Looking for simple Ethernet (RJ-45) controlled on/off switch for low-voltage DC line

I need to replace a mechanical toggle on/off switch with one that can be controlled with a flavor of Ethernet (e.g. 10Base-T, 100Base-T, or 1000Base-T) using standard RJ-45 port.

The line in/out is just a low-voltage DC line controlling a fan.

I want my software to turn the fan on/off, and the software commands are sent out over Cat5e cable to an RJ-45 port.

I'm having trouble with search terms for Google. Something like: on/off switch with ethernet port, just returns a lot of ethernet switches of various port sizes. Or, I find lots of sites promoting how to add a mechanical toggle switch to an RJ-45 cable, which is opposite of what I'm trying to do.

Looking for a simple solution, and wonder if anyone has come across such a thing for their hobby projects.

• You could program a Nanode to do this very easily with a few external components (e.g. an NPN transistor a resistor, and a protection diode) – vicatcu Aug 30 '13 at 17:01
• Price Range? This is done alot in hobby projects for cheap, or expensively for retail devices. – Passerby Aug 31 '13 at 1:42

Good search terms would be "Ethernet Relay" or "Ethernet I/O".

A quick search turned up several possibilities. An interesting on was from www.relaypros.com, look in the "Wired Relay" -> "Ethernet Interface" category.

I am sure there are other possibilities; this approach would be a little less work than creating your own with a microcontroller based board.

• @B Pete, You took @theamk XPORT recommendation and included the relay! Much simpler, thanks. – ggkmath Aug 30 '13 at 19:16

what you want is called "ethernet to GPIO" and it is a side function of many ethernet<->serial converter.

For example, Lantronix XPORT is a nice, cheap ethernet-serial module. It has a serial port (which you can ignore) and 3 "software selectable PIO pins" which is just what you need. Each of these pins can be set to low or high voltage under ethernet control. Those pins are 3.3v output only, but with "3.3v relay board" (google it!) you can easily control larger loads.

Easiest solution (in terms of time/money/complexity) would be a Raspberry Pi with an IO board.

• Would I need to program it myself, or does it ship containing instructions my computer can use to interface to it with, to control a DC line that connects to the board? – ggkmath Aug 30 '13 at 15:58
• Looks fairly plug and play to me, although you can DIY it as much or as little as you like: www2.milocreek.com:8080 – John U Aug 30 '13 at 16:28
• Whilst the Raspberry Pi can play HD video out of the box when you add a PSU, HDMI lead, keyboard, mouse. mine did not ship with instructions to turn on a relay. Neither did it have a relay to turn on. It is awesome but it's not equipped to do this out of the box but you can certainly do this and a whole bunch more with the right equipment and programming. – Spoon Aug 30 '13 at 19:43
• @Spoon John did say with an IO Board. – Passerby Aug 31 '13 at 1:40
• My appologies for the post,it was a bit flipant. I'd love an out of the box solution with software ready to be installed on the pi however when the box turns up and you plug it in there still needs to be software installed and configured (using extra keyboard, mouse, tv etc.) The solution suggested by B Pete is much simpler and easy to implement. Using the pi requires more time and effort to understand. The two answers together are good examples of choices you have. Time(and effort) v Money ... which one is the most limited resource determines the correct answer for a given situation. – Spoon Aug 31 '13 at 8:57