SimCom SIM7800 Series User Manual

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SIM7500_SIM7600_SIM7800 Series_MQTT_AT Command Manual 23 / 41
+CMQTTSUB: <client_index>,<err>
b)If failed:
OK
+CMQTTSUB: <client_index>,<err>
c)If failed:
+CMQTTSUB: <client_index>,<err>
ERROR
d)If failed:
ERROR
Defined Values
<client_index>
A numeric parameter that identifies a client. The range of permitted
values is 0 to 1.
<req_length>
The length of input topic data. The message
topic should be
UTF-encoded string. The range is from 1 to 1024 bytes.
<qos>
The publish message’s qos. The range is from 0 to 2.
0 – at most once
1 – at least once
2 – exactly once
<dup>
The dup flag to the message. The value is 0 or 1. The default value
is 0. The flag is set when the client or server attempts to re-deliver
a message.
<err>
The result code: 0 is success. Other values are failure. Please refer
to chapter 2.3.1.
2.2.15 AT+CMQTTUNSUBTOPIC Input the topic of unsubscribe message
AT+CMQTTUNSUBTOPIC is used to input the topic of a unsubscribe message.
NOTE: The topic will be clean after execute AT+CMQTTUNSUB.
AT+CMQTTUNSUBTOPIC Input a unsubscribe message topic
Test Command
AT+CMQTTUNSUBTOPIC=?
Response
+CMQTTUNSUBTOPIC: (0-1),(1-1024)
OK
Write Command
AT+CMQTTUNSUBTOPIC=<client_ind
Response
a)If successfully:

SimCom SIM7800 Series Specifications

General

Brand	SimCom
Model	SIM7800 Series
Category	Control Unit
Language	English

Summary

Introduction to MQTT AT Commands

1.1 SSL Context Management for SSL/TLS MQTT

Explains AT commands for managing SSL context for MQTT.

1.2 Process of Using MQTT AT Commands

Outlines the steps for using MQTT AT commands in sequence.

MQTT AT Command Reference

2.1 SSL Context Management AT Commands

Details AT commands for configuring SSL contexts for secure MQTT connections.

2.2 MQTT Services AT Commands

Covers AT commands for starting, stopping, and managing MQTT client services.

2.3 Command Result and Unsolicited Codes

Lists all command result codes and unsolicited codes for MQTT operations.

MQTT Usage Examples

3.1 Access MQTT Server (Not SSL/TLS)

Demonstrates connecting to an MQTT server without SSL/TLS.

3.2 Connect to SSL/TLS MQTT Server (No Server Verification)

Shows connecting to SSL/TLS MQTT server without verifying the server.

3.3 Access SSL/TLS MQTT Server (Verify Server Only)

Details accessing SSL/TLS MQTT server with server verification.

3.4 Access SSL/TLS MQTT Server (Verify Server and Client)

Illustrates connecting to SSL/TLS MQTT server with both server and client verification.

3.5 Access MQTT Server without UTF8 Coding Check

Explains communication with MQTT server without UTF8 coding check.