The SITE-LOG LRHT-1 is a compact 2-channel, battery-powered, standalone data logger designed for accurate monitoring of relative humidity and temperature.

The logger uses an internal digital humidity and temperature sensor and provides:

• 1 relative humidity channel
• 1 temperature channel
• 8 MB non-volatile flash memory
• USB and TTL-level serial communication
• Configurable alarm and excitation-control outputs
• Long-term standalone data logging

The LRHT-1 is well suited to environmental monitoring, laboratory testing, storage monitoring, HVAC applications, research, and other applications where temperature and humidity must be recorded together.

Its aluminum enclosure and conformally coated PCB provide added protection for industrial and field use. 

Relative Humidity and Temperature Measurement

The LRHT-1 simultaneously measures:

• Relative Humidity: 0–100% RH
• Temperature: −40°C to +70°C (−40°F to +158°F)

Both channels provide 12-bit measurement resolution.

Published accuracy is:

• Temperature: ±0.4°C at 25°C
• Relative Humidity: ±3% RH from 20% to 80% RH

The internal sensor design makes the LRHT-1 convenient for applications where ambient temperature and humidity are measured directly at the logger location. 

Digital Humidity and Temperature Sensor

The LRHT-1 uses a digital relative-humidity and temperature sensor for environmental measurement.

Because the sensing element is integrated into the logger, no external RH probe is required.

This makes the LRHT-1 particularly suitable for:

• Room monitoring
• Storage areas
• Laboratories
• Environmental chambers
• HVAC environments
• General ambient humidity and temperature monitoring

For applications requiring the sensor to be positioned away from the logger enclosure, the LRHT-3 provides an external 3-foot temperature and humidity probe. 

Standalone Operation and Long-Term Recording

The LRHT-1 operates independently after configuration and stores measurements in 8 MB of non-volatile flash memory.

The memory provides storage for approximately 4 million readings and retains recorded data for more than 20 years.

Logging can be configured for:

• Immediate start
• Delayed start
• Field push-button activation

When memory becomes full, the logger can either:

• Stop recording, or
• Continue recording in FIFO mode

The built-in 3.6 V lithium battery provides up to approximately 5 years of operation at a 1-minute sampling interval, depending on operating conditions and configuration. 

USB Communication and SiteView Software

The LRHT-1 connects directly to a Windows PC through its Plug & Play USB interface.

SiteView software provides tools for:

• Logger configuration
• Data download
• Real-time viewing
• Graphing
• Alarm configuration
• Custom calibration
• Custom equations
• Data analysis

The logger also includes an AUX RJ11 interface for TTL-level serial communication.

USB and AUX communication support automatic baud-rate detection from:

2400 to 115200 bps. 

Alarm and Excitation Control

The LRHT-1 provides configurable alarm and control functions for applications requiring more than basic data recording.

Each channel supports two programmable alarm thresholds.

The available output terminals can be configured for:

• Alarm output
• Excitation control

The onboard status LED provides visual indication of normal sampling, alarm conditions, and low battery status. 

Remote Access and Network Integration

Although the LRHT-1 is a USB-based data logger, it can also be accessed remotely over an Ethernet network by connecting it to a Microedge Smart-Hub.

Smart-Hub acts as a communication gateway and allows connected USB data loggers to be accessed through:

• SiteView
• SiteView-Web
• SiteView SDK
• Pluto

Smart-Hub also provides:

• RESTful Web API
• Modbus TCP Gateway

This allows LRHT-1 temperature and relative-humidity data to be integrated with third-party software, PLCs, HMIs, SCADA systems, and other industrial monitoring platforms.

Rugged Industrial Design

The LRHT-1 is housed in a durable aluminum enclosure.

The PCB is conformally coated to provide additional protection against moisture, corrosion, and mildew.

Its operating environment is:

−40°C to +70°C (−40°F to +158°F)

and:

0–95% RH, non-condensing. 

KEY FEATURES

• Relative Humidity and Temperature Measurement
  Simultaneously records RH and temperature.

• Internal Digital Sensor
  Integrated sensor eliminates the need for an external probe.

• 0–100% RH Measurement Range

• −40°C to +70°C Temperature Range

• 12-Bit Resolution
  Provides 12-bit measurement resolution for both RH and temperature channels.

• Temperature Accuracy
  ±0.4°C at 25°C.

• Relative Humidity Accuracy
  ±3% RH from 20% to 80% RH.

• 8 MB Non-Volatile Flash Memory
  Stores approximately 4 million readings.

• 1 Second to 12 Hour Sampling
  External power is required when the sampling interval is less than 5 seconds.

• Up to 5 Years Battery Life
  Based on a 1-minute sampling interval.

• USB Communication

• TTL-Level Serial Communication
  AUX RJ11 interface with automatic baud-rate detection from 2400 to 115200 bps.

• SiteView Software Support

• Programmable Alarm Thresholds

• Alarm Output and Excitation Control

• Remote Network Access through Smart-Hub

• RESTful Web API through Smart-Hub

• Modbus TCP Gateway through Smart-Hub

• Rugged Aluminum Enclosure

• Conformally Coated PCB

  
  

TYPICAL APPLICATIONS

The LRHT-1 is suitable for:

• Indoor environmental monitoring
• Laboratory monitoring
• Storage-room monitoring
• Warehouse monitoring
• HVAC monitoring
• Environmental chambers
• Research
• Product testing
• Manufacturing environments
• Museum and archive monitoring
• Building environmental monitoring
• Equipment-room monitoring
• Long-term temperature and humidity logging
• Remote environmental monitoring through Smart-Hub

DOCUMENTS

• SITE-LOG Relative Humidity Data Logger Specifications
• SiteView Specifications