MQTT subsciption to topic

Need Help With My Project
1

hi, i’m looking to mqtt subscribe to a variable status (an already data stream mqqt published) using
mosquitto_sub -h blynk.cloud -u ‘device’ -p 1883 -P ‘[device token]’ -t ‘ds/BatV’

do not receive acknowledge hence updates, any possible help on this?

Thanks,
Luis

2

Have you read the documentation?…

Pete.

3

Hi Pete, and thanks for your advice. Believe me, is always my first choice to look for the documentation before of placing a question. However in many cases it is not thoroughly clear so looking for someone that may have solve the problem is helpful. I had a similar issue when looking how to publish using the mqtt library for arduino and some guidances from you worked perfectly.
thanks anyway, will follow testing.
Luis

4

Okay, but the reason I asked was that there seems to be a very big difference between the syntax of the Blynk examples and the syntax you are using.

Although I use MQTT for all of my home automation communication, I don’t send data to Blynk in the same way that you are attempting to, I use the Node-Red plugin for Blynk instead.
I did try the Blynk native MQTT integration when it was introduced (which was fairly recently) and it did work for me, but I just followed the examples that were supplied.

Pete.

5

Thanks for the insight Pete. I use mqtt in all my logic, in fact publishing works fine, i had onboarded LoRa devices through a LoRa wan gw so recording information from those devices in my Blynk account. that sintaxis is the mqtt standard one that later let me replicate it in my arduino routines. Subscription is required for letting me to seamlessly migrate from Ubidots to blynk some solution already running. Anyway, will try harder. Luis

6

Your example is this…

The Blynk subscribe example from the documentation I linked looks like this…

Subscribe to all downlink messgaes

mosquitto_sub -L “mqtts://device:$BLYNK_AUTH_TOKEN@blynk.cloud/downlink/#” -F “%t: %p”

The “downlink” keyword in the subscribe command isn’t optional, yet you’re not using it and complaining that you’re unable to subscribe to a datastream.

Pete.