---
title: "WIZ550Web CR+LF behaviour"
url: "https://maker.wiznet.io/forum/15757"
markdown_url: "https://maker.wiznet.io/forum/15757/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "MiroKek"
created: "2025-06-11T18:44:21+09:00"
last_activity: "2025-06-12T17:44:05+09:00"
language: "en"
views: 5
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# WIZ550Web CR+LF behaviour

## Question

Asked by MiroKek on 2025-06-11 in Ethernet Chips.

1. If the received data contains CR+LF (and we need it there), the page is reset (it reloads the initial page). (while the system accepts all other characters, only CR and LF really cause the reset)

2. We need CR+LF to be performed in the window where the data is displayed as it should be – that is, line feed to be performed. So if something like:
data1 CR+LF data2 CR+LF data3 CR+LF comes in, so that it is displayed in the window like this:

data1
data2
data3

## Replies

### Reply 1 by TheoIm, 2025-06-12

Hello,

This issue is related to the way AT commands are handled internally by the firmware of the WIZ550WEB.

WIZ550WEB is designed to terminate all command inputs with CR+LF. This is because the command parser in the firmware recognizes \r\n as the end of a command or a signal to execute it.

In other words, if the incoming serial data contains \r\n, the system may misinterpret it as part of an AT command rather than general data, or unintentionally trigger the command processing routine.
As a result, this can cause behaviors like a page reload (reset).

For more details, please refer to the following link:
<https://docs.wiznet.io/Product/App-Module/WIZ550web/users-guide-eng>

Thank you

---

Source: https://maker.wiznet.io/forum/15757