---
title: "WIZ105SR TX output signal tri-state?"
url: "https://maker.wiznet.io/forum/11639"
markdown_url: "https://maker.wiznet.io/forum/11639/md"
type: "Forum topic"
category: "Serial-to-Ethernet & ConfigTool"
author: "samvjt"
created: "2016-02-01T22:07:13+09:00"
last_activity: "2017-05-04T08:38:10+09:00"
language: "en"
views: 533
replies: 1
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# WIZ105SR TX output signal tri-state?

## Question

Asked by samvjt on 2016-02-01 in Serial-to-Ethernet & ConfigTool.

Somewhere I got the idea that the TX output of the TCP-to-serial module is hi-z while TCP is not connected, and it only drives LO or HI while TCP is connected.
This kind of tri-state operation could be useful in some applications.
(If the tri-state feature is not used, a pulldown resistor is needed on the output.)
Is the TX output of the WIZ105SR module tri-state, or is it always active?

## Replies

### Reply 1 by jim, 2016-02-02

Dear samvjt

I think your idea is cool.
But there is a risk.
I suggest WIZ550S2E module with the status pin of connection.
[url][http://www.wiznet.co.kr/product-item/wiz550s2e/\[/url\]](http://www.wiznet.co.kr/product-item/wiz550s2e/%5B/url%5D)

Thanks.

---

Source: https://maker.wiznet.io/forum/11639