---
title: "Unable to send UDP data"
url: "https://maker.wiznet.io/forum/11389"
markdown_url: "https://maker.wiznet.io/forum/11389/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "chiasyan"
created: "2015-10-19T11:39:44+09:00"
last_activity: "2017-05-04T08:37:12+09:00"
language: "en"
views: 506
replies: 0
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# Unable to send UDP data

## Question

Asked by chiasyan on 2015-10-19 in Ethernet Chips.

Hi,

I was trying to run the loopback_udps() but the code failed while it tries to run the sendto() function, which always return “SOCKERR_TIMEOUT”.

In another word, the send operation has failed. (which is at the very last few lines of the sendto())

I am able to receive data via recvfrom().

Also, I am able to run the loopback_tcps() without any problems, so I am pretty sure that my network config should be alright.

I have added exceptions in my PC’s firewall.

Could anyone suggests where the mistake might be? I am out of ideas now.

Thank you.

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Update #1:

I tried modifying the sendto() and successfully send data via “SEND_MAC” using a fixed MAC address (in register Sn_DHAR).

I suspect the ARP process has failed. Trying to isolate the network and narrow down the cause of this issue.

Be right back…

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Source: https://maker.wiznet.io/forum/11389