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:
- A description of the mission.
- What temperature and/or humidity ranges are required to be logged.
- Accuracy required.
- How often the data should be logged.
- The length of time of the missions.
- What is the acceptable range for the data.
- 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.
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We recommend our ExactLog software, paired with the LinkUSBi Touch and Hold Reader.
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."
- Read this application note for information.
4) The data logger returns from the mission and the data is retrieved.
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.
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 | Datasheet |
|---|---|---|---|---|---|---|
| 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 | Datasheet |
| DS1921H | +15°C to +46°C | +/- 1°C | 0.125°C | 2048 | 1 to 255 min | Datasheet |
| DS1921Z | -5°C to +26°C | +/- 1°C | 0.125°C | 2048 | 1 to 255 min | Datasheet |
| DS1922E | +15°C to +140°C | +/- 1.5°C: 110°C to +140°C +/-7°C typical from 15°C to 110°C |
Programmable 0.5°C (8-bit) / 0.0625°C (11-bit) |
8192 (8-bit) or 4096 (16-bit) | 1 sec to 273 hrs | Datasheet |
| DS1922L | -40°C to +85°C | +/- 0.5°C: -10°C to +65°C (with software correction) |
Programmable 0.5°C (8-bit) / 0.0625°C (11-bit) |
8192 (8-bit) or 4096 (16-bit) | 1 sec to 273 hrs | Datasheet |
| DS1922T | 0°C to +125°C | +/- 0.5°C: +20°C to +75°C (with software correction) |
Programmable 0.5°C (8-bit) / 0.0625°C (11-bit) |
8192 (8-bit) or 4096 (16-bit) | 1 sec to 273 hrs | Datasheet |
| DS1925L | -40°C to +85°C | +/- 0.5°C: -40°C to +85°C (with software correction) |
Programmable 0.5°C (8-bit) / 0.0625°C (11-bit) |
122K (8-bit) or 61K (16-bit) | 3 min to 273 hrs | Datasheet |
| DS1923 Hygrochron | -20°C to +85°C Humidity: 0–100% |
+/- 0.5°C: -10°C to +65°C (with software correction) |
Programmable 0.5°C (8-bit) / 0.0625°C (11-bit) |
8192 (8-bit) or 4096 (16-bit) | 1 sec to 273 hrs | Datasheet |
Tap a spec to compare all models side by side:
| Model |
|---|
+/- 1.3°C outside this range
+/-7°C typical from 15°C to 110°C
0.5°C (8-bit) / 0.0625°C (11-bit)
(with software correction)
0.5°C (8-bit) / 0.0625°C (11-bit)
(with software correction)
0.5°C (8-bit) / 0.0625°C (11-bit)
(with software correction)
0.5°C (8-bit) / 0.0625°C (11-bit)
Humidity: 0–100%
(with software correction)
0.5°C (8-bit) / 0.0625°C (11-bit)
