S31B-MS Temperature and Humidity Mesh Node

1. Product Overview

S31B-MS is a solar-powered Dragino temperature and humidity Mesh Node. It uses an SHT31 probe to measure ambient temperature and relative humidity and sends the measurements to a Mesh gateway through a LoRa Mesh network.

The node can communicate directly with the Mesh gateway or relay data through other Mesh Nodes. It is suitable for environmental monitoring projects that require long-range coverage, have difficult site cabling, or contain locations where a direct wireless path is obstructed.

2. Applications

• Environmental monitoring for farmland, greenhouses, nurseries, and livestock facilities.
• Environmental monitoring for warehouses, cold storage, and material storage areas.
• Temperature and humidity monitoring in parks, buildings, and equipment rooms.
• Auxiliary weather monitoring and outdoor environmental data collection.
• Remote monitoring points requiring solar power and multi-hop wireless coverage.

3. Main Features

note

Payload to be added

• SHT31 digital temperature and humidity probe.
• Waterproof and anti-condensation probe protection structure suitable for long-term environmental measurement.
• Reports data after multiple samples are filtered, reducing the effect of short-term fluctuations.
• LoRa Mesh wireless communication with multi-hop relaying between nodes.
• S-type outdoor enclosure, solar panel, and 3000 mAh rechargeable lithium battery.
• Automatic periodic collection of temperature, humidity, and device status.
• The Mesh gateway displays temperature, humidity, battery, and device status in one place.
• Supports firmware upgrades through USB serial or PC BLE.

4. Enclosure and Installation Reference

For product photos, S-type enclosure dimensions, solar panel installation, and SHT31 probe position, refer to the S31B-LS version on the S31/S31B-LB/LS product page.

5. Technical Specifications

5.1 Main Unit

Item	Specification
MCU	STM32WLE5, 48 MHz ARM Cortex-M4
Flash	256 KB
RAM	64 KB
Radio	STM32WLE5 integrated sub-GHz LoRa radio
Power supply	Solar panel + 3000 mAh rechargeable lithium battery
Main board operating voltage	Approximately 2.5 V - 3.6 V
Main board operating temperature	-40 C - 85 C; battery operating temperature is subject to the battery specification
Local interfaces	3.3 V UART, BLE
Antenna	Sub-GHz LoRa antenna matching the shipping Region

5.2 SHT31 Temperature and Humidity Sensor

Item	Specification
Temperature range	-40 C - 80 C
Temperature accuracy	Typical +/-0.2 C; applicable conditions are subject to the SHT31 specification
Temperature display resolution	0.1 C
Long-term temperature drift	Less than 0.03 C/year
Humidity range	0 - 99.9 %RH
Humidity accuracy	Typical +/-2 %RH; applicable conditions are subject to the SHT31 specification
Humidity display resolution	0.1 %RH
Long-term humidity drift	Less than 0.25 %RH/year

6. Temperature and Humidity Measurement

After waking, the device obtains multiple temperature and humidity samples, filters and processes the valid samples, and then sends stable measurements to the Mesh gateway. This reduces the effect of individual reading fluctuations or brief interference on reported results.

The probe requires a short time to obtain stable data, so temperature and humidity values may not appear immediately after a manual report is triggered. If a probe reading fails, the device retries sampling. If valid data cannot be obtained continuously, the Mesh gateway displays a sensor error or indicates that no valid temperature and humidity data are available.

6.1 Factors Affecting Measurements

• Direct sunlight on the probe can cause the measured temperature to be higher than the actual air temperature.
• Mounting the probe against a wall, metal surface, or heat-generating device affects measurements.
• Condensation, water droplets, dust, and oil contamination can slow humidity response.
• Inadequate airflow may prevent readings from representing the actual surrounding environment.
• After moving from an environment with significantly different temperature or humidity, the probe requires time to stabilize.

6.2 Probe Installation Requirements

1. Install the probe where air can circulate naturally.
2. Avoid direct sunlight. If necessary, add a ventilated sun shield.
3. Do not place the probe directly against the enclosure, a wall, pipe, or other heat source.
4. Avoid condensation outlets, continuous water flow, and locations where the probe may be covered by soil.
5. Do not allow oil, paint, or chemical solvents to contact the probe protection structure.

7. Data on the Mesh Gateway

After S31B-MS is enrolled and sampling is complete, the Mesh gateway displays:

• Temperature.
• Relative humidity.
• Device battery level or battery status.
• Device online and operating status.
• Data update time.

Users do not need to perform additional configuration or parse raw data. Display names and page layout depend on the Mesh gateway version.

8. Normal Operation

After enrollment, the device automatically performs the following operations on the configured schedule:

Wake up -> Collect and process temperature and humidity -> Send to Mesh gateway -> Enter low-power sleep

To obtain data immediately, first wake the device if it is sleeping. After the device is active, hold the button and release it within 1 to 3 seconds. The device then collects and sends one temperature and humidity report.

9. Quick Start

9.1 Installation

1. Confirm that the product label shows S31B-MS and that the device and antenna Region are suitable for the deployment location.
2. Install the LoRa antenna before powering on the device.
3. Install the solar panel in a location with stable, unobstructed sunlight.
4. Install the temperature and humidity probe according to Section 6.2.
5. Keep the antenna away from large metal surfaces, high-power electrical equipment, and enclosed metal boxes.

9.2 Initial Enrollment

For complete instructions, see Quick start — 2. First network test.

10. Power Consumption and Solar Power

Actual battery life depends on:

• Automatic wake-up and temperature/humidity reporting interval.
• Mesh network coverage and number of relay hops.
• Solar panel orientation, sunlight, obstruction, and dust accumulation.
• Ambient temperature and battery condition.

Shortening the reporting interval or keeping the device awake for long periods increases power consumption. Evaluate the deployment using the worst seasonal sunlight conditions at the site and clean the solar panel regularly. If the battery level continues to fall, first check sunlight, obstructions, and the solar panel connection.

11. Use and Maintenance

• Regularly remove dust, leaves, and other obstructions from the solar panel.
• Regularly inspect the antenna, waterproof connectors, cables, and enclosure mounting.
• Keep the temperature and humidity probe protection structure clean and ventilated. Do not clean the probe directly with a high-pressure water jet.
• After prolonged exposure to high humidity, condensation, or contamination, check whether the probe response and readings return to normal.
• For projects requiring high measurement consistency, compare the device against a reference instrument according to the project maintenance schedule.

12. Troubleshooting

Issue	Solution
The Mesh gateway cannot find the device	Confirm that the gateway and device use the same Region, check that the antenna is installed, and hold the button for about 1 second to wake the device
The device is enrolled but no temperature or humidity data are shown	While the device is active, hold the button and release it within 1 to 3 seconds, then wait briefly. If no data appear, check the probe and firmware model
Data do not appear immediately after a manual report	The device is collecting and processing temperature and humidity data; wait for the current sampling cycle to finish
The temperature remains too high	Check whether the probe is exposed to direct sunlight, close to a heat source, against a wall, or installed in a poorly ventilated location
Humidity response is slow	Check whether the probe protection structure is covered by water droplets, condensation, dust, or contaminants
Temperature or humidity readings are clearly abnormal	Move the device to a ventilated location with stable conditions and check whether the probe is contaminated or damaged
The battery level continues to fall	Check solar panel orientation, obstruction, dust, cable connections, and ambient temperature
The device frequently goes offline	Check the antenna, installation position, site obstructions, Mesh gateway status, and battery level
Temperature and humidity disappear after an upgrade	Confirm that the firmware matches the S31B-MS model and shipping Region