Using Cat5 Cable for communications with Arduino

You need to remember that Cat5 cable is a transmission line and has a characteristic impedance of 100ohms

If your driving a signal through a long length you need to drive with the right impedance (100ohm source impedance) and also terminate correctly (100ohm load). If not you will get reflections and things will end in tears

Do you have power at the relay end or are you also planning on delivering the power over the same Cat5 cable, if so you also need to consider that you will drop voltage over its length also and it will be susceptible to noise if not correctly terminated

If you are placing a low end controller with each relay board, you could use an Ethernet adapter for communications and also have the option to remote temperature and humidity sense among other things.

Just a though

I was not planning to put a controller at each point

these relay panels will be located in areas where I will not be interested in having sensors or additional processing.

That being said I have considered it however I do not currently have a large enough quantity of controllers or ethernet adapters to do what I would like to do.

The panels will each have 12v and 5v supplied locally so the only thing I need in the communication cable is the signal and the ground.

I would consider using other cable, possibly standard 4 conductor phone wire instead if that would make the signal more reliable.

the greatest run I am looking at will be right around 30 feet. probably a little less.

no matter what cable you use it will need to be terminated correctly if you want it to be reliable. Cat5 is reliable and a known characteristic (100Ohm), as I said you just need to drive it correctly

Using an RS485 line driver at each end may do the trick but you may be up to the cost of a low cost Uno and ENC Ethernet card so not worth the effort ?

just a thought

regards

Peter

I was going through my stuff and found (I forgot I had) a bunch of Arduino Pro Minis

These are the ones without USB.

I have not tinkered with them yet, I also do have 2 ENC Ethernet cards I forgot I bought.

One is the normal ENC28J60 and the other is a mini ENC28J60

I also have not yet had a chance to tinker with either of these.

My understand is these are 3.3v ONLY.

Which means I will need to get a level converter for each of them.

I do have one 3.3v Pro Mini but I was holding that for another project that will be using all 3.3v components.

Maybe I will use that board to tinker with the ENC just to get an understanding of how they work.

Can you point me toward a good but cheap logic lever converter that will work with the ENC?

I think you may find the ENC boards are 5V tolerant on the data lines, you just need 3V3 on the Power. I have never used a level converter on the UNOs I have plugged the ENC into

Ok, well that makes things a whole lot easier.

Now all I need to do is learn a WHOLE LOT about getting my Arduino Mega to communicate commands to the other boards.

Since I know almost nothing about networking this should get interesting.

I guess my first step should be making sure that my ENC boards and my Pro Mini boards are all working.

I also need to figure out how to upload sketches to the minis using arduino UNO as the interface

So I guess I have a lot of work to do, well it will come along eventually.

Whole bunch of good stuff here, need some time to watch it and try out the code but it should help alot

http://www.element14.com/community/groups/arduino/blog/2014/06/09/fast-track-to-arduino-programming

There my tutorials and I do cover off using the Ethernet (ENC and WIZNET) and also responding to commands and sending responses over serial and Ethernet.

Enjoy

I will definitely be looking at those tutorials.

First I need to figure out what I am doing with the Pro Minis.

I bought a bunch of them at the beginning of the year for a project I was doing for someone

I have about 5 left, Now I just need to remember how to program them.

Then I need to look at those ENC boards.

I need to make sure the 2 I have will work with what I am using, then I will start looking at your stuff

the final will be a main central control (an arduino mega with a 5100 shield) and 2 pro minis with ENC boards running the relays.

Eventually I am going to get a couple more of the ENC boards and use a couple more of the Pro Minis for control interfaces in remote locations.

This will be a complex project but it is very easily broken into smaller components so i will work on each smaller component and make sure I have one thing working before moving on to another interconnecting piece. I am actually going to save the central control till last as that will be the most difficult for me as far as the programming goes.

It will be a long process.

I have a project I've been working on for a while now with a friend of mine in the UK, we have over 10 remote sensor nodes to a master controller with power control, Temp sensing, humidity (Inside and Out), PWM, Infra-red remote and everything, including the use of ENC and the NRF24L01 boards for talking to the nodes rather than the ENC (NRF don't need the wires and are real cheap)

oh and Tablet / Smart Phone remote access (UK to Spain for instance)

So if you get stuck, feel free to ask away

I realized I have a few NRF24L01 boards and I may make use of them for my remote control panels.

I have yet to successfully get them working, maybe I have not yet found the right tutorial.

Hoping yours will make things make more sense to me.

I also have a couple 433mhz transmitters and receivers.

I would consider using those as well, but not sure exactly what for yet.