CHAPTER 4 ■ COMPLEX FLOWS: NODE-RED
Change the name to Check Threshold. By default, there will be only one path, so
click on the + Rule button to add a new path. If the sensor value is greater than 750, it will
follow path 1; otherwise, it will follow path 2. Path 2 will not check any conditions, so you
can change it to otherwise from the dropdown.
Node-RED keeps all input information in msg.payload. You will be sending the
sensor value in requestVar from Arduino, which is why the condition checks msg.
payload.requestVar.
Connect your Convert to Number and Check Threshold nodes.
You are going to use the sensor value to create a tweet message. Drag and drop a function
node on to the flow diagram. Place it after the Check Threshold node, as shown in Figure 4-17.
Figure 4-16. Switch node properties dialog box