This page:
Q1: What is the Thermochron iButton?
The Thermochron is a single-chip digital thermometer, thermostat, clock, calendar
and data logging memory housed in the stainless steel iButton. Battery-powered
and physically able to endure the most challenging environments, the Thermochron
is ideal for data logging missions in the -40°C to 85°C temperature
range.
Q2: Where would I use a Thermochron iButton?
You can use the Thermochron anywhere you want to monitor temperatures from -40C
to 85C. Extremely durable and only 16mm in diameter, the Thermochron is ideally
suited for remote and/or mobile thermal tracking in refrigeration units, trucks,
crates, and incubators for purposes of chemical, food or other organic material
storage, maintenance and transportation. It can stick to bottles, such as thermally
sensitive chemicals, or mount on walls. For waterproofing applications, see
the DS9107 iButton Capsule.
DS9107 Data Sheet
(opens new tab or window)
Q3: What's the life span of the Thermochron?
The Thermochron lifespan is dependent upon usage conditions, specifically, how
often the device samples, what environmental conditions (temperature) to which
the iButton is exposed, etc. See the lifetime/lifespan graphs located in the
Thermochron datasheets for lifetime expectancies based on usage conditions.
Q4: What configuration can I use to string Thermochrons together and what
cable length can I use?
Please see Application Note 148.
App.
Note 148 Guidelines (opens new tab or window)
Q5: Are there alternatives to the Blue Dot Receptor for I/O with the Thermochron?
You can multi-drop the Thermochron just like other iButtons and 1-Wire devices.
Other probes besides the Blue Dots can be found on the following pages.
Q6: How do you know when the lithium is low or nearly exhausted?
You can check the register that records the total number of conversions over
the lifetime of the Thermochron. This register serves as a "gas gauge"
because the primary consumer of lithium power is the conversion circuitry. By
the way, the conversion process uses lithium even if the chip's other "front
end" functions are externally powered.
See the lifetime graphs at the end of the DS1921G datasheet.
DS1921G-F5
Datasheet (opens new tab or window)
Q7: What does 'water-resistant' mean for the Thermochron?
Thermochron iButtons have a grommet that creates a seal that is water-resistant
but not waterproof (hermetic). They are IP56 rated (see below for link to more
information). If you are using the iButton in an environment that exposes the
iButton to high moisture content or is simply splashed with fresh or salt water,
there should be no problem. Just wipe it off before touching it to the Blue
Dot. If you have the need to submerge the iButton then we suggest that you use
our DS9107 capsule to keep them dry while logging temperatures.
Some of our partners have other waterproof solutions for our Thermochrons.
Click on the link below to see their products.
DS9107
iButton Capsule (pdf file, opens in new tab or window)
Q8: What are the true temperature limits of Thermochrons?
Temperature ranges for all data loggers can be found in the table on this page.
Operating any logger above or below its thermal operating range can damage its internal battery or components.
If the logger records data while in an environment above or below its thermal operating range, the recorded data collected will not go above or below the specified operating range. The logger will continue to operate at temperatures above or below its operating range for an unspecified time before stopping due to lack of battery power. Depending on the length of time that the logger is exposed to temperatures outside of its operating range, the logger may continue operating properly.
Storage or operation above 50C significantly reduces battery life.
See each loggers datasheet for expected life span at different temperatures.
Q9: Where do I get software for the Thermochron?
Esis Pty Ltd
Q10: Where can I find code for a Linux port for the Thermochron?
It can be found in our 1-Wire Public Domain Kit.
1-Wire Public
Domain Kit
Q11: Is there a Java container class for the Thermochron?
Yes. The DS1921 family of Thermochrons are supported by the Java "container"
OneWireContainer21. The DS1922 family of Thermochrons, along with the DS1923 Hygrochron
are supported by OneWireContainer41. They are both available for download in the
1-Wire API for Java Software Development Kit (SDK).
1-Wire API for Java
SDK
Q12: How do I turn off the Thermochron?
You can stop
the current mission from taking samples with a command under "Options"
in the iButton Viewer (1-Wire for Windows TMEX). Also, the 1-Wire API for Java
supports turning off the clock oscillator but no demos currently expose this feature.
Q13: How do I export the data from the OneWireViewer to Excel?
There is an Application Note that describes how to export the data from
Thermochrons into an Excel spread sheet. The Application Note is App Note 3809
Exporting DS192x Logger Data from the OneWireViewer into Excel.
We also
have several partners with software products that will automatically download
Thermochron data into an Excel spread sheet.
Partner Software Products
Q14: Is there a Starter Kit for the DS1923 Humidity iButton?
There is not a starter kit just for the DS1923. While the Thermochron Starter
Kit, DS1921K, does not contain a DS1923, the kit can be used with any iButton.
The kit does have a USB Port adapter, a "Blue Dot" cable, and a DS1921G
Thermochron. The kit also contains the instructions as to where free evaluation
software can be downloaded.
Q15: How long is the Thermochron good
for (battery life)?
There are charts in the data sheets that show
battery life. Battery life is effected by temperature and the rate of sampling.
The higher the temperature or the quicker the sample rate, the shorter the battery
life.
Q16: I've been using the DS1921. Now I want to use the new DS1922,
can I use the same hardware?
Yes, the hardware used with the DS1921
can be used with all types of the DS1922 and DS1923.
Q17: The iButton
Viewer won't recognize the DS1922 or DS1923. What is the problem?
The
iButton Viewer was retired and replaced by the OneWireViewer before the DS1922/23
data loggers were introduced. The OneWireViewer is also free for the download.
OneWireViewer Software
Q18: Why won't the OneWireViewer start
my Thermochron missions?
The answer is to fill in the Temperature
Alarm points. Even if the alarm is not turned on, the alarm points must have a
value filled in.
Q19: The Temperature tab at the top of the OneWireViewer
doesn't show the temperature like before?
The Temperature tab is
used in the Forced Conversion mode. This cannot be done when there is a mission
in progress. Go to the Mission tab and use the lower Temperature tab to see the
data from the Thermochron.
Q20: Is it possible to use the Thermochrons
to measure the internal temperature of large mammals?
Maxim does
not recommend using the Thermochrons inside any living creature.
Q21:
Do I need to calibrate Thermochrons and Hygrochrons?
Maxim stands
by our data sheets specifications for all parts we make.
Thermochron:
Our temperature data loggers measure temperature by using an Integrated Circuit (IC) which does not change significantly over time. They are calibrated at the wafer level during manufacturing at the factory. They are also tested after packaging and again at final test to insure their calibration and accuracy. Since we use our IC for temperature measurement, and not a traditional thermistor, we leave the decision to recalibrate up to the end user. Since the cost of recalibration may be more than the original cost of the logger itself, we feel our loggers are the most cost effective data loggers on the market.
Hygrochron:
Our humidity logger measures %RH using a standard humidity sensor. Therefore, it will need to be recalibrated periodically depending on the environment it is operating in since absorption of contaminants can degrade its accuracy.
If
you decide that you need to have your data loggers recalibrated or if you need
an official letter of NIST calibration for your loggers then we have several partners
that can provide these services for you. All partners that provide these services
can be found in our online Solutions Search at the link below.