---
title: "WizFi310 open socket \"server mode\" (TSN) returns invalid parameter"
url: "https://maker.wiznet.io/forum/14576"
markdown_url: "https://maker.wiznet.io/forum/14576/md"
type: "Forum topic"
category: "Wireless"
author: "JMRib"
created: "2022-06-14T13:41:40+09:00"
last_activity: "2022-06-17T00:35:44+09:00"
language: "en"
views: 293
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# WizFi310 open socket "server mode" (TSN) returns invalid parameter

## Question

Asked by JMRib on 2022-06-14 in Wireless.

Hi

We are developing a new product with a WizFi310 device. I’m trying to open a “TCP SERVER normal” socket using:

`AT+SCON=O,TSN,,,2330`

and always returns:

`[ERROR: INVALID INPUT]`

What could be the problem?

Thank you

## Replies

### Reply 1 by JMRib, 2022-06-16

Resolved! The socket listener was already opened…

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Source: https://maker.wiznet.io/forum/14576