EG915U - Maximum payload size in MQTT topic subscribed

IoT Modules LTE Standard Module
1

Hi everyone!

I’m developing an application with the EG915U module to create an MQTT connection and exchange data.
From the MQTT connection I need to receive a large amount of data (about 16kbytes) from a topic in subscribe but, if the number of bytes to receive is higher than 1500/2000 (experimentally tested), the reception is not always successful, the module sends nothing out and stuks; sometimes sends the +QMTSTAT message to indicate that the MQTT connection has been closed.

Is there a maximum byte limit that the module can receive from a topic in subscribe? I tried looking in the manuals and online but couldn’t find anything about it.

Thanks in advance.
Bye!

2

Hi, may I ask what firmware version you are using now? You can use AT+QGMR query, thank you.

3

Thanks for your replay!

I did the tests with firmware version EG915UEUABR02A05M08 and after updating firmware with file EG915UEUABR02A08M08_01.001.01.001.zip, but problem persists.

4

Hi,
The current version of the EG915U module has a maximum reception limit of 20K for Standard Edition, but be careful that mqtt headers do not exceed 1K.Hope this helpful.

5

Ok thanks for the reply.
You wrote “EG915U module has a maximum reception limit of 20K” for the lenght of variable header, right? But which MQTT command could have a variable header that exceed the 1K size?