I wonder if there is such a device (not pc based), has rj45 connector, and a few buttons, when a button is pressed, it will send a pre-configured tcp/udp packet to an ip ?

dont want any os based, as it need time to boot up, can corrupt, expensive too.

The built an entire tcp/ip stack you need an OS. Probably something like a Raspberry PI.

In order to send a TCP/UDP packet over ethernet, there are a not of handshaking need to be done before you are allowed to send.

if you have limited budget, will you consider 2nd hand device ?

P/S : most new computer does not equip with RJ45.
will you consider wifi ?

some raspberry pi model have both RJ45 and Wifi.





This post has been edited by flashang: Aug 9 2023, 11:06 AM

you could get away with a microcontroller like an Arduino with an ethernet shield.
another option, WT32-ETH01
If you're open to more tinkering, TP-Link TL-MR3020 with custom firmware

This post has been edited by KLKS: Aug 9 2023, 11:15 AM

then how ethernet / wifi relay works ?

https://shopee.com.my/product/912201353/198..._oaAiGEEALw_wcB

https://shopee.com.my/product/962270827/226..._oaAqYPEALw_wcB

https://shopee.com.my/product/957629053/235...OoaAha5EALw_wcB

those can work almost instantly after connected to power, can connect to them using tcp, send command to them and they turn relay on/off. they all cost below rm100, some even below rm20, they dont time to boot, i dont think they are pc/os based. I am looking for similar product that do the reverse thing.

Those are controller modules, they have their own micro controller.

Will automatically setup and acquire DHCP IP address and then broadcast about themselvs, so that they can be detected.

I have saw some using SNMP as well.

if send is possible, how much more difficult for them to do receive ?

From your original post, any microcontroller can done easily :
Read button and send command to an IP.

Receive are different process, many tutorial show how to do send / receive.

P/S : The 3 shopee products are totally different approach.





This post has been edited by flashang: Aug 9 2023, 11:12 PM