20 temperature sensors to one MEGA 2560


Is it possible to connect 20 individual temperature sensors to one MEGA 2560? I have looked for 1-wire or PT1000 shields but haven't found any good options.

Do you guys have any ideas? :)

It depends on the kind of sensors/modules, and the area to cover. Weak temperature signals on many and long lines, and added multiplexers, will not result in reliable values. For intelligent digital sensors (I2C, 1-wire...) the extent of the network still is critical.

I'd use multiple (small) Arduinos, to collect the temperatures in a small area, then transmit everything to the central controller.

There won’t be long cables, I want to measure all in/out floor circuits, and also Primary in/out from the shunt.
Perhaps 1 meter each at most.

Was thinking of DS18B20, is that a good choice? I want it quite accurate.

Yes, DS18B20 seems feasible. You have just follow the rules for 1-Wire. Probably it is possible to cover all sensors with the only one pin if the cable can go from one to another.

Thanks, okey there's only 1 pc of 1-wire input on the 2560? How would the connection look like in schematics when connected the sensors in "series"?

It won't be problem powering the sensors from arduino?

1W is a bus so each sensor is "sitting" on 3 or 2 wires (VCC, DATA, GND). Vcc is optional. Google will find you lots of pictures. The best practise is to have cable without stubs as I wrote above "from one sensor to another". Power consumption for 20 sensor would not exceeds 100mA. It is able sink directly from the Arduino but in dependance on use of other devices you can use external power. In any case you should read the datasheet for DS18B20.