---
title: "W5100 disconnect"
url: "https://maker.wiznet.io/forum/13960"
markdown_url: "https://maker.wiznet.io/forum/13960/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "geo0rpo"
created: "2020-07-27T05:34:42+09:00"
last_activity: "2020-07-27T06:45:01+09:00"
language: "en"
views: 683
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5100 disconnect

## Question

Asked by geo0rpo on 2020-07-27 in Ethernet Chips.

Hello,
The W5100 does not “sense” when I remove the ethernet cable. The socket remains open.
Is there a way to know if the cable is removed?
I also sometimes operate the W5100 through vpn where the connection may be lost but the cable is still connected. Is there a way to know if the connection is lost?

Thanks!!!

## Replies

### Reply 1 by becky, 2020-07-27

geo0rpo:

> The W5100 does not “sense” when I remove the ethernet cable. The socket remains open.
> Is there a way to know if the cable is removed?

The only way to know if the cable is removed is to transfer the data.
When the cable is removed and data is transmitted, the connection is disconnected by timeout because the Ack is not received.
Some chips of WIZnet such as W5500 and W5100S have a keep alive function that automatically sends packets periodically, but in the case of W5100, there is no such function.

geo0rpo:

> I also sometimes operate the W5100 through vpn where the connection may be lost but the cable is still connected. Is there a way to know if the connection is lost?

When the connection is lost, the value of the Sn_SR register changes. Please check this.

---

Source: https://maker.wiznet.io/forum/13960