[image] I am using a vibration sensor which is connected through modbus rtu to lorawan end node and end node is in turn connected with the lorawan gateway.so can i send modbus commands from node red platform to query the sensor values.? This image shows data received from sensor when giving modbu…

Hello Steve its really nice to meet u after long time, sensor is sending in 8 bytes 01-dev id 03-function code(holding registers) 1a 00006cea-operational status 42bfd4de-total acceleration 3eac8b33-x axis velocity 3ea752963-y axis velocity 3ea9eda2-z axis velocity 41d9febd-temperature 428…

[image] bachloo.rahul: Steve which are those nodes which dynamically read modbus registers modbus-getter and/or modbus-flex-getter nodes in the node-red-contrib-modbus package

Steve but how would the flow be wired with mqtt node so that it sends commands to gateway which in turn sends the commands to sensor.can u create some dummy flow which explains my case.?

[image] bachloo.rahul: Steve but how would the flow be wired with mqtt node so that it sends commands to gateway (1) MQTT in --> (2) [something that converts the MQTT payload to a flex getter request object] --> (3) modbus getter --> (4) [something that converts result into sensible values …

[image] -This is how we send downlink command to query modbus sensor. [image] [image] [image] [{"id":"d7118925.a9f4d8","type":"function","z":"9e668262.26725","name":"","func":"msg.payload =\n{\n 'fc':3,\n 'unitid':1,\n 'address':40001,\n 'quantity':20\n}\nreturn msg;","outputs":1,"n…

If you can do this by inject node, then send the EXACT same payload via MQTT Alternatively, if you only send part of the value via MQTT, send that to a function or template node or change node and build the correct object so that it 100% matches the object you have working in the inject.

Steve according to you But what is the definition of correct object in this case.what all parameters should be taken into consideration while sending the payload to lorawan gateway?

[image] bachloo.rahul: But what is the definition of correct object in this case I have no idea. I dont know what you are trying to achieve. your question was... "Want to query modbus via MQTT" So i said... [image] Steve-Mcl: Node-red supports MQTT Node-red can communicate to modbus …

Steve i think you already know what i am asking , basically earlier we used to send modbus commands form gateways web interface to query the sensor values. Now we want to send downlink commands(scheduler in hmi terms) to query the senosr values every 3 seconds from node red platform.for which u said…

Want to query modbus sensor via mqtt

General

bachloo.rahul 9 March 2021 15:29 9

Steve how would the message structure be like?as we have to include device_eui, type(hex), Payload(modbus cmd), port for sending a downlink command.And I am not sure why we are using mqtt input node as we can directly do it by an inject node with mqtt out node by making data-type as JSON.Am i missing something?.

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Want to query modbus sensor via mqtt

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