MQTT is an IoT transport protocol developed by IBM. It is designed for lightweight publish/subscribe message transmission and aims to provide reliable network services for IoT devices in low-bandwidth and unstable network environments. . Its core design ideas are open source, reliable, lightweight and simple, and has the following main features:
1. Very small communication overhead (minimum message size is 2 bytes);
2. An easy-to-use client that supports various popular programming languages (including C, Java, Python, Ruby, etc.);
3. Support release/reservation model to simplify application development;
4. Provide three different message delivery levels, allowing messages to reach their destinations on demand, adapting to network transmission needs that work in unstable environments.
Due to the technical advantages of MQTT itself, more and more companies choose MQTT as the standard protocol for IoT product communication. The wireless transmission modules of the Zongheng Intelligent Control 4G series also support the MQTT protocol, and of course can be adapted according to customer needs.
Wireless transmission module selection table
| model | Interface Type | Tipo de red |
| ZHC492C | 1RS485, 4DI, 4DO, 4AI | 4G full network communication |
| ZHC493C | 1RS485, 2DI, 1DO, 1AI | 4G full network communication |
| ZHC495C | 1RS485, 8DI, 8DO | 4G full network communication |
| ZHC466C | 1RS485, 4AI, 4AO | 4G full network communication |
Wireless transmission module application cases
The remote automatic water supply monitoring system mainly monitors the water level of the water tower. This solution uses two wireless transmission modules to configure the networking function. The remote wireless transmission module AI is connected to the water level sensor to monitor the water level of the water tower in real time. The near-end wireless transmission module is connected to the PLC. Use the PLC to issue commands to read the AI value of the remote device (that is, the water level of the water tower measured by the water level sensor). This solution uses the point-to-point/one-to-many transmission function of the wireless transmission module, which can monitor data from multiple water towers.