---
title: "General structure of all commands"
slug: "general-structure-of-all-commands"
updated: 2024-07-04T11:07:35Z
published: 2024-07-04T11:07:35Z
canonical: "docs-linescan.alliedvision.com/general-structure-of-all-commands"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs-linescan.alliedvision.com/llms.txt
> Use this file to discover all available pages before exploring further.

# General structure of all commands

The XLC4 commands are transferred in a command message of a uniform string structure:

| Start | Address | Space | Command | End |
| --- | --- | --- | --- | --- |
| STX | “#”, HexChar | Blank | String | ETX |
| 0x02 | 0x23, HexChar | 0x20 |  | 0x03 |
| Start of command | Optional, for use with RS485 port |  |  | End of command |
|  | Allowed characters: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, F |  |  |  |

The message string is enclosed by STX as start character and ETX as end character. If the controller does not receive STX, the message will be ignored. If the controller does not receive ETX, no response will be sent. Handle this issue using a time-out.

The command string has the following structure:

| CommandID | Space | ParameterList |
| --- | --- | --- |
| 2 or 3 uppercase characters | 0x20 | - List of decimal or hexadecimal numbers - Alphanumeric characters |
| See at each command | As separator from PrarmeterList | More than one parameters are separated by a blank character (Space) or by comma (“,”) comma is used to separate numbers |

Each command message sent to the XLC4 is acknowledged by a response message of the following structure:

ResponseMessage = STX , Response , ETX

| Response | = | ResponseID , [ValueList] |
| --- | --- | --- |
| ValueList | = | Space, Value, {“,” , Value} |
| Value | = | decimal number \| hexadecimal number \| single character \| string |