| Brochure | Brochure 2 | DS1921G | DS1922L - DS1922T | DS1923 |

testo 174   Monitor storage temperatures - Small and practical
-  Accurate, puntual temperature logging with up to 3900 readings
- Alarm display if user-defined maximum / minimum values are exceeded
- Software to read out data, data analysis and parameter setting ( optional )
- Secure data even if battery is spent
- Measure range  -30 to  +70°C
- Protection class IP65


Temperature Data Loggers
The Thermochron® family of iButtons are globally addressable, dedicated trackers that can go wherever thermally vulnerable products go, monitoring time and temperature and storing the data. The data can then be easily uploaded and analyzed to detect possible thermal damage.  

There are several Thermochrons from which to choose. The  DS1921G, DS1921H, and the DS1921Z represent our standard Thermochrons, and the DS1922L (new), DS1922T , and the 1-Wire chip DS2422 (new) represent our high-capacity Thermochrons with more logging memory, increased accuracy, and increased resolution.

The iButton’s embedded computer chip integrates a 1-Wire transmitter/receiver, a globally unique address, a thermometer, a clock/calendar, a thermal history log, and 512 bytes of additional memory to store user data (such as a shipping manifest). The recyclable iButton logs data for more than 10 years. 

Digital Hygrometer   <-NEW  

Our Hygrochron™ family of iButtons ( DS1923 ) adds an embedded humidity sensor to the temperature-logging capability of the high-capacity Thermochron family to create a data logger that records both temperature and humidity. With these two pieces of data, relative humidity can be logged as a function of time. The tiny opening in the lid of the Hygrochron iButton employs a special filter that allows water vapor to pass through and reach the internal humidity sensor, but repels liquid-phase water (see picture).

For applications where both temperature and humidity are important (foods, chemicals, powders, HVAC systems), the Hygrochrons deliver unprecedented performance in an unbelievably compact size.


Rugged iButtons Attach to Almost Anything
The 16mm iButtons (about the size of 5 stacked dimes) attach unobtrusively to almost any container surface or wall-on bottles, totes, boxes, crates, pallets, air cargo containers, refrigerators, semi trailers, railroad freight cars, etc. The iButton’s stainless steel armor withstands dirt, moisture and rough treatment. 

Versatile Data Storage: Log and Histogram Formats
Thermochron and Hygrochron iButtons can wake up to take time-stamped temperature and/or humidity readings at equal time intervals, then store them in a log format in on-board "datalog" memory. The standard Thermochrons (DS1921G/H/Z) allow 2048 readings with time intervals of 1 to 255 minutes, while the high-capacity Thermochrons/Hygrochrons allow 8192 readings with time intervals from 1 second to 273 hours. Additionally, the Hygrochron allows for simultaneous temperature and humidity logging and offers selectable resolution settings.

The way in which the iButtons log data can be setup by the user prior to use. This is called "missioning". Typically, during missioning the user chooses the time to begin temperature/humidity readings, sets a sampling rate, sets high and low alarm thresholds, and determines whether to rollover when the readings fill up the datalog memory or to simply stop logging. This method of data storage records when a critical thermal/humidity exposure occurs and helps to assign accountability for any resulting loss of product quality.
Standard Thermochrons, the DS1921G, H, and Z also simultaneously store each temperature sample in a histogram. The histogram memory consists of 63 bins in 2-degree increments for the DS1921G or 64 bins in 0.5-degree increments for the DS1921H or Z. Each bin holds 65,500 temperature readings for up to 10 years. The histogram method of data storage is perfect for applications with a need for long-term monitoring but with less-strict accuracy requirements. The higher capacity Thermochron and Hygrochron lines do not have the histogram function, but they have nearly 4 times the data logging memory.

Thermochron Family of Products
Our standard Thermochron, the DS1921G, logs temperatures over a wide temperature range of -40 °C to 85°C. The H and Z Thermochrons are our high-resolution versions. The DS1921H is designed for the human temperature range while the DS1921Z is designed for applications that need high resolution around 0°C.
The high capacity Thermochrons are the DS1922L, DS1922T, and the DS2422. The DS1922L is the standard high capacity Thermochron iButton that logs temperatures over the range of -40°C to 85°C. It has an 8192 byte temperature log with accuracy correctible (by software) to ±0.5°C from -10°C to +65°C. It has selectable 8-bit (0.5°C) or 11-bit (0.0625°C) resolution. The temperature log values are also selectable (between 8-bit or 16-bit ). The DS1922T Thermochron iButton is similar to the DS1922L only with a higher temperature logging range (that can be used in manufacturing processes involving sterilization techniques). The main differences between the two is that its temperature range is 0°C to 125°C, and it’s accuracy is software-correctible to ±0.5°C from 20°C to +75°C.
Finally, the DS2422 operates the same way (through a 1-Wire interface), and with the same functionality as the DS1922L. However, it is a packaged ic (24-lead, 300-mil SO) that when connected to an optional analog-to-digital converter (ADC) and a charge pump, application-specific dataloggers can be built (i.e., humidity, pressure, light sensor, material stress, etc).

Product Temperature Range Humidity Range Temperature Accuracy* Temperature Resolution Humidity Resolution Data Log
DS1921G -40°C to 85°C  N/A ±1°C 0.5°C N/A 2048
DS1921H 15°C to 46°C N/A ±1°C 0.125°C N/A 2048
DS1921Z -5°C to 26°C N/A ±1°C 0.125°C N/A 2048
DS1922L -40°C to 85°C N/A ±0.5°C
Software Correction
N/A 8192
DS1922T 0°C to 125°C N/A ±0.5°C (SC) 0.5°C
N/A 8192
DS2422 -40°C to 85°C N/A ±0.5°C (SC) 0.5°C
N/A 8192
DS1923 -20°C to 85°C 0 to 100%
±0.5°C (SC) 0.5°C

*Temperature accuracy denoted in this table is effective over most of the temperature range of the part. For full-range accuracy, please refer to the part’s datasheet.

Missioning the Thermochron
Missioning the Thermochron or Hygrochron iButton is done with a PC or handheld. The iButton connects to a Blue Dot receptor (a low cost reader interface) which in turn is connected to a  1- Wire Adapter attached to a computer. This site provides free evaluation software to set start time, sampling rate, and alarm thresholds.
The low cost reader interface includes: 
           DS9490R -  1-Wire to USB Adapte


How to Download Free Evaluation Software
Two different evaluation software programs are available to be downloaded. They can be downloaded here. Both programs depend upon the 1-Wire Drivers installation package. Version 3.21 of the 1-Wire Drivers (also known as the TMEX Runtime Environment—RTE) includes the iButton Viewer. It supports the DS1921G, H, and Z. Version 4.00 of the 1-Wire drivers includes a link to download and install the One Wire Viewer. It is a Java program that contains support for both Thermochrons and Hygrochrons. The software, of course, depends upon the correct hardware being installed on a PC. To do this, plug the 1-Wire adapter into the PC, connect the Blue Dot Receptor to the adapter, and plug in a Thermochron or Hygrochron in the Blue Dot. Then, run one of the above-mentioned programs to locate and click on the iButton’s serial number. This starts the program/mission wizard. It is a guide that provides the steps to set up a temperature/humidity logging mission.

Briefly, the steps include:

  1. Set the clock.
  2. Set the time alarm.
  3. Set the sample rate.
  4. Set the temperature/humidity alarm.
  5. Set the mission start delay.
  6. Check when mission will end; select data rollover or not.
  7. Finish.

The kit includes:

Thermochron FAQ
Visit the Thermochron FAQ section.