GSM MONITORING ACTIVE

Temperature &
Humidity Data Logger

Remote temperature and humidity monitoring with SMS and call alerts. The THDL-GSM-WiFi uses a high-accuracy SHT40 sensor, shows live readings on an OLED display and triggers an external hooter through a relay output.

SHT40 SensorSMS & Call AlertsUp to 6 Mobile NumbersRelay for HooterWiFi Setup

View specifications

GSM Temperature and Humidity Data Logger THDL-GSM-WiFi

Nex-G Automation LLP

−40 to +125°CTemperature Range

0–100% RHHumidity Range

±0.2°CTemperature Accuracy

Up to 6Alert Mobile Numbers

9–24V DCPower Supply

Temperature humidity monitoring system

Remote monitoring for critical storage environments.

The THDL-GSM-WiFi is a compact temperature and humidity data logger for remote monitoring in industrial and critical storage environments. It combines a digital SHT40 sensor probe, an OLED display, GSM-based SMS and call alerts and a relay trigger, and is configured over WiFi rather than a keypad.

Temperature high-low alarmHumidity SMS alertAlerts up to 6 numbersSensor failure alertHooter relay outputNo keypad, tamper resistant

Industrial Temperature and Humidity Data Logger

Alert-driven monitoring

Know the moment temperature or humidity goes out of range.

When a reading crosses your set limits, the logger sends an SMS and places a call to up to six numbers and can switch a hooter or siren through its relay output.

Sensor7Semi SHT40 digital probe

Display0.9-inch OLED

AlertsSMS and call via GSM

Relay1x NO/NC, max 2A

SetupWiFi access point

Power9V to 24V DC

System control

How the GSM temperature logger works.

The sensor measures, the logger compares readings with your thresholds and alerts by SMS, call and relay when a limit is crossed.

01	Sensing	The SHT40 digital sensor probe measures temperature and relative humidity.
02	Display	The 0.9-inch OLED shows real-time readings at the device.
03	Threshold Check	Readings are compared against the temperature and humidity limits you configure.
04	SMS & Call Alerts	The 4G GSM module sends SMS and call alerts to the configured mobile numbers.
05	Relay Output	The relay triggers an external hooter or siren on a threshold breach.

Alert flow

From out-of-range reading to action on site.

The same event reaches people by phone and alerts staff locally through the hooter.

Reading crosses limit

Temperature or humidity goes above or below the set threshold.

→

Logger detects

The device compares the SHT40 reading with your settings.

→

Alerts are sent

SMS and call go to configured numbers, and the relay can sound a hooter.

→

Team responds

Staff check the storage area and correct the condition.

Alert modes

Built around threshold alarms and failure detection.

01 · SMS AlertText message with temperature, humidity and location when a threshold is crossed.

02 · Call AlertVoice call to configured numbers so a breach is not missed.

03 · Sensor Failure AlertAlert when the sensor is open or fails, so a dead probe is not mistaken for normal readings.

04 · Hooter RelayRelay output to trigger an external hooter or siren on a breach.

Why choose it

Key capabilities

Purpose-built for unattended storage rooms, cold chain and critical environments.

High-Accuracy SHT40 Sensing

7Semi SHT40 digital probe with ±0.2°C temperature and ±2% RH accuracy, over −40°C to +125°C and 0–100% RH.

GSM SMS and Call Alerts

4G GSM module sends SMS and call alerts without needing internet or WiFi at the site.

Alerts to Six Numbers

Configure up to 6 mobile numbers so several people are notified of a breach.

WiFi Configuration, No Keypad

Set thresholds, numbers and calibration through a WiFi access point and web interface. No keypad means settings cannot be changed locally.

Relay Output for Hooter

1x NO/NC contact, up to 2A, to drive an external hooter or siren.

Strategic System Values

Core System Advantages

Works Without Site Internet

GSM alerts do not depend on the site network.

Tamper-Resistant Design

No keypad, so settings are changed only through WiFi configuration.

Multiple User Alerts

Up to six numbers receive alerts for a breach.

Local and Remote Warning

Phone alerts plus an on-site hooter through the relay.

Technical specifications

Engineering details

THDL-GSM-WiFi

Sensor	7Semi SHT40 digital probe	Temperature and humidity
Temperature Range	−40°C to +125°C	Specified range
Humidity Range	0% RH to 100% RH	Specified range
Accuracy	±0.2°C, ±2% RH	Temperature, humidity
Display	0.9-inch OLED	Real-time readings
Connectivity	GSM (4G) + WiFi	GSM for alerts, WiFi for setup
Configuration	WiFi access point / web interface	Thresholds, numbers, calibration
Alert Numbers	Up to 6 mobile numbers	SMS and call
Relay Output	1x NO/NC contact	Max 2A load
Power Supply	9V to 24V DC	Specified input

Typical applications

Where it gets deployed

01❄️ Cold Chain & Cold Storage Monitoring

02🏭 Warehouse & Storage Rooms

03🧪 Clean Rooms & Laboratories

04🌱 Agriculture & Greenhouses

05💊 Pharma & Vaccine Storage

06🍽️ Food Processing & Storage

Control Ecosystem

WiFi Configuration Capabilities

Threshold SettingsSet high and low limits for temperature and humidity.

CalibrationAdjust calibration values to match a reference instrument.

Alert NumbersStore up to 6 mobile numbers for SMS and call alerts.

WiFi Access PointConnect a phone or laptop to the device to open the web interface.

Frequently Asked Questions

GSM Temperature & Humidity Data Logger FAQ

It measures temperature (−40°C to +125°C) and relative humidity (0% to 100% RH) using a 7Semi SHT40 digital sensor probe.

The specification lists ±0.2°C for temperature and ±2% RH for humidity.

A 4G GSM module sends SMS and call alerts when a threshold is crossed. A SIM card with network coverage at the site is required.

Up to 6 mobile numbers can be configured.

Yes. A relay output (1x NO/NC contact, max 2A) can drive an external hooter or siren on a threshold breach.

Through a WiFi access point and web interface. You set thresholds, mobile numbers and calibration. There is no keypad.

The device sends a sensor open/failure alert.

9V to 24V DC.

Temperature &Humidity Data Logger