The HCF100 is controlled by a microprocessor. This conducts both self diagnostics and automatically calibrates the sensor when ambient conditions vary, thus avoiding false alarms. A hand-held datalogger can be connected to the HCF100 and information about the sensor can be read and printed out i. e. : the serial number the sensor condition how many times the sensor has been powered up how many alarms have occurred date of manufacture present temperature of the device the preset calibration state.