I'm a new comer to the Raspberry Pi scene.
I'm looking to create a device that can monitor up to 20 temperature sensors every 1 minute with 20 meters of cabling per sensor for my mini green-houses. The green houses are only about 1x1meter in length/width and are placed in groups, i.e. down the left hand side of the garden, right hand side and some in the house.
I've seen that the DS18B20 sensor uses the 1-Wire bus that allows multiple sensors, but it's only supposed to be used over short distances. The hardware supplier had provided the following guidance, although I'm still finding it somewhat cryptic.
https://www.maximintegrated.com/en/desi ... 1/148.html.
Using 20 sensors with 20 meters of cabling each would essentially give 400 meters of weight, which seems incredibly heavy.
Instead, I saw on the "Switched Networks" section of the supplier guidance that I could potentially isolate the temperature sensors in smaller groups and switch them on and off to reduce interference. Perhaps reduce them down to 5 sensors per group? I'm not entirely sure how I would go about creating that functionality to turn each group on then off in sequence? I might be way off the mark here.
I've attached a diagram on how the physical layout of the sensors is grouped. The green squares are the green houses and the red square is the Raspberry Pi. The reason I'm looking for 20 meters, is because the green houses often get moved, so it wouldn't be ideal if the cables are a fixed length. This would mean there is a lot more cable mess around though...
I was planning on using the following:
[*] Raspberry Pi 3 Model B+.
[*] Edimax Wifi USB adapter so I can place it about 30 meters from the Internet router in the house.
[*] 20 x DS18B20 (waterproof) with 20 meter cable of CAT5 cable.
[*] Breadboard for inserting the CAT5 cable ends and hooking up to the Raspberry Pi.
[*] 4.7k pull-up resistor.
Any help would be greatly appreciated before I make a purchase of sensors.