RFID Guide: Difference between revisions

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[[Category: Primer]]
{{#seo:|description=How does RFID work? Learn how frequency, protocol, and chipset impacts reader compatibility.}}
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== What is RFID? ==
 
RFID, short for Radio Frequency Identification, is a system for identifying the presence of objects by attaching small "tags" that contain a unique identifying code. The code can be read when the tag comes within range of an RFID reader.
 
 
 
{{HoverImageNoLink|TagReadH.jpg|TagRead.gif|link=}}
 
 
 
RFID technology is used in a wide array of applications, for example-
* Building security and access control
* Tracking library books
* Tracking farm animals or wildlife
* Interactive museum exhibits
 
===How Does RFID Work?===
The RFID tag contains a loop of copper wire (or a thin copper circuit trace) connected to a tiny chip. The RFID reader has a large antenna that emits an electromagnetic field that will induce current in the copper loop inside any nearby tags. When the tag is energized in this way, the chip is programmed to broadcast its data to the RFID reader.
 
[[Image:RFID-diagram.jpg|link=|750px]]
 
Because of how inductive power works, the surface of the tag needs to be approximately parallel to the surface of the reader. If the tag is perpendicular to the reader (i.e. the edge of the card resting on the reader), the tag may not receive power at all.
 
The distance at which the tag can be read depends on the size of both antennas, and also on the reader's operating frequency. Phidgets RFID readers and tags operate in the LF (Low-Frequency) band, which results in read distances of 5 to 10 centimeters.
 
==How Can I Use RFID With Phidgets?==
 
Building a simple RFID system with Phidgets is easy. Here's everything you'll need:
 
[[Image:RFID-functional.jpg|link=|300px]]
* A [{{SERVER}}/?tier=1&catid=81&pcid=72 RFID reader], like the 1024 - PhidgetRFID Read/Write
* Some [{{SERVER}}/?tier=1&catid=47&pcid=40 RFID tags]
* A mini-USB cable
 
Next, go to the '''User Guide''' tab on the product page for your Phidget RFID reader. This will walk you through the installation of the Phidget libraries on your computer, and show you how to use the Phidget Control Panel to test out your Phidgets.
 
== Which RFID Tags Can I Use? ==
 
RFID is a very broad technology, with many different variants and options. All of the tags sold by Phidgets Inc. are compatible with our readers, but you may find you need tags that come in a different shape or form factor than what we offer. In order to check if an RFID tag can be used with a Phidgets RFID board, you should ensure that the '''Frequency''', '''Protocol''' and '''Chipset''' are all compatible.
 
===Antenna Frequency===
 
The antenna on our RFID boards operates within '''125-150 kHz''', also called "Low Frequency".
 


{|
{|
|- valign=middle
! Band || Frequency || Compatible with Phidgets
| align=center width=300px| __TOC__
|-
| [[Image:1023.jpg|200px|link=]]
| LF (Low Frequency)|| 125-150kHz || ✔️
| [[Image:tags.jpg|300px|link=]]
|-
| HF (High Frequency) || 13.56MHz || ❌
|-
| UHF (Ultra-High Frequency) || 300MHz - 3GHz || ❌
|}
|}


<br clear="all" />
===Tag Protocol===
==Introduction==
For '''read-only''' tags, the data on the tag must be encoded according to one of these standardized protocols:


RFID (radio frequency identification) systems use data strings stored inside RFID tags (or transponders) to uniquely identify people or objects when they are scanned by an RFID reader.  These types of systems are found in many applications such as passport protection, animal identification, inventory control systems, and secure access control systems.


==Principles of operation==
{|
RFID works on the same principle as a transformer.  When the reader is powered up, it gives power to a large coil.  The coil creates an external magnetic field which can then be paired with a coil inside a nearby tag.  This delivers a small amount of power wirelessly to the tag.  With that power, the tag is able to access a small internal memory bank and transmit a key string back to the reader via modulation on the wireless signal.
! Protocol || Encoding || Tag String || Compatible with Phidgets
|-
| EM4100 / EM4102|| Manchester || 10-digit hexadecimal (0-9, A-F) || ✔️
|-
| ISO11785 FDX-B || BiPhase || 15-digit numeric || ✔️
|-
| PhidgetTag (ASCII) || BiPhase || 24-character plain text || ✔️
|}


==RFID Protocols==


In order for an RFID reader like the [{{SERVER}}/products.php?product_id=1024 1024 - PhidgetRFID Read/Write] to communicate with an RFID tag, they must share a common protocol.  This protocol acts as a set of rules for the way data is transmitted wirelessly between the reader and tag. It's common for people to assume that an RFID tag and reader need only share the same operating frequency to be compatible, but they also need to use the same communication protocol. Check the user guide for your device to determine which protocols it supports.
For '''writable''' tags, the protocol is unimportant because they usually come blank, and if they are pre-written in an unsupported format, you can just rewrite them.  


Common RFID protocols:
===Tag Chipset===
*EM4100 Series
Each RFID tag contains a tiny microchip that determines how it communicates and what kind of special features it supports.
*ISO11784/ISO11785 (FDX-B)
*ISO18000-2
*ISO10536
*ISO14443
*ISO18000-3
*ISO18000-6
*EPC class 0
*EPC class 1
*EPC GEN II
*ISO18000-4
*Intellitag
*μ-chip


==Communication and Effectiveness==
For '''read-only''' tags, the chipset is unimportant as long as the tag data is encoded in one of the supported protocols listed in the section above this one.


RFID tags come in two main varieties: passive and active.  Active tags have their own power supply which they use to power an antenna to broadcast data.  Passive tags derive the power they require to operate directly from the RF output of the RFID reader, and no other power supply is necessary.  This makes passive tags cheaper to produce and much more suitable for common applications whereas active tags are used in situations where very large read distance is desirable(train cars for example are one of the few places active tags are used).


Because passive tags require a strong RF field to operate, their effective range is limited to an area in close proximity to the RFID reader.  In the case of the PhidgetRFID, tags brought within approximately 3-4” of the reader can be read. The distance over which the RFID tag is usable is affected by such things as the tag shape and size, materials being used in the area near the reader, and the orientation of the reader and tag in respect to each other and in their operating environment.  The smaller a tag, the closer it must be to the reader to operate. A reader's range cannot be increased with any sort of simple modification.
To use '''writable''' tags with Phidgets, the chipset must be '''T5577'''. Our RFID boards are only designed to write to tags with this specific chipset.  


Some varieties of tags such as T5577 support writing. These tags can have any protocol or data written to them.


==Multiple Readers==
{|
! Chipset || Writable using Phidgets
|-
| T5577 || ✔️
|-
| EM4305 || ❌
|}


Multiple RFID readers within 1 to 2 meters will interfere with each other.  This can be overcome in software by enabling the antennae of individual RFID readers in sequence. Starting with all readers disabled, enable the antenna of the first RFID reader. Wait for 100ms or more to detect any tags. Disable the antenna of the first reader and enable the antenna of the second, and perform another wait cycle etc...  This can cause some issues if the tag is expected to only be present for a short period of time since a particular reader may be inactive at that moment.


The other way to attack this problem is to shield the readers from one another. This is more difficult than it appears on the face of it however. In general this will involve placing metallic barriers between the readers of indeterminate size.  The shielding required will vary from set up to set up but sufficed to say, air on the side of more shielding than less shielding in all situations and it may end up that shielding just isn't not drastic enough to work for your system in which case you will have to revert to plan A which is the polling method.
When shopping for tags online, be aware that some products may list multiple chipsets (e.g. both T5577 and EM4305) in the product title, probably to maximize search results. In these cases, it's best to check the datasheet to confirm which chipset is actually present inside the tag.


==Multiple Tags==
== Can I Use Multiple Readers? ==


While some RFID readers offer the capability to read multiple tags at once, the majority do not.  In order to read a tag, any other tags must first be removed from the reader's field of effect.
If you try to use multiple RFID readers close to one another (in hopes of increasing your area of tag detection), you'll find that neither reader will be able to read the tag. This is because the antennas of the two readers interfere with one another, causing the tag to receive inconsistent power. The possible solutions are:


==RFID Tags==
* Move the readers further apart, until tag reading is consistent
* Use the antenna enable/disable function in our API to cycle through each reader (see [{{SERVER}}/?view=articles&article=MultipleRfidReadersCloseRange this article] for details)
* Use metallic barriers to shield the readers from one another (not recommended, difficult to do properly)


The PhidgetRFID can be used with any RFID tag designed for the EM4102 protocol.  RFID tags come in a variety of shapes and sizes to suit various applications.  All RFID tags '''of the same type''' sold by Phidgets are guaranteed to be uniquely identifiable, and are available as:
== Quick Links ==


*30mm Disc Tags
* [{{SERVER}}/?prodid=1023 Phidgets RFID Readers]
*Credit Card Sized Tags
* [{{SERVER}}/?view=comparetable&rel=RFIDTag Phidgets RFID Tags]
*Key Fob Tags (attach easily to key rings)
*Wrist Strap Tags
*'Nail' Tags (Could be hammered into a crate)
*Threaded Cylindrical Tags
*Bird Leg Ring Tag

Latest revision as of 20:06, 25 June 2024

What is RFID?

RFID, short for Radio Frequency Identification, is a system for identifying the presence of objects by attaching small "tags" that contain a unique identifying code. The code can be read when the tag comes within range of an RFID reader.


TagReadH.jpg TagRead.gif


RFID technology is used in a wide array of applications, for example-

  • Building security and access control
  • Tracking library books
  • Tracking farm animals or wildlife
  • Interactive museum exhibits

How Does RFID Work?

The RFID tag contains a loop of copper wire (or a thin copper circuit trace) connected to a tiny chip. The RFID reader has a large antenna that emits an electromagnetic field that will induce current in the copper loop inside any nearby tags. When the tag is energized in this way, the chip is programmed to broadcast its data to the RFID reader.

RFID-diagram.jpg

Because of how inductive power works, the surface of the tag needs to be approximately parallel to the surface of the reader. If the tag is perpendicular to the reader (i.e. the edge of the card resting on the reader), the tag may not receive power at all.

The distance at which the tag can be read depends on the size of both antennas, and also on the reader's operating frequency. Phidgets RFID readers and tags operate in the LF (Low-Frequency) band, which results in read distances of 5 to 10 centimeters.

How Can I Use RFID With Phidgets?

Building a simple RFID system with Phidgets is easy. Here's everything you'll need:

RFID-functional.jpg

Next, go to the User Guide tab on the product page for your Phidget RFID reader. This will walk you through the installation of the Phidget libraries on your computer, and show you how to use the Phidget Control Panel to test out your Phidgets.

Which RFID Tags Can I Use?

RFID is a very broad technology, with many different variants and options. All of the tags sold by Phidgets Inc. are compatible with our readers, but you may find you need tags that come in a different shape or form factor than what we offer. In order to check if an RFID tag can be used with a Phidgets RFID board, you should ensure that the Frequency, Protocol and Chipset are all compatible.

Antenna Frequency

The antenna on our RFID boards operates within 125-150 kHz, also called "Low Frequency".


Band Frequency Compatible with Phidgets
LF (Low Frequency) 125-150kHz ✔️
HF (High Frequency) 13.56MHz ❌
UHF (Ultra-High Frequency) 300MHz - 3GHz ❌

Tag Protocol

For read-only tags, the data on the tag must be encoded according to one of these standardized protocols:


Protocol Encoding Tag String Compatible with Phidgets
EM4100 / EM4102 Manchester 10-digit hexadecimal (0-9, A-F) ✔️
ISO11785 FDX-B BiPhase 15-digit numeric ✔️
PhidgetTag (ASCII) BiPhase 24-character plain text ✔️


For writable tags, the protocol is unimportant because they usually come blank, and if they are pre-written in an unsupported format, you can just rewrite them.

Tag Chipset

Each RFID tag contains a tiny microchip that determines how it communicates and what kind of special features it supports.

For read-only tags, the chipset is unimportant as long as the tag data is encoded in one of the supported protocols listed in the section above this one.


To use writable tags with Phidgets, the chipset must be T5577. Our RFID boards are only designed to write to tags with this specific chipset.


Chipset Writable using Phidgets
T5577 ✔️
EM4305 ❌


When shopping for tags online, be aware that some products may list multiple chipsets (e.g. both T5577 and EM4305) in the product title, probably to maximize search results. In these cases, it's best to check the datasheet to confirm which chipset is actually present inside the tag.

Can I Use Multiple Readers?

If you try to use multiple RFID readers close to one another (in hopes of increasing your area of tag detection), you'll find that neither reader will be able to read the tag. This is because the antennas of the two readers interfere with one another, causing the tag to receive inconsistent power. The possible solutions are:

  • Move the readers further apart, until tag reading is consistent
  • Use the antenna enable/disable function in our API to cycle through each reader (see this article for details)
  • Use metallic barriers to shield the readers from one another (not recommended, difficult to do properly)

Quick Links

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