Thermochrons and Hygrochrons

 

Thermochron iButtons® contain a battery and can log temperatures at regular intervals, even when not connected to a computer.  Hygrochrons log both temperature and humidity.  Each has the ability to log data all the time or only when the temperature reaches an alarm threshold.

Life Cycle: A Thermochron or Hygrochron use has a definite life cycle that follows these steps:

1) A plan is developed for the use of the device.  The plan will include the following:

    1. A description of the mission.
    2. What temperature and/or humidity ranges are required to be logged.
    3. Accuracy required. 
    4. How often the data should be logged.
    5. The length of time of the missions.
    6. What is the acceptable range for the data.
    7. If data should be logged all the time or just when the data is out of an acceptable range.

      Maxim provides an application note with more information about the mission parameters.

      2) The data logger is programmed for the mission using a special software package and a 1-Wire® adapter.

        3) The data logger is sent on the mission to collect data.

        Please note that the data logger is not waterproof.  Do not directly bury in moist soil or place in water.

        You may protect your data loggers through an iButton® Capsule, certified to "Water Resistant 3 ATM Requirements."

        4) The data logger returns from the mission and the data is retrieved.

        The same software and hardware used to program the mission is used to retrieve the data.

         

        Thermochron/Hygrochron models vary in the following ways:

          • The operating temperature range.
          • The amount of memory available for storing data.
          • The accuracy of the temperature reading.
          Please review the chart below for details on the different Thermochrons available.

          Thermochron and Hygrochron

          COMPARISON CHART

          Both measure and datalog temperature in various ranges and accuracy.

          Hygrochrons measure humidity in addition to temperature.

          Model

          		 Temperature Range Accuracy Resolution Values / Readings Logging Rate PDF Data Sheet

          DS1921G

          		 -40°C to +85°C +/- 1°C: -30°C to +70°C
          +/- 1.3°C outside this range          		 0.5°C 2048 1 to 255 min

           Data Sheet
          DS1921H +15°C to +46°C +/- 1°C 0.125°C 2048 1 to 255 min Data Sheet
          DS1921Z -5°C to +26°C +/- 1°C 0.125°C 2048 1 to 255 min Data Sheet
          DS1922E +15°C to +140°C +/- 1.5°C:  110°C to +140°C
          +/-7°C is typical from 15°C to 110°C          		 Programmable
          0.5°C - 8bit / 0.0625°C - 11 bit          		 8192 - 8 bit or 4096 - 16 bit 1 sec to 273 hrs

           Data Sheet
          DS1922L -40°C to +85°C +/- 0.5°C:  -10°C to +65°C
          (with software correction)          		 Programmable
          0.5°C - 8bit / 0.0625°C - 11 bit          		 8192 - 8 bit or 4096 - 16 bit 1 sec to 273 hrs

           Data Sheet
          DS1922T 0°C to +125°C +/- 0.5°C:  +20°C to +75°C
          (with software correction)          		 Programmable
          0.5°C - 8bit / 0.0625°C - 11 bit          		 8192 - 8 bit or 4096 - 16 bit 1 sec to 273 hrs

           Data Sheet
          DS1923 Hygrochron -20°C to +85°C Includes 0 to 100% humidity logger +/- 0.5°C:  -10°C to +65°C
          (with software correction)          		 Programmable
          0.5°C - 8bit / 0.0625°C - 11 bit          		 8192 - 8 bit or 4096 - 16 bit 1 sec to 273 hrs

          Data Sheet
          NASA is using Thermochrons for the History of Winter program.  Take a look to see some serious Thermochron use!