Quectel EC200U-CNAA problem with Json format data posting to MQTT Server

Technical Subjects
1

Hi,
Iam using Quectel EC200U-CNAA with firmware version of EC200UCNAAR02A05M08, problem iam facing with to Post Json format data to MQTT server.

Iam followed by the below AT commands

AT+QMTCFG=“will”,0 Response OK

AT+QMTOPEN=0,“mqttserver_name”,1883 Response OK +QMTOPEN: 0,0

AT+QMTCONN=0,“client_name”,“username”,“password” Response OK +QMTCONN: 0,0,0

AT+QMTPUB=0,0,0,0,“mqtt_publish_topic”,9,“Test_MQTT” Response OK +QMTPUB: 0,0,0

everything has been OK with the above, while iam trying to post Json format data modem throughing error like +CME ERROR 58

AT+QMTPUB=0,0,0,0,“mqtt_publish_topic”,16,“{“mqtt”:“test1”}”

Response +CME ERROR: 58

Suggestion Please,

2

problem with json double quote, “{"mqtt":"test1"}”

3

First of all thanks for the response. Yes, Linh_Bul i understand. my doubt is whether quectel EC200U-CN modem does support Json format or Not. because “JSON framework must be constructed with double-quotes". but I tried with escape character it can able to Post like below.

AT+QMTPUB=0,0,0,0,“mqtt_publish_topic”,20,“{"mqtt":"test1"}”
OK
+QMTPUB: 0,0,0

Thanks,