How To Use A Multi-Point Temperature Acquisition Unit

Working Principle and Application in Grain Monitoring

In grain storage, industrial warehousing, and environmental monitoring, temperature is always one of the most critical indicators. Especially in grain storage, temperature is often considered the "first signal" of grain condition changes. Traditional manual temperature measurement is not only inefficient, but also unable to accurately reflect the internal condition of bulk materials.

With the development of modern storage systems, multi-point temperature acquisition units have become a core component in grain monitoring systems. This article explains how these devices work, how to use them, and how they are applied in real-world scenarios.

A multi-point temperature acquisition unit is an industrial device designed to collect temperature data from multiple sensors and transmit it to a monitoring system. Instead of measuring temperature directly, it connects to temperature cables or probes distributed across different positions and gathers all data into a centralized system.

In grain storage applications, sensors are typically arranged at different depths and locations within the grain bulk. By collecting data from multiple points, the system provides a complete picture of temperature distribution, which is far more meaningful than a single measurement.

For example, devices such as the ZS-RTU-800P and ZS-RTU-1600P developed by Langfang Zhaosui support hundreds to thousands of sensing points, with long-distance transmission and strong anti-interference capability, making them suitable for large-scale grain storage environments.

ZS-RTU-800P

ZS-RTU-1600P

Temperature sensing cables are first installed inside the grain storage structure, typically arranged in a vertical suspended layout from the top of the silo down to the bottom. This configuration ensures that temperature data can be collected at multiple depths within the grain bulk, allowing accurate detection of temperature gradients and potential hotspots.

Depending on the size and type of the storage facility (flat warehouse, steel silo, or concrete silo), multiple cables are evenly distributed across the storage area to achieve full coverage.

After physical installation, the cables are connected to the data acquisition unit through designated input channels. In systems based on a single-bus communication protocol (such as DS18B20), multiple sensors share a single communication line.

Each sensor on the bus is assigned a unique digital address, allowing the acquisition unit to identify and read data from each sensor individually.

Important considerations:

• Each sensor must have a unique ID address to avoid communication conflicts
• Wiring connections must be correct, stable, and well-insulated
• Long-distance transmission requires proper signal integrity design (e.g., shielding, termination, and power stability)
• Cable routing should avoid strong electromagnetic interference sources

The data acquisition unit is typically powered by an industrial-grade DC power supply, supporting a wide voltage range such as 9–36V DC, which ensures stable operation under varying field conditions.

The device is usually installed inside an electrical control cabinet and mounted using a standard DIN rail structure, which simplifies installation and maintenance.

After power is applied:

• The device automatically performs internal initialization
• Communication interfaces are activated
• Sensor scanning begins without requiring complex manual setup

This plug-and-play design significantly reduces deployment time and technical complexity.

To enable communication between the acquisition unit and the monitoring system, several basic parameters must be configured according to project requirements:

Serial communication parameters:

• Device address (Modbus ID)
• Baud rate (e.g., 9600 / 19200 / 115200)
• Data format (commonly 8N1)

For network-enabled devices, additional parameters include:

• IP address
• Subnet mask
• Gateway
• Communication port

These settings ensure compatibility with various industrial systems such as PLCs, SCADA platforms, and upper-level management software.

The acquisition unit operates using a polling mechanism to continuously read data from all connected sensors.

Instead of reading all sensors simultaneously, the system processes them in sequence at high speed:

• Read temperature from the first sensor
• Store the collected data internally
• Switch to the next sensor
• Repeat the process until all sensors are read

After completing one full scan cycle, the system immediately starts the next cycle, ensuring continuous monitoring.

Although the data is collected sequentially, the scanning speed is fast enough to provide a near real-time representation of the temperature distribution within the storage structure.

This method also improves communication stability and reduces bus conflicts in multi-point systems.

Once the data is collected, it is transmitted to the monitoring system through various communication interfaces.

Common transmission methods include:

• Integration with PLC or SCADA systems via Modbus RTU / Modbus TCP
• Direct connection to PC-based monitoring software
• Remote transmission via IoT gateways or 4G modules to cloud platforms

On the monitoring interface, users can access:

• Real-time temperature values at each sensor point
• Historical data trends and curves
• Temperature distribution maps inside the grain bulk

These visualization tools allow users to quickly identify abnormal temperature changes, enabling timely intervention such as ventilation, grain turning, or inspection.

In a complete grain monitoring system, the workflow can be summarized as:

Temperature Cable → Acquisition Unit → Communication Network → Monitoring Platform (PC/Mobile)

This structure enables:

• Continuous unattended monitoring
• Remote access from computers or mobile devices
• Early detection of potential risks (heating, moisture, spoilage)

Ultimately, it helps improve grain storage safety, reduce losses, and enhance management efficiency.

A typical grain storage facility is configured as follows:

• 6 temperature cables installed inside the silo
• 20 sensing points on each cable

This results in a total of:120 monitoring points distributed throughout the grain bulk

System Operation

The acquisition unit continuously scans all connected sensors and updates the monitoring system in real time.

What Operators Can See

Based on the collected data, operators can remotely access the system via computer or mobile devices to:

• Detect localized temperature rise (hot spots)
• Monitor overall temperature trends within the grain
• Evaluate ventilation effectiveness
• Prevent spoilage and mold growth