---
title: "W5500 IO Library hanging (no PING) - using http and snmp server code"
url: "https://maker.wiznet.io/forum/15955"
markdown_url: "https://maker.wiznet.io/forum/15955/md"
type: "Forum topic"
category: "IO Modules"
author: "allenhuffman"
created: "2025-12-18T02:10:43+09:00"
last_activity: "2026-06-25T22:09:46+09:00"
language: "en"
views: 5
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# W5500 IO Library hanging (no PING) - using http and snmp server code

## Question

Asked by allenhuffman on 2025-12-18 in IO Modules.

We use an W5500 chip. We have software from the github:

[Wiznet/ioLibrary_Driver: ioLibrary_Driver can be used for the application design of WIZnet TCP/IP chips as W5500, W5300, W5200, W5100, W5100S, W6100, W6300.](https://github.com/Wiznet/ioLibrary_Driver)

I blink a heartbeat LED in our main loop. It continues to operate, but sometimes the Ethernet stops responding to PINGs, or serving HTTP requests or SNMP requests.

Our main loop is making calls to:

```plaintext
httpServer_run(i);  // Process HTTP requests on each socket
snmpd_run();
```

Sometimes it can run overnight and still be responding. Other times, it stops -- no response from PING, etc.

What code could I use to check for this? What is the process to detect, and reset the I/O to work again?

Thank you.

## Replies

### Reply 1 by Grace_Koo, 2025-12-18

You can refer to the following WIZnet official examples and adapt their structure and socket handling logic to your application:

HTTP server example
<https://github.com/WIZnet-ioNIC/WIZnet-PICO-C/tree/main/examples/http/server>

SNTP example (periodic network communication and timeout handling)
<https://github.com/WIZnet-ioNIC/WIZnet-PICO-C/tree/main/examples/sntp>

These examples show how to structure the main loop, manage socket states, and handle periodic network tasks more robustly.

### Reply 2 by allenhuffman, 2026-06-25 (in reply to reply 1)

Thank you for this reply last year.

Neither of those examples have any code to detect if the network stack fails. They just sit in a loop calling the *_run() routine.

We have used Wiznet chips on three different designs so far, but this is the first one I have actually had time to test longevity with. Surely it cannot be common for the stock code to just hang if left running.

For our product, that won't be acceptable. I have a watchdog to catch lockups, but I need some way to probe the network stack and see if it is still alive.

---

Source: https://maker.wiznet.io/forum/15955