如何在Node-RED中通过比较控制的开关节点发送指定HTTP请求控制Pokeys57e

Hey Brendan, here's a straightforward, no-fuss way to swap out those limited pre-built nodes and get your relay control working exactly like the browser URL you tested:

1. Keep Your Existing Comparison Logic #

First, hold onto the node you’re using for the greater/less than check (whether that’s a Switch node or a custom Function node). We just need to redirect what happens after the condition is met—no need to rebuild your core logic.

2. Add an HTTP Request Node #

Drag an HTTP Request node from the Node-RED palette into your flow. Configure it with these settings:

• Method: Select GET (matches how your browser sends the request)
• URL: Leave this blank for now (we’ll set it dynamically based on your condition)
• Return: Pick a UTF-8 string (you don’t need the response content, but this is a safe default)

3. Dynamically Set the Request URL #

You’ll need to toggle the State parameter (1 for on, 0 for off) based on your comparison result. Here are two simple ways to do this:

Option A: Switch + Change Nodes (No Code Needed) #

• Connect your comparison node to a Switch node. Split the flow into two branches: one for when your condition is true (e.g., payload > 50) and one for when it’s false.
• Add a Change node to each branch:
  • For the "true" branch: Set msg.url to http://192.168.0.2/setS.html?Sensor=00&State=1&u=user&p=pass
  • For the "false" branch: Set msg.url to http://192.168.0.2/setS.html?Sensor=00&State=0&u=user&p=pass
• Link both Change nodes to your HTTP Request node.

Option B: Function Node (For More Flexibility) #

If you prefer a bit of code for tighter control, replace the Switch/Change setup with a single Function node:

// Replace "yourThreshold" with the actual number you’re comparing against
if (msg.payload > yourThreshold) {
    msg.url = "http://192.168.0.2/setS.html?Sensor=00&State=1&u=user&p=pass";
} else {
    msg.url = "http://192.168.0.2/setS.html?Sensor=00&State=0&u=user&p=pass";
}
return msg;

• Connect your comparison node to this Function node, then link the Function node to the HTTP Request node.

4. Test and Deploy #

Hit deploy, then trigger the condition that should activate the relay. You can add a Debug node after the HTTP Request node to verify the request is sending correctly—but since your browser URL works, this should function exactly as expected.

Bonus: Optional Error Handling #

If you want to catch cases where the Pokeys57e is offline or unresponsive, connect a Catch node to the HTTP Request node to log errors or trigger alerts.

内容的提问来源于stack exchange，提问作者Brendan Kirk