---
title: "W5500 - multiple packets in TX buffer (UDP)"
url: "https://maker.wiznet.io/forum/14074"
markdown_url: "https://maker.wiznet.io/forum/14074/md"
type: "Forum topic"
category: "Ethernet Chips"
author: "Member 007"
created: "2020-11-28T16:18:02+09:00"
last_activity: "2020-12-10T10:21:18+09:00"
language: "en"
views: 379
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5500 - multiple packets in TX buffer (UDP)

## Question

Asked by Member 007 on 2020-11-28 in Ethernet Chips.

Hi,

I have a question regarding the W5500 TX buffer in UDP mode. Is the TX buffer designed for sending only one packet at a time or can I fill the TX buffer with multiple packets and the W5500 will send them out when it can?

One example of what I would like to do:

- 1. set the destination IP, PORT for packet #1

- 1. transfer the data to the W5500 TX FIFO for packet #1

- 1. Issue a SEND command for packet #1 and wait for it to be cleared by the W5500 hardware.

- 1. go back to step 1. (without waiting for the SEND_OK confirmation) and repeat the procedure for packet #2 and so on…

Is this possible? Does the W5500 know how to handle this situation? Or do I need to wait for the SEND_OK confirmation bit and only then begin the procedure of sending a new packet?

BR,
Tilen

## Replies

### Reply 1 by becky, 2020-12-10

Hello,
You need to wait for the SEND_OK.
Thank you.

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Source: https://maker.wiznet.io/forum/14074