---
title: "Missing data packages when constantly transmitting with W5500"
url: "https://maker.wiznet.io/forum/14628"
markdown_url: "https://maker.wiznet.io/forum/14628/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "yoremkastor"
created: "2022-08-30T10:24:18+09:00"
last_activity: "2022-09-05T04:30:38+09:00"
language: "en"
views: 267
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# Missing data packages when constantly transmitting with W5500

## Question

Asked by yoremkastor on 2022-08-30 in Ethernet Chips.

Hello I have used iolibrary and example from here

[link](https://chowdera.com/2021/03/20210328093320388j.html)

to setup my ATSAMD21 curiosity nano and ETH WIZ clck. SAMD21/W5500 configures and connects to my pc. I can send and receive data.

When I was trying to see what can I achieve max with data rates I saw that while constantly transmitting I can not receive data sent from hercules sometimes.

I constantly transmit loop count in main as data. Which starts from 1 and increment whenever it loops.
I randomly send 1 byte of data which is character ‘0’ and It should toggle on board led. Onboard LED does not toggle sometimes…

## Replies

### Reply 1 by yoremkastor, 2022-08-30

I was using hercules I tried different software sockettest 3.0.0 and it seems to be problem with hercules not the embedded software.

### Reply 2 by irina, 2022-09-05 (in reply to reply 1)

Are you using the ioLibrary we provide?
The link is performance when ioLibrary and SPI communication use.
<https://docs.wiznet.io/Product/iEthernet/W5500/Application/spi-performance>

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Source: https://maker.wiznet.io/forum/14628