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RFID 101

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RFID 101


Are there different types of RFID or they all lumped together as one technology?

There are primarily three basic types of RFID : Active, Passive, and Semi-passive.

In the passive category there are (3) key frequencies as listed below. TagNet focuses on the UHF band for the sheer volume of tags that can be read  simultaneously and the read distances. UHF is used primarily in Asset Tracking, Supply Chain, and Manufacturing applications. The EPCglobal GEN2 spec capable is capable of interrogating up to 1,000 tags per second.



What is the key difference between Passive and Active RFID?

With passive technology, the Reader transmits and the tag 'listens', with Active technology the tag transmits (is battery powered) and the reader 'listens'.  To summarize:


Requires Portal or Handheld reader to track movement of tagged objects. Read distance limited to ~20 feet.

Frequencies (LF – 125 KHz, HF - 13.56 MHz, UHF – 915 MHz)

Relatively inexpensive Tags - $0.15 to $5.00

Indefinite tag lifespan


Full battery power tags that beacon a given intervals. Much greater read distances – up to 150 feet. Tags ~ $25.00

Deployed where RTLS is required... uses RSSI (Received Signal Strength Indicator) to determine tag proximity, triangulation accuracy can vary based on walls and objects


How does Passive RFID work?

Radio frequency identification (RFID) is one of the most pervasive technologies making use of electromagnetic radiation in the RF band. An RFID system is based on the communication between two devices, a reader unit and a tag. In a passive ultra high frequency (UHF) RFID system, the reader transmits a modulated RF signal to the tag, consisting of an antenna and an integrated circuit chip powered only by the received RF energy. It responds via the modulation of its backscattering aperture (or radar cross section) linked to its input impedance. Thus, the reflection of electromagnetic waves is used for the transmission of data from the reader to the tag and vice versa. U.S. and Canada are in the 902–928 MHz frequency band as shown below along with other countries.


What is the difference between a Reader and an Antenna?

The Reader is the powered electronic IP device (on your network). Most Readers support 4 antennas (via 'ports') however some can go as high as (8) ports. The Antenna is what emits the RF signal and listens for the response from transponders (tags). The reader converts this signal modulation from analog to digital and forwards this data as instructed by TagNet's Reader Management module. Shown below is a collage of hardware platforms from popular manufacturers.


Aren't all antennas the same?

Antennas come in many shapes, sizes and performance categories encompassing far-field & near-field variants. Whereas UHF RFID readers follow an FCC standard and are regulated to their power output, antennas can make or break an implementation. They range from inexpensive general purpose indoor patch antennas to hi-gain IP68 outdoor antennas (either circularized polarized or linear) to flat or wire antennas for specialized applications.


How are Antennas connected to the reader?

Antennas are connected via coax cable, each end will have a specific connector to match the reader port as well as the antenna port. Most RFID readers use a RP-TNC connector and antennas can take the same, or a N type or SMA.  This is all based on the manufacturers preference and the market they are selling into.


Is the type of coax cable I use important?

Yes. there are (3) common coax types (LMR-195, LMR-240 and LMR-400). The thicker the cable the less RF loss.  For most applications with lengths below 15 ft the cable type is not that important. However when deploying longer lengths (>50 ft), LMR-400 is highly recommended to reduce signal loss.


Ok, can I make my own cables?

Yes, you certainly can if you have the right tools and know what your are doing.  Bulk cable reels can be purchased as well as the connectors and tools to assemble.  However this is not the same residential coax you would see at a home installation. It is highly recommended that you use the services of a low voltage cable installer to make up the cables as they do this on a volume basis and have the right expertise. One of the most frustrating aspects of an RFID installation is troubleshooting bad cables which can incur more cost that getting it done professionally. Alternatively, cable assemblies can premade to the exact lengths required... here is an an example of a cable vendor website where these can be configured & ordered.


How can I connect different cable ends to match my existing antennas?

There are many cable end adapters that can change a connector type to another type (e.g. RP-TNC to SMA), or reverse it from male to female or visa-versa. Here is an example of a cable vendor that provides many different types of common RFID adapters and 'gender benders'.


What are the considerations for mounting a Reader in my facility?

The antennas are coax cable connected to the Reader with the limiting factor being the distance of the coax (the longer the run the more Db loss is incurred). Given this fact, the Reader itself does not have to be anywhere in close proximity to the read zone (where the tag is being scanned) and is typically placed above the ceiling in a generally safe area that has power and network access. Based on the distances between various read points, a strategically located reader can support multiple read zones (not necessarily 1:1).  


How does the performance of my network affect by RFID implementation?

Managing a physical reader requires a synchronous (IP Socket) connection between TagNet Server and RFID reader and requires a quality LAN/WAN with a desired latency not greater than 50ms. For local deployments a VLAN can provide data segregation and consistency of communications.  Extreme spikes in network latency and/or packet loss can break the communication protocol between TagNet and readers incurring reader recovery methods that can incur downtime.


Aren't all RFID tags the same?

As with antennas, the type of tag chosen can make or break an implementation. There are literally hundreds of different tag types for application to various material substrates such as corrugated, wood, metal, plastic, liquids, etc. Picking the wrong tag for type of object can result in poor read rates which is not fault of the readers, antennas or managing software. These important choices are flushed out during the planning exercises offered by Stratum Global.


Can I apply a tag directly to metal?

Yes you can using a 'Metal Mount' tag. These can be either printed or rigid. However if you place a non-metal mount tag directly on metal it will detune to the point it may not even be readable from an inch away.


I see the term 'SmartLabel used frequently, what exactly is that?

A SmartLabel is essentially an RFID tag that comes out of a printer. It is an RFID inlay 'converted' into media (e.g. 2 x 4" label roll) that is encoded and printed at the same time. Essentially the RFID 'Inlay' pictured below is embedded into the label media.  See 'How do I Commission RFID Tags' section


Ok, so what is an RFID Inlay?

An inlay consists of a silicon chip and an antenna of various sizes bound together on a substrate film. These are manufactured in the millions and come in rolls of either 'wet' (adhesive) or 'dry' inlays.



I see the term 'Rigid' tag used frequently, what exactly is that?

A rigid tag is essentially an RFID inlay that has been encapsulated in polymer/plastic that protects that tag from the elements and provides a substrate where the tag can be adhered to an object. This adherence can either be mechanical (with screws) or adhesive based.


Does a bigger tag mean better performance?

Yes, in most all cases. With passive RFID tags the term 'size matters' holds true... the larger the RFID inlay (hence the size of the antenna), the more RF it can absorb to power up the chip thus the longer the read distance.  Looking at the picture above, you can see a tag the size of a Chiclet gum in the bottom right and a large 4" x 8" container tag in the background. They both could have the same chip but perform dramatically different at distance. This blog has helpful tips about tag selection(refer to SOAP section).


What does the term 'Tag Commissioning' mean?

Commissioning a tag means putting it 'into service' which implies attaching that commissioned tag to an object that needs to be managed, tracked, etc. The underlying software activities during commissioning represent either mapping that tag to an object identifier and optionally encoding that tag with a unique EPC (if not serialized already). Typically tags on medial rolls for printer operation have a default EPC and must be encoded to serialize them during the mapping operation. So in summary commissioning at tag does not imply actually writing to it (i.e. encoding) but associating its EPC in the TagNet repository with meaningful attributes to identify it as it is RFID scanned at various read points.


How long will an RFID tag last, that is continue to function?

Since RFID tags have no moving parts, they have an indefinite lifespan subject to the physical abuse and environmental conditions they are subject to. If a tag is exposed to outside weather conditions and is properly encapsulated, theoretically it can last indefinitely. Conversely, a paper smartlabel that is applied to a cardboard box and stored indoors at reasonable ambient temperatures, and without undue vibration and shock, would also have the same theoretical lifespan.


Is all the information about that tag stored on tag's chip?

Generally no as that would be impractical in most cases as the amount of on-board memory for data storage is very minimal. The tag is issued an EPC (Electronic Product Code) during the commissioning process which is essentially a 'License Plate' identifier. It is a hexadecimal value typically 96 bits (24 chars) or 128 bits (32 chars). During the commissioning process, this EPC is mapped to the Object identifier (e.g. Product #, Asset ID, Part #, etc.) on the Server and when the tag's EPC is read, all the information about that tag is gleaned and available for business logic and visualization. This server approach has no limits to that amount of object data that can be stored and associated with a given tag.  This is how TagNet operates (see closed-loop vs EPCglobal below). To learn more about UHF Gen2 Tag Memory constructs click this informative blog.


I have heard about memory banks on the tag chip, can I not just use that?

Gen2 tags have four memory banks (0-3).  The one of importance is referred to as 'User memory'. Typically the user memory is no more than 512 bits (64 chars) and any data can be stored there (written to the tag at some point). Where this can be beneficial are when tags are sent out to trading partners that do not have access to the server hosting the Tags EPC object data. Because the Gen2 spec is an open standard, they can read this user memory bank data. Some examples are to store the Lot # and Lot Expiry Date to this user area so when the tags are received they can be interrogated in real-time to determine what may be rejected Another common example is to store the Work Order or Order # so manufactured items can be identified in the field for sales and service. To learn more detail about UHF Gen2 Tag Memory click this informative blog.


What is an RFID Read Zone vs Gate vs Portal?

They are all similar but can support different use cases. An RFID Portal also referred to as an RFID gate, automatically registers the passage of RFID tagged objects as they travel through a choke point such as doorway, hallway, dock door, etc. The inventory state of those tagged objects then changes from location A to B.  A fixed 'Read Point' or 'Read Zone' typically refers to an area covered by one or many antennas that will register tagged objects when they appear but there is not a clear entry or exit point. Examples would be a machinery load or unload point, an RFID enabled work table or a defined work or inventory area. It is important to understand the Radio Frequency (RF) does not follow perpendicular lines and thus all read zones need to be contained so they don't bleed into unwanted areas. More can be learned on this topic here.


I hear a lot about IoT, what is it in simple terms?

The Internet of Things (IoT) describes the network of physical objects —“things”— that are embedded with sensors, software, and other technologies for the purpose of connecting and exchanging data with other devices and systems over the Internet.


Does TagNet support IoT?

TagNet manages RFID tags in the enterprise that represent those "things" and maintains data on their physical properties and movements. For example; in a manufacturing environment when a tagged object (e.g. WIP) is feed to process machinery (such as conveyor or robot), it can communicate to that equipment its manufacturing attributes and what operations need to be performed. The process equipment in turn, can communicate back to TagNet as to exactly what operations were performed and the environmental/machinery conditions at that time. This data is stored on the TagNet server linking to the unique license plate of each RFID Tag... wherever the tag goes so does the ability to communicate that data to other systems and devices.  The RFID tag is the method that enables machine to machine communications.


I've seen references to RAIN RFID, what exactly is it?

RAIN RFID is a global alliance promoting the universal adoption of UHF RFID technology in a way similar to other wireless technology organizations including NFC Forum, WiFi Alliance and Bluetooth SIG. RAIN uses the GS1 UHF Gen2 protocol which ISO/IEC has standardized as 18000-63. The word RAIN—an acronym derived from RAdio frequency IdentificatioN—is intended as a nod to the link between UHF RFID and the cloud, where RFID-based data can be stored, managed and shared via the Internet. A RAIN RFID solution uses a reader to read and write to a tagged item, manage the data and take action. RAIN is not a proprietary technology and more can be gleaned from this link.


Does TagNet support RAIN?

Yes. As with IoT, TagNet support the RAIN concepts with respect to enabling businesses and consumers to identify, locate, authenticate, and engage each tagged item.


Closed Loop applications vs. EPCglobal trading partner?

RFID applications can be broken down into two general categories 1) Closed-loop where RFID is used internally within the enterprise to gain efficiencies in material tracking and advanced workflow and 2) Trading partner compliancy where the Tagged material is a commodity with a distinct GTIN (Global Trade Item Number).

With respect to closed-loop, the EPC can be any unique nomenclature dictated by the organization, however for EPCglobal the EPC follows a very disciplined construct referred to as a SGTIN (or serialized GTIN). This is used in combination with GDSN which is much larger topic. To learn more about SGTIN constructs click this informative link.


Can I turn off or unplug the Reader whenever I want?

You can however there are two considerations: a) disconnecting an antenna while the reader is activated can short out a port and b) if TagNet is managing the reader it will attempt to recover the reader.


If I don't think the TagNet system is working, will simply power cycling the Reader help?

Rarely does this help unless significant configuration changes have been made. TagNet manages the readers very tightly and has built-in health monitoring capabilities. If it detects something is not right with network or the reader it will exercise the corrective action which may include socket resets to a full warm boot in addition to sending out email alerts.  The reader is not a light switch and should not be managed that way.


Is RFID Magic?

There are two camps of opinions of RFID based on one's understanding of the technology. One opinion is that it doesn't work at all and the other is that it has no limitations and can read through metal & liquids, and at any distance.  The reality is that it is somewhere in the middle based on the use case. The correct expectations need to be conveyed as to how RFID will perform based on your particular use case. This blog has helpful explanations about passive RFID in general and enforces the topics in this section.


Is there a physical limit to the number of tags that can be read at a given time?

The EPCglobal Gen2 specification is capable of interrogating (reading) up to 1,000 tags per second. Though there are few use cases that require this type of throughput it is reflective of the UHF frequency band and open air protocol. 


I've heard the term LLRP, what the heck is it and should I care?

LLRP stands for Low Level Reader Protocol and is the specification of how physical readers should communicate with software platforms like TagNet. Most all readers in North America today support LLRP which is an industry standard. It is not necessary for an end customer to understand this, only that the this is supported in TagNet and enables plug n' play capability for LLRP compliant readers.


What exactly is TagNet and does it have a special meaning?

TagNet was named after the concept of a 'Tag network' whereas that software platform is managing the visibility and movement of tags throughout the enterprise. The TagNet RFID 'Suite' encompasses all the components as detailed in the Intro & concepts section.


Who or what is Stratum Global?

Stratum Global is the company that developed TagNet. It markets the TagNet software platform through its network of national resellers as well providing direct implementation services for TagNet customers.


Why would I consider using RFID?

Shown below are key adoption points:

Will it provide a necessary functionality unavailable elsewhere?

Will it provide improved efficiencies that lower my operating costs?

Is it required to meet a customer or Industry mandate?


Why is RFID a good alternative over Barcode?

Where human factor of not scanning, and/or scanning incorrectly is causing errors

Where critical passive traceability is required (no human errors)

Where the durability of barcode labels is an issue

Where speed of scanning is an issue

Where readability is an issue


What are the key advantages of RFID over Barcode?

Not limited to line-of-sight

Tags are read at much faster speeds that Barcode

Many tags can be read at the same time

Tags can be used in harsher environments and can be reusable

Tags can be read through: dirt, paint, steam, mud, plastic, and wood

Passive RFID tags have virtually unlimited life

Unattended Interrogation enables ‘event’ Management

A human body does not have to pick up a device and pull a trigger

Exception management (prevent it before it happens!)

Exceptional Traceability

Gen2 Security – password protection & encryption


So my company purchased TagNet, can I implement this without any outside assistance?

Stratum has decades of investment in its TagNet software platform to insulate customers from the low level technical nuances of implementing RFID.  However there is much to consider with respect to readers, antennas, tags, integration, workflow, etc. Stratum Global staff can assist you immensely in your planning phase with training and mentoring to make your phase 1 a success. Our customers become empowered to take ownership of future phases as their confidence grows.


Do I need to be a programmer to implement TagNet?

Absolutely not. If your implementation involves integration (most do) there may be a binding profile that works for you. You may need developers on the backend to accept the event payload but this is only one aspect of the work involved. TagNet can be considered similar to an ERP, MES or Asset management implementation that needs to be configured and populated with data from business owners.


What does the term 'TagNet System Owner' mean?

Once a customer implements their first phase with the assistance of Stratum Global (or a certified SG partner), the customer needs to take ownership of the delivered system and nominate an individual that will be responsible for the ongoing success and health of the system. These duties include being the point person on any issues that arise with the system and may include making configuration changes as the system scales into other phases. Your implementation may be simple or very complex based on the use cases of RFID tracking that have been implemented. The responsibilities of the TSO can be minor to major based on the scale of what has been implemented (such as number of readers, business rules, integration, etc.).  There are many tools that the TSO can leverage such as training provided during the implementation, this Help guide and the Stratum Support site for FAQ's and Knowledge Base (KB).





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