Hello everyone, I hope someone can give me some advice regarding a question I have based on the use of the RS-485 protocol.
It turns out that I have to do an automation project for a coffee drying rack, it must open or close depending on certain environmental variables, to carry it out it is necessary to sense rain, humidity, temperature, position of the rack, presence (in case there is someone nearby to stop the engine from running). The point is that due to the dimensions of the rack, the sensors will have to be located about 15 meters from the arduino. To solve the issue of distance I have seen that the RS-485 module can be used, but I have not found much information on its configuration when it is used only as an "extender", I have even thought that I should use an RS-485 module for each sensor, because it seems that the master-slave configuration only works -I understand- when microcontrollers are connected.
Postscript: Can all kinds of sensors be used with the RS-485 protocol?
RS-485 is not a protocol. It's only a special (differential) line driver that can be used to transmit logic signals over longer wires.
RS-485 modules can be used in half (alternate) or full (bidirectional) duplex transmission.
Multiple slaves can be connected to an RS-485 bus. Then the master controller has to enable one slave and tell it when to send data, by 2 additional wires. Or the master sends a slave ID and the addressed slave responds.
It's all up to you or some defined (MODBUS...) protocol how you use RS-485 signal transmission.
You do need some form of intelligence (i.e. microcontroller) connected to each sensor (i.e. slave) in order to convey the sensor readings when requested by the master. If several sensors are co-located, then they could all be connected to one microcontroller acting as a slave on the RS-485 bus.
You can probably use any sensor you can think of with an RS-485 bus. The key is that the sensor needs a way of sending or receiving on the RS-485 bus. That's where the microcontroller comes in.
There are some situations where RS-485 may not be appropriate due to the delays in reporting back to the master.
Your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for advice on (nor for problems with) your project.