How to daisy chain LOTS of sensors together with CAT7 cable?

Hey everyone

I am trying to build home automation network that contains lots of temperature sensors and motion sensors and all kinds of other sensors, and have them all wired together with 1 cable, preferably CAT 7 cable for ease of use since they are shielded and not that expensive.

Main unit would be raspberry pi 3 or arduino, and I was thinking of each sensor nodes to be arduinos, but now im at the point of thinking if i even need arduinos at sensor nodes? If i know correctly, I could just use 1-wire protocol and use Power over ethernet, and have 1 POE splitter at each sensor node? Do i even need micro-controllers at each sensor with that kind of setup?

The way i was thinking was this:
Raspberry pi3 / Arduino > POE injector > CAT7 cable > POE splitter > DC Power Splitter AND Ethernet splitter (so that i can daisy chain further) > DHT22 sensor

would this work? :slight_smile: Or how would you do this?

Im trying to do something similar to Growtronix, which daisy chains sensors for agricultural environment, for growing vegetables and such... Well I want to do something similar but for home automation. And they use serial port for computers so they most likely use 1-wire protocol right?

If you intend to use Ethernet style devices, you will need an Ethernet interface (arduino/pi), you won't be able to use anything like 1-wire directly over the cable if it connects with a 'real' Ethernet socket.
You could come up with a DIY solution, but it isn't worth the effort for the price of Arduinos. The Ethernet port provides isolation from the cable which ideally you'd want to replicate via optos (or magnetics) and isolated DC-DC converters for the power (if it's POE, or should I say POcat7?)
Network cables have 8 wires, so you wouldn't be limited to a 1-wire solution if you did go the custom route.

If I went the custom route, I'd use RS485 ICs (SP491 for example) with isolation on the arduino side (ADUM4400 series are very nice).

Serial ports on computers are RS232 and use the RS232 'protocol' (I use the term loosely). You need more than 1 wire for these. It's difficult to guess what the growtronix uses, it's something custom though.

yeah, i most definitely intend it to connect via real ethernet interface, RJ45 socket. I thought I could just use wires from RJ45 socket to make 1-Wire network, well I guess its not that simple then. i do have spare arduinos so thats not a big deal if i do need to use them.

I do have a bunch of Mini ENC28J60, for easy ethernet with arduinos

Yes if i go with arduinos, then i need DC-DC converters. Not sure what you mean with optos or magnetics? Or why would i need RS485 ICs or SP491 or ADUM4400? I kind of thought ENC28J60 is enough to just plug those connections in arduino?

would this fit anywhere in this picture? DS2413 1-Wire Two GPIO Controller Breakout Would i need to order a few of those to be used for 1-Wire interface?

Those parts may only be required if you were going a DIY custom route, using the cat7 cables for you own purposes and not as a network, for routing 1-wire. So ignore all of that :smiley:
You won't really need DC-DC converters either, POE should remain isolated if you use that, or use localised AC-DC converters.

What sensors are you intending to use? That will dictate what (if any) hardware you will need to add to the Arduino to talk to it/them. The DH2T2 should work directly with a couple of resistors (most circuits show 1 resistor, but I'd add a 2nd one in-line from the output of the arduino of 100R, for those times when something unexpected happens :slight_smile: ) (I couldn't find data on the maximum current allowed on the data pin, so I took a guess, it's better than nothing :slight_smile: ).

Yes, I've just remembered that Arduinos can be powered with up to 12volts, so i can scrap DC-DC converters.

For now i'm intending to use
-DHT22
-HC-SR501 motion sensor
-Photosensitive Light Sensor
-8 channel relays
-4 channel relays
-Float water level sensors
-water flow sensor

nothing that fancy basically, they are all simple sensors, except for relays, they do need 4 or 8 signals...

I've been leaning towards RS485 protocol as of lately, instead of CAT7 cables. it seems MUCH easier to use, without any splitters and injectors etc etc... and i can use custom 3 or 4 pin wires that are much thicker than CAT7 wires, so that i can mitigate long distance power loss.

Anyone here have experience with RS485? :slight_smile: