We needed a CAN-bus connected 16-channel temperature sensing interface for a circuit-board functional test application. Specifically to monitor the MOSFET temperatures in the flyback converters of the OGS battery board with active balancers. Not finding such interface, we started designing a quick design to perform this task. This escalated quickly to a real product design; this CANopen® interface for 16 thermistors.

Note that this device is not particularly intended for high-accuracy applications, mostly because that does not fit the capabilities of low cost NTC thermistor sensors. Instead, the device enables expanding temperature monitoring using low-cost sensors. For example to monitor motors, bearings, cooling systems, etc.

Functionality
Measure 16 standard NTC thermistors (typically 10kΩ)
Sample rate 100Hz down to 1/60Hz
CANopen® fieldbus, generic I/O module profile CiA 401
Modbus RS485 fieldbus
Configuration via CANopen or using PC application via micro-USB port
Possibility for custom firmware with specific signal processing functions

24-Bit delta-sigma analog digital converter
Autoranging excitation source 10µA-1mA, max 3.3V
OLED display shows all 16 temperature readings (°C or °F)
Sensor inputs galvanically isolated from CAN-bus (not from each other)
CANopen® device profile for generic I/O modules (CiA 401)
Supports LSS node-ID assignment and Fastscan (CiA 305)
Supports automatic bit-rate detection between 10kbps and 1Mbps (CiA 801)

Type : NTC