HIOKI U8557 – 15-Channel Module for Resistance Measurement

Key Specifications  

• 15 channels 
• Native support of thermistors up to 200 kΩ
• Real-time conversion to temperature
• 50 ms update interval 
• Resistance ranges: up to 200 kΩ, 3 ranges

Unique Advantages

• Compatible with all thermistor types up to 200 kΩ 
• Up to 15 channels at an update interval of 50 ms 

Typical Applications

• Evaluation of battery pack temperature for BMS verification and correlation 
• Evaluation of battery pack temperature during charge/discharge and degradation testing 
• Thermal evaluation of EV/HEV motors in combination with temperature (thermocouple) measurement 

Detailed Product Overview  

The U8557 Thermistor Module is a 15-channel plug-in module for the LR8450 and LR8450- 01 Data Loggers for temperature measurement using thermistors. The module measures thermistor resistance and converts it to temperature in real time, enabling direct temperature monitoring without external calculations or post-processing. 

Up to four U8557 modules can be installed in a single LR8450 or LR8450-01, enabling 60 thermistor channels with a 50 ms update interval. This configuration supports synchronized measurements in applications such as battery testing and high-channel temperature monitoring scenarios. 

Wide Thermistor Compatibility with Real-Time Conversion 

The module supports thermistors up to 200 kΩ, allowing the use of a wide range of commonly used sensor types. Thermistor coefficients can be registered directly in the logger, enabling real-time temperature calculation and display using models such as B-value or Steinhart–Hart (R-T table). This allows engineers to observe temperature changes immediately during testing and identify critical temperature behavior early. 

Integrated Multi-Signal Acquisition in a Modular Architecture 

As part of the modular LR8450 platform, the U8557 can be combined with other measurement modules for simultaneous multi-parameters acquisition. In addition to the thermistor modules, the LR8450 supports measurement of temperature with thermocouples or RTDs, DC voltage, current, strain, and CAN/CAN FD data, enabling synchronized mixedsignal measurements within a single system. This allows temperature data to be correlated with electrical or mechanical signals, simplifying analysis. The modular architecture also enables system expansion by adding modules to increase channel count or measurement types without requiring recalibration or modification of the main unit, ensuring flexibility for evolving test requirements. 

Typical applications include battery pack temperature monitoring, thermal runaway testing, and motor endurance testing, where multiple temperature points must be measured simultaneously and correlated with other signals. 

Flexible Temperature Measurement Across Multiple Sensor Types 

The LR8450 platform supports multiple temperature measurement modules, enabling users to select the appropriate sensor type based on temperature range, response time, and application requirements. 

Resistance Measurement Capabilities

In addition to temperature measurement, the U8557 Thermistor Module can also be used for multi-channel resistance measurement. It uses a 2-terminal method and supports a range from 0 to 200 kΩ across three ranges, with a resolution of 0.1 Ω. 

In contrast, the U8551 Universal Module is designed for low-resistance measurements using a 4-terminal method, with four resistance ranges up to 200 Ω and 0.5 mΩ resolution. It also supports additional measurement types such as RTD temperature measurement (e.g., Pt100, Pt1000), voltage, humidity, and 4–20 mA signals.