I have a newbe question.
I'm setting up a dashboard to monitor liquid in tanks. I will use 4 sensors to a digital pin on an Arduino then to rpi. In node-red after receiving the gpio If it's high I change it to .20, so I ether a 0(low) or .20(high) from each gpio after the changes. Here is where I stuck. How do I add the 4 gpio in the function node and get a total msg.payload?