Maximum MQTT payload size

[Andrew Holt]

Hi,

I'm writing a C++ client to take data, Such as the STATUS in json and log it.

My question is what is the largest payload that a Tasmota MQTT message can send.

Thanks,

Andrew

[Philip Knowles]

I know that I’ve read somewhere in Tasmota about exceeding the MQTT message limit but can’t find it.

The longest message on my system is 29,146 bytes from a ZigBee Bridge but typically around 350 bytes from a TH16 with 5 DS18B20s attached.

It may be easier to use node-red just to subscribe to the topics that you want to monitor.

 

Regards

 

Phil K

 

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[Jon Bartlett]

I've read it's 65536B for the topic, and the largest size of entire payload is 256MB in the mqtt specs.

I don't know if Tasmota has smaller implementation though....

[Philip Knowles]

Tasmota has 100 character limit for the topic string (but that has placeholders) so the actual topic could be longer

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From: sonof...@googlegroups.com <sonof...@googlegroups.com> on behalf of Jon Bartlett <jon.bar...@gmail.com>
Sent: Thursday, November 18, 2021 7:28:24 AM
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Subject: Re: Maximum MQTT payload size

 

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