bytes
1 byte 1 byte (0xFF)
Image 2-1
Command structure
• St art byte: used to let the receiver k now that a comman d will follow.
• Device address: when multiple devices (m aximum 25 6) are connected on t he same physical conn ection, the device address
is used to specify the device (only for RS232 connections). In case of an Ethernet conne ction, this s hould be set to 0.
• Req uest/Response: the actual command bytes.
• Ch ecksum: used to detect if any errors occurred d uring transmission or reception of the command.
• Stop byte: used to let the receiver know that the end of a command has been reache d.
How is the checksum calculated?
The checksum calculation is base d on mod ular arithmetic:
Checksum =(Device address + Request/Response) modulo 0x100 (or 256)
Bytes conversion
Some bytes cannot be used in a comman d. If they do appear in the request/response or checksum, they must be converted. The
table below g ives an overview.
Byte
After conv ersion
0x80 0x80 0x00
0xFE 0x80 0x7E
0xFF 0x80 0x7F
When a byte sequence from the after conversion co
lumn is received, that sequence must be converted to the
corresponding byte.
Characters and character strings
Each character is sent as a byte, us ing the ANSI encoding method.
R5905746 COMMAND CATALOG 06/01/2014
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