DS1921L-F5X

The DS1921 Thermochron iButton is an ideal device to monitor the temperature of any object it is attached to or shipped with, such as perishable goods or containers of temperature sensitive chemicals. Using TMEX, the read/write nonvolatile memory can store an electronic copy of shipping information, date of manufacture and other important data written as clear as well as encrypted files. The unique registration number and a non-resettable counter that increments with each new mission provide traceability and evidence in case of tampering with the device.

The DS1921L-F5X Thermochron iButtons are rugged, self-sufficient systems that, once setup for a mission, measure temperature and record the result in a protected memory section. The recording of DS1921L-F5X is done at a user-defined rate, both as a direct storage of temperature values at incrementing memory addresses as well as in the form of a histogram. Up to 2048 temperature values taken at equidistant intervals ranging from 1 to 255 minutes can be stored. The histogram provides 63 data bins for a resolution of 2°C. Each bin of DS1921L-F5X is implemented as a 16-bit binary counter that is incremented if the value of a temperature measurement falls into the range of the bin. If the temperature leaves a user-programmable range, the DS1921 will also record when this happened, for how long the temperature stayed outside the permitted range, and if the temperature was too high or too low. A total of 24 such events can be recorded, 12 for exceeding each temperature limit. Additional read/write non-volatile memory independent of the memory used for temperature logging offers a simple solution to storing and retrieving information pertaining to the object to which the DS1921 is associated. Data is transferred serially via the 1-Wire protocol, which requires only a single data lead and a ground return and which allows the device to be accessed with minimal hardware.

The DS1921L-F5X scratchpad is an additional memory area that acts as a buffer when writing to the read/write memory and to the special function registers required to mission the device. Data is first written to the scratchpad where it can be read back. After the data has been verified, a Copy Scratchpad command will transfer the data to memory. This process ensures data integrity when modifying the memory. A 48-bit serial number is factory-lasered into each DS1921 to provide a guaranteed unique identity which allows for absolute traceability. The durable MicroCan package is highly resistant to environmental hazards such as dirt, moisture, and shock. Its compact, coin-shaped profile is self-aligning with mating receptacles, allowing the DS1921 to be easily used by human operators. Accessories permit the DS1921 to be mounted on almost any surface, including containers, pallets and bags.