5V solenoid water valve + relay. Workflow: Arduino checks moisture and sends readings to the Pi. A Python script on the Pi decides when to open the valve. Use systemd to run the monitoring script as a ...

Welcome to my quick review of an inexpensive 2-channel 5V relay module controlled via RS485 bus utilizing Modbus RTU protocol. As claimed by some online sellers, this easy-to-get Modbus RTU 2-Channel ...

When the button is pressed the Arduino board will put pin 2 in HIGH state, meaning 5V on pin 2. This voltage is used to drive the transistor that will switch ON the relay and the load (in our case the ...