Up until now I've been using an HS3 plugin to poll PurpleAir sensors but I decided to re-implement this in Node-RED instead of paying to upgrade to the HS4 version of the plugin. I also like the fact that I can see and control exactly what's going on with the response processing and that nothing is "hidden" behind a plugin curtain.
The flow uses a recurring inject node to trigger polling every 10 minutes. The polling is done with an HTTP Request node. The trigger is delayed 2 seconds between the request nodes just to keep PurpleAir from getting upset with too many requests in a short period of time. This delay also allows the results to be processed by the same change node and finally routed to the HS Device nodes with a switch node.
With the exception of the change node, the other nodes are basic and straightforward. The request nodes should be set to return a parsed JSON object in msg.payload. Note that the sensors I'm showing here are sensors I randomly picked out in the framing community of Modesto, CA.
The change node moves msg.payload to msg.save, which is generally a good idea so that nothing in the JSON payload affects follow-on nodes that unexpectedly may interpret the msg. It then sets up the new message for the HS Device node and also sets msg.sensor_id to ID of the PurpleAir sensor.
The switch node routes the msg to the appropriate HS Device node based on msg.sensor_id that was set by the change node.
The flow uses a recurring inject node to trigger polling every 10 minutes. The polling is done with an HTTP Request node. The trigger is delayed 2 seconds between the request nodes just to keep PurpleAir from getting upset with too many requests in a short period of time. This delay also allows the results to be processed by the same change node and finally routed to the HS Device nodes with a switch node.
With the exception of the change node, the other nodes are basic and straightforward. The request nodes should be set to return a parsed JSON object in msg.payload. Note that the sensors I'm showing here are sensors I randomly picked out in the framing community of Modesto, CA.
The change node moves msg.payload to msg.save, which is generally a good idea so that nothing in the JSON payload affects follow-on nodes that unexpectedly may interpret the msg. It then sets up the new message for the HS Device node and also sets msg.sensor_id to ID of the PurpleAir sensor.
The switch node routes the msg to the appropriate HS Device node based on msg.sensor_id that was set by the change node.
Code:
[
{
"id": "76915431a1cecbc2",
"type": "tab",
"label": "PurpleAir",
"disabled": false,
"info": "",
"env": []
},
{
"id": "157fe75fbc04079e",
"type": "http request",
"z": "76915431a1cecbc2",
"name": "Poll 73501",
"method": "GET",
"ret": "obj",
"paytoqs": "ignore",
"url": "https://www.purpleair.com/json?show=73501",
"tls": "",
"persist": false,
"proxy": "",
"authType": "",
"senderr": false,
"x": 510,
"y": 180,
"wires": [
[
"62d6719dee1a7ad8"
]
]
},
{
"id": "02a654e63f671d92",
"type": "inject",
"z": "76915431a1cecbc2",
"name": "Polling Trigger",
"props": [
{
"p": "payload"
},
{
"p": "topic",
"vt": "str"
}
],
"repeat": "600",
"crontab": "",
"once": true,
"onceDelay": "5",
"topic": "",
"payload": "",
"payloadType": "date",
"x": 120,
"y": 180,
"wires": [
[
"157fe75fbc04079e",
"25a17ec1df5b53cd"
]
]
},
{
"id": "acfee28bda839a3d",
"type": "http request",
"z": "76915431a1cecbc2",
"name": "Poll 13489",
"method": "GET",
"ret": "obj",
"paytoqs": "ignore",
"url": "https://www.purpleair.com/json?show=13489",
"tls": "",
"persist": false,
"proxy": "",
"authType": "",
"senderr": false,
"x": 510,
"y": 220,
"wires": [
[
"62d6719dee1a7ad8"
]
]
},
{
"id": "498c17d0e80b2513",
"type": "hs-device",
"z": "76915431a1cecbc2",
"name": "Aurora",
"device": "55",
"server": "cca8073e1d5285f1",
"feature": "56",
"reportonstartup": false,
"x": 1110,
"y": 180,
"wires": [
[]
]
},
{
"id": "c2603bb730b922f8",
"type": "debug",
"z": "76915431a1cecbc2",
"name": "",
"active": false,
"tosidebar": true,
"console": false,
"tostatus": false,
"complete": "true",
"targetType": "full",
"statusVal": "",
"statusType": "auto",
"x": 930,
"y": 140,
"wires": []
},
{
"id": "62d6719dee1a7ad8",
"type": "change",
"z": "76915431a1cecbc2",
"name": "",
"rules": [
{
"t": "move",
"p": "payload",
"pt": "msg",
"to": "save",
"tot": "msg"
},
{
"t": "set",
"p": "topic",
"pt": "msg",
"to": "update",
"tot": "str"
},
{
"t": "set",
"p": "payload.value",
"pt": "msg",
"to": "save.results[0].PM2_5Value",
"tot": "msg"
},
{
"t": "set",
"p": "payload.status",
"pt": "msg",
"to": "save.results[0].PM2_5Value",
"tot": "msg"
},
{
"t": "set",
"p": "sensor_id",
"pt": "msg",
"to": "save.results[0].ID",
"tot": "msg"
}
],
"action": "",
"property": "",
"from": "",
"to": "",
"reg": false,
"x": 740,
"y": 200,
"wires": [
[
"80b0b6e2904278a6",
"c2603bb730b922f8"
]
]
},
{
"id": "41d3c92200d53d66",
"type": "hs-device",
"z": "76915431a1cecbc2",
"name": "AMTS Modesto",
"device": "55",
"server": "cca8073e1d5285f1",
"feature": "58",
"reportonstartup": false,
"x": 1140,
"y": 240,
"wires": [
[]
]
},
{
"id": "25a17ec1df5b53cd",
"type": "delay",
"z": "76915431a1cecbc2",
"name": "2 Secs",
"pauseType": "delay",
"timeout": "2",
"timeoutUnits": "seconds",
"rate": "1",
"nbRateUnits": "1",
"rateUnits": "second",
"randomFirst": "1",
"randomLast": "5",
"randomUnits": "seconds",
"drop": false,
"allowrate": false,
"outputs": 1,
"x": 330,
"y": 220,
"wires": [
[
"acfee28bda839a3d"
]
]
},
{
"id": "80b0b6e2904278a6",
"type": "switch",
"z": "76915431a1cecbc2",
"name": "",
"property": "sensor_id",
"propertyType": "msg",
"rules": [
{
"t": "eq",
"v": "73501",
"vt": "str"
},
{
"t": "eq",
"v": "13489",
"vt": "str"
}
],
"checkall": "true",
"repair": false,
"outputs": 2,
"x": 930,
"y": 200,
"wires": [
[
"498c17d0e80b2513"
],
[
"41d3c92200d53d66"
]
]
},
{
"id": "cca8073e1d5285f1",
"type": "hs-server",
"name": "HS4Pi",
"host": "172.29.1.17",
"port": "80"
}
]
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