---
title: "WIZ107SR-TTL no response"
url: "https://maker.wiznet.io/forum/14171"
markdown_url: "https://maker.wiznet.io/forum/14171/md"
type: "Forum topic"
category: "Serial-to-Ethernet & ConfigTool"
author: "Mkozlicki"
created: "2021-02-28T14:04:15+09:00"
last_activity: "2021-02-28T20:02:10+09:00"
language: "en"
views: 454
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# WIZ107SR-TTL no response

## Question

Asked by Mkozlicki on 2021-02-28 in Serial-to-Ethernet & ConfigTool.

I have recently purchased 2 WZI107SR-TTL boards. I have powered them with 3,3V (power LED is on), but after connecting to switch or hub there is nothing happening on socket activity LEDs. I checked with different cables and switches. Is there anything special I need to do to start using the board?

Thanks

## Replies

### Reply 1 by eNDi, 2021-02-28

There is nothing special - just connect 3,3V and the Link-LED should show the connection status.
Is your 3,3V power source stable? Use a DSO to confirm, some regulator-boards can be really bad.
What’s the current consumption of the module?
What is connected to the other pins?

### Reply 2 by Mkozlicki, 2021-02-28

Thank you, was a power supply issue indeed.

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Source: https://maker.wiznet.io/forum/14171