MQTT topics

[ralphwetzel]

Peter --

I tried to use the MQTT nodes - and encountered some strange effects:

MQTT Sender (to be run on the MCU):

sender.json

```js [ { "id": "4dc6e91342cfdc95", "type": "tab", "label": "MQTT Sender", "disabled": false, "info": "", "env": [], "_mcu": { "mcu": true } }, { "id": "7e8450f889bc77e5", "type": "group", "z": "4dc6e91342cfdc95", "name": "Test: Send to MQTT", "style": { "label": true }, "nodes": [ "329f102a0e2672e9", "f7d2c588db6cf95c", "23d2e1e9ec0bf70e" ], "x": 494, "y": 139, "w": 552, "h": 82 }, { "id": "329f102a0e2672e9", "type": "function", "z": "4dc6e91342cfdc95", "g": "7e8450f889bc77e5", "name": "prepare for MQTT", "func": "// msg.topic == sensor.id\n\nlet values = {\n \"t1\": msg.data.t1,\n \"t2\": msg.data.t2,\n \"t3\": msg.payload\n}\n\nlet res = [];\n\nfor (let key in values) {\n if (values[key]) {\n let m = {\n \"topic\": `mqtt/test/${key}`,\n \"payload\": values[key]\n }\n res.push(m);\n }\n}\n\n// send a msg per value\nreturn [res];\n", "outputs": 1, "noerr": 0, "initialize": "", "finalize": "", "libs": [], "_mcu": { "mcu": true }, "x": 790, "y": 180, "wires": [ [ "f7d2c588db6cf95c", "7d8c6612a681c9cb" ] ], "inputLabels": [ "Sensor values" ], "outputLabels": [ "MQTT messages" ] }, { "id": "f7d2c588db6cf95c", "type": "mqtt out", "z": "4dc6e91342cfdc95", "g": "7e8450f889bc77e5", "name": "", "topic": "", "qos": "2", "retain": "false", "respTopic": "", "contentType": "", "userProps": "", "correl": "", "expiry": "", "broker": "4b0b89cd78b32db9", "_mcu": { "mcu": true }, "x": 970, "y": 180, "wires": [] }, { "id": "23d2e1e9ec0bf70e", "type": "inject", "z": "4dc6e91342cfdc95", "g": "7e8450f889bc77e5", "name": "", "props": [ { "p": "payload" }, { "p": "data", "v": "{}", "vt": "json" }, { "p": "data.t1", "v": "2", "vt": "str" }, { "p": "data.t2", "v": "3", "vt": "str" }, { "p": "topic", "vt": "str" } ], "repeat": "", "crontab": "", "once": false, "onceDelay": 0.1, "topic": "01", "payload": "1", "payloadType": "num", "_mcu": { "mcu": true }, "x": 590, "y": 180, "wires": [ [ "329f102a0e2672e9" ] ] }, { "id": "7d8c6612a681c9cb", "type": "debug", "z": "4dc6e91342cfdc95", "name": "debug 67", "active": true, "tosidebar": true, "console": false, "tostatus": false, "complete": "true", "targetType": "full", "statusVal": "", "statusType": "auto", "_mcu": { "mcu": true }, "x": 1020, "y": 300, "wires": [] }, { "id": "4b0b89cd78b32db9", "type": "mqtt-broker", "name": "", "broker": "192.168.178.72", "port": "1883", "clientid": "", "autoConnect": true, "usetls": false, "protocolVersion": "4", "keepalive": "60", "cleansession": true, "birthTopic": "", "birthQos": "0", "birthPayload": "", "birthMsg": {}, "closeTopic": "", "closeQos": "0", "closePayload": "", "closeMsg": {}, "willTopic": "", "willQos": "0", "willPayload": "", "willMsg": {}, "userProps": "", "sessionExpiry": "", "_mcu": { "mcu": false } } ] ```

MQTT Receiver (to be run as standard NR flow):

receiver.json

```js [ { "id": "df3521992a1ba688", "type": "tab", "label": "MQTT Receiver", "disabled": false, "info": "", "env": [], "_mcu": { "mcu": false } }, { "id": "e2e71ed681ee60da", "type": "mqtt in", "z": "df3521992a1ba688", "name": "", "topic": "mqtt/test/#", "qos": "2", "datatype": "auto-detect", "broker": "4b0b89cd78b32db9", "nl": false, "rap": true, "rh": 0, "inputs": 0, "_mcu": { "mcu": false }, "x": 291.6666564941406, "y": 224.99998474121094, "wires": [ [ "1f1bcb4d8b228924" ] ] }, { "id": "1f1bcb4d8b228924", "type": "debug", "z": "df3521992a1ba688", "name": "debug 68", "active": true, "tosidebar": true, "console": false, "tostatus": false, "complete": "true", "targetType": "full", "statusVal": "", "statusType": "auto", "_mcu": { "mcu": false }, "x": 521.6666564941406, "y": 224.99998474121094, "wires": [] }, { "id": "4b0b89cd78b32db9", "type": "mqtt-broker", "name": "", "broker": "192.168.178.72", "port": "1883", "clientid": "", "autoConnect": true, "usetls": false, "protocolVersion": "4", "keepalive": "60", "cleansession": true, "birthTopic": "", "birthQos": "0", "birthPayload": "", "birthMsg": {}, "closeTopic": "", "closeQos": "0", "closePayload": "", "closeMsg": {}, "willTopic": "", "willQos": "0", "willPayload": "", "willMsg": {}, "userProps": "", "sessionExpiry": "", "_mcu": { "mcu": false } } ] ```

👉 You need to configure the MQTT connection to adapt to your system!

Observations:

• When pushing the inject button for the first time, the sender emits the Debug messages, yet no data is received by the receiver.
• When pushing the inject button for the second time, the sender throws with /Users/ralph/Projekte/Moddable/moddable/examples/io/tcp/mqttclient/mqttclient.js (121) # Exception: MQTTClient.prototype.write: cannot coerce undefined to object!.

When both flows are run as standard NR flows, everything works as intended. Any proposals?

My system status: Moddable @ 758b624, node-red-mcu @ 6427d0e

[phoddie]

Thanks for the report. The problem appears to have that the sender was not handling the topic correctly in the configuration JSON. I've committed a fix and tested successfully with the test.mosquitto.org broker. nodered2mcu should be updated to normalize this, so the runtime doesn't have to.

[ralphwetzel]

Just tested this fix successfully. :+1: I propose to leave the report open until you put it into nodered2mcu.

[phoddie]

Thanks for the quick check! It makes sense to leave this open as a reminder to update nodered2mcu. I've done that just now and the changes will propagate out next week. As a nice side-effect, I found that the four private fields on the "mqtt in" node can be eliminated, which saves a bit of memory for each instance.

[phoddie]

The nodered2mcu updates are live, so I've committed the corresponding changes to the MQTT node implementation. I think we can close this out now?

[ralphwetzel]

Confirmed. 👍 Yes we can...