iButton FAQs

Thermochron

What is the Thermochron iButton?
Where would I use a Thermochron iButton?
What's the life span of the Thermochron?
What configuration can I use to string Thermochrons together and what cable length can I use?
Are there alternatives to the Blue Dot Receptor for I/O with the Thermochron?
How do you know when the lithium is low or nearly exhausted?
What does 'water-resistant' mean for the Thermochron?
What are the true temperature limits of Thermochrons?
Where do I get software for the Thermochron?
Where can I find code for a Linux port for the Thermochron?
Is there a Java container class for the Thermochron?
How do I turn off the Thermochron?
How do I export the data from the OneWireViewer to Excel?
Is there a Starter Kit for the DS1923 Humidity iButton?
How long is the Thermochron good for (battery life)?
I've been using the DS1921. Now I want to use the new DS1922, can I use the same hardware?
The iButton Viewer won't recognize the DS1922 or DS1923. What is the problem?
Why won't the OneWireViewer start my Thermochron missions?
The Temperature tab at the top of the OneWireViewer doesn't show the temperature like before?
Is it possible to use the Thermochrons to measure the internal temperature of large mammals?
Do I need to calibrate Thermochrons and Hygrochrons?


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 -40C to 85C 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.

http://www.maxim-ic.com/ds9107

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.

DS1921G
DS1922L/T
ds1923

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

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.

Other Probes
Other Partner Options

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

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
Waterproof Loggers
Thermochons are IP56 Rated (water resistant but not waterproof)

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.

All iButton Data Loggers

Q9: Where do I get software for the Thermochron?

The DS1921 Thermochron is supported by all of our SDK's listed below. If you would like to purchase a turnkey product for Thermochrons, please see our Solutions Search for all of our partners products.

1-Wire for Windows (TMEX)
1-Wire Public Domain Kit
1-Wire API for Java

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.

Calibration Services

Frequently Asked Questions