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How to write and read NFC tags
An NFC chip is a small, wireless object that can store data and be read over short distances by an NFC-enabled device (e.g. smartphone). It is located inside an NFC tag. When data is stored on an NFC tag, this is usually referred to as writing or encoding.
The following explains in more detail
- how NFC tags can be read or written to
- how write protection works
- what information can be written to NFC tags
1. Reading NFC tags
An NFC-enabled device such as a smartphone or special NFC reader is required to read NFC tags correctly. If the NFC tag is held within a short distance (approx. 1 cm) of the NFC-enabled device, the device emits a weak electromagnetic field that activates the tag.
NFC tags can be read with Android smartphones, Windows smartphones and iPhones. An app can be used to read the tag. However, many Android smartphones and iPhones are now able to read NFC tags automatically (without an app).
NFC tags can also be read on a Windows PC. This requires an external NFC reader, which can be connected to the PC via a USB port.
1.1. Reading NFC tags with an iPhone
To read NFC tags with an iPhone, NFC does not need to be activated separately. The NFC function is automatically activated on all iPhones. If your iPhone has the iOS 13 update or higher, content can also be read without an app.
For all other iPhones, an NFC app such as NFC21 Tools is required. By the way: Apple airtags can also be read with NFC. This is possible because they are equipped with an NFC chip.
Simply read NFC tags with your iPhone? Click here for the step-by-step tutorial: Read iOS NFC tags with NFC21 reader
1.2. Reading NFC tags with Android
To read NFC tags with an Android, you should first check whether the NFC function is activated. This can be deactivated, but must be activated for the reading process.
You can find out how to check this here:
NFC tags can be read on newer Android smartphones without an app. However, there are also various apps for older smartphones that can be used to read the tags.
You can find a list of suitable apps here: Mobile NFC apps
Simply read NFC tags with your Android smartphone? Click here for a step-by-step tutorial: Read Android NFC tags
1.3. Reading NFC tags with a PC
NFC tags can also be read on a Windows PC. To do this, you need the free software NFC21-Reader, an external NFC reader and an NFC tag. Our starter kit offers you a suitable NFC reader including NFC tags to try out:
The NFC reader is able to read the NFC tag. The read information is then displayed in the NFC21 reader software.
Step-by-step instructions for reading with NFC21 tools can be found here.
1.4. Reading the UID of an NFC tag
An NFC tag Unique Identification Number, or UID for short, is the identification number that every NFC tag has. This is unique for each NFC tag and is used in applications such as access control and login processes. Readers recognise the UID of an NFC tag and then allow the user access.
You can find out how to read the UID of your NFC tag here: Read out NFC tag UID
2. Writing to NFC tags
NFC tags can not only be read, but also written with information. Various data types such as text, links, numbers and codes can be stored on an NFC tag. Please note the amount of data that can be stored on NFC chips. This can vary depending on the chip type. In our info text Overview of NFC chip types you will find further information on the storage capacities of different NFC chips and which data types are suitable for which NFC chip.
If you do not want to write NFC tags yourself, we will be happy to take over the coding process for you. Simply add "Coding" to your shopping basket in the corresponding number of products you have ordered.
2.1. Writing NFC tags with an iPhone
iPhones require an app to write to an NFC tag. The app NFC21 Tools is particularly suitable for this. Within the app, you can easily describe NFC tags with, for example
- a URL
- an SMS
- an iPhone shortcut
- a contact
- a WLAN access describe. Many more applications are possible!
Our tutorial will guide you step by step through the use of the app.
2.2. Writing NFC tags with Android
An app must also be used to write to Android smartphones. The NFC Tools and NXP Tag Writer apps are particularly suitable for this. NFC tags can be written with various information using apps. This includes a URL, an SMS, Wi-Fi access, an email, social media profiles and much more.
This tutorial shows you how NFC tags can be described using an Android smartphone: Describing Android NFC tags
2.3. Writing NFC tags with a PC
NFC tags can also be written on a PC. To do this, you need an NFC writer, as most computers do not have their own NFC interface. You will also need software for writing NFC tags. For software solutions for NFC on the PC, we offer our free NFC21 tools, including NFC21 Writer for writing NFC tags.
2.3.1. Writing with NFC21 tools and NFC Reader / Writer
Using a connected NFC Writer and the Software NFC21 Writer, you can write URLs, text or business cards to NFC tags. Write protection can also be set up. With the business licence, it is also possible to write to NFC tags in series. If you have several URLs and NFC tags, you can use an Excel spreadsheet to write to several NFC tags in quick succession.
Click here to download the software: https://tools.nfc21.de/toolsWin/
2.4. NFC tag write protection
What is write protection? Write protection on NFC tags prevents them from being overwritten if information has already been saved on the NFC chip. This prevents unauthorised persons from overwriting the NFC tag themselves.
A distinction must be made between two types of write protection:
Hard write protection: In this case, an NFC tag is write-protected, which cannot be undone. The information on the NFC chip can no longer be changed under any circumstances.
Write protection with NDEF password: In this case, an NFC tag can be overwritten if the required password is known. It is also possible to set read protection in addition to write protection.
We currently only offer hard write protection in our software and app.
When is which write protection suitable?
Hard write protection is particularly suitable for information that should never be changed. This includes, for example, links to portals in which data can be managed. In this case, the link should never change and all important information can be edited in the respective portal. This is the case with our vCard, for example.
Write protection with NDEF password is suitable if you intend to change the data on the NFC tag in the future. It is also suitable if links change when information is edited. This is the case, for example, when changing usernames on social media profiles, whereupon the link to the profile itself also changes.
Further information on the topic of write protection:
- Can the content of NFC tags be protected against overwriting?
- Are there NFC tags that can only be written to once?](https://www.nfc-tag-shop.de/info/faq/gibt-es-nfc-tags-die-nur-einmal-beschrieben-werden-koennen/)
2.5. Rewrite NFC tags
Both an empty NFC tag and an already written NFC tag can be rewritten. The prerequisite is that no write protection has been set.
To do this, the NFC tag must be written to as normal. If information has already been saved on the NFC tag, it is recommended to delete it beforehand, but this is not absolutely necessary. If the original content requires more memory than the new content, parts of the original content may still be present on the newly written NFC tag. This can be avoided by clearing the NFC tag. Most NFC apps also offer a delete function.
3. Managing NFC tags via NFC Smart
NFC tags can contain various information such as text, links and numbers. However, only a small amount of data can be written to an NFC chip.
In some cases, however, it is necessary to store more information on an NFC tag than the chip's memory capacity allows. The storage space is not sufficient for extensive texts or large image material.
More on the topic of information on NFC tags:
One possible solution to circumvent this problem is to link an NFC tag to an online service. In this case, an NFC tag only contains the URL that refers to the online service. Various functions can then be carried out in the online service and larger amounts of data can be managed.
Our NFC Smart Platform offers you comprehensive online services for your problem. Be it the digital business card with our NFC vCard, the linking of your website with a self-designed landing page with NFC-URL or the digital dog tag Dogtap. Discover more offers from NFC-Smart.
