Hands-On: Tag Placement Using EPC Hotspot

Overview

The Instant EPC Hotspot software is an application suite for all aspects of RFID systems, including tag location analysis and pallet optimization. All the experts use tag placement applications and this article should convince you why you need one. You can download a full working version for a trial 15 day period and see the application that created these graphics – epcHOTSPOT. The software runs on Windows-based PCs and connects to a variety of popular RFID readers.

Installing Instant EPC Hotspot

Instant EPC Hotspot is supplied as an electronic download. To install Instant EPC Hotspot for the first time download the HotspotInstall.exe from the website.


Figure 1.1 – Instant EPC Hotspot Download Site

Once downloaded double click on “HotspotInstall.exe” to start the installation procedure. This will cause a new application to appear which will guide you through the installation process.

If default settings are used, the Instant EPC Hotspot will install into C:/Program Files/Integral RFID/Instant EPC Hotspot 2.5/

Starting Instant EPC Hotsport

The Instant EPC Hotspot application can be started by double clicking on the InstantEPC Hotspot icon located on the desktop. The application will start by displaying the screen shown in figure 1.1 below, which indicates progress during startup.


Figure 1.1-Application Startup Screen

Once the application has completed its start-up procedure, it will display the screen shown in figure 1.2


Figure 1.2--Instant EPC Hotspot Main Screen

All options and modes offered by Instant EPC Hotspot are now accessible from this main screen and its associated menu bar, and are discussed in the rest of this user guide.

Chapter 2: RFID Test Theory

RFID systems for the supply chain are here to stay. But the systems in use, the UHF Class 0, Class 1 and Gen 2 systems are known to be adversely affected by two things: water and metal.

Water has the effect of absorbing the RFID energy meant for the tag. A tag placed on, or close to water is not able to gather enough energy to function, and a deadening effect it observed. Moving the tag away from the water will quickly restore the tags operation.

Metal has two effects that deaden the performance. Firstly, a tag close to metal will be deadened due to destructive radio reflections from the metal. Secondly, a tag actually touching metal will be shorted out across the antenna, again stopping it from working. Like the effect from water, this effect from metal is only temporary, and moving the tag away from the metal will quickly restore its performance.

Unfortunately many objects found in the supply chain today are made up of water, metal or a combination of both. Given this propensity of RF-unfriendly objects, the natural trend is for RFID to fail or to perform very badly. But with a little knowledge and characterization, the behavior of objects in the RFID supply chain can first be understood, predicted, and then importantly, improved.

Object Definitions

Throughout the supply chain, there are three common objects: the item, the case and the pallet.

An item level object is the atomic unit that makes up a case. An item may be an object such as a tin of soup, bottle of shampoo, or bar of soap.

A case is the encapsulation of numerous items, into a convenient package, such as a cardboard box, or a shrink-wrapped unit.

Finally, a pallet is a grouping of cases suitable for transportation.

RF Characterization – Item Level

The RF characterization process starts at the item level. For the majority of items found in the supply chain today, items fall into one of two RF categories. They are either RF-transparent, or RF-opaque.

RF-transparent items do not have any adverse affect on the readability of an RFID tag, and consequently a tag can be placed anywhere on the item without concern for its operational effectiveness.  Items that fall into this category are boxes of dried goods (cereals, powders), paper products and clothing etc…


Figure 2.1 – RF Characterization at the Item Level

RF-opaque items are items that adversely affect the performance of an RFID tag, to the point where it is not readable. In this situation it does not matter where the tag is placed, it will usually be un-readable. Items that fall into this category are water-based liquids, and items that are packaged in metal containers (canned-foods, aerosols, foil-wrapped items etc…)

RF Characterization – Case Level

The next level up from items is the case level. A case packed with items can be identified as having one of three categories. A case can be RF-transparent, in that an RFID tag will read well regardless of where it is placed on the case. Cases that often fall into this category are boxes of cereals, or clothing. A case can also be RF-opaque, in that an RFID tag will not read at any location on the case. Examples includes cases of aluminum foil, or cans of soda etc…

 
Figure 2.2 – RF Characterization at the Case Level

The third, and most prevalent type of case is the one that exhibits mixed RF-behavior. In these instances an RFID tag may not read at all when placed in one location, but moving the tag to another position on the case may cause it to read fully. This situation is usually caused when the contents of a case are items of RF-opaque materials, packed loosely, or intermingled with RF-transparent materials. Typical examples include consumer electronics (metal item, surrounded by polystyrene packaging), and bottles of wine (water based liquid, but when in case surrounded by lots of air).

RF Characterization – Pallet Level

The third object commonly found in the supply chain is the pallet. However unlike items and cases, characterizing the readability at the pallet level is based on two competing factors: readability of the case, and the number of cases on the pallet.

RF behavior of the case is the predominant factor in the pallet performance. However the number of cases can also be a factor. Current systems (Class 0 and Class 1) perform well with pallets less than about 50 or 60 cases. But at numbers higher than this, performance drops off, as the RFID systems are simply not quick enough to inventory numerous tags in the short time it takes to pass through a portal.

Given both of these factors however, pallets can also be characterized into one of three areas:

A pallet can be highly readable, in that an RFID portal will read the majority of RFID-labeled cases on the pallet. Success rates of 80% or greater are expected from highly readable pallets (i.e. 80% or greater of the cases are consistently read as the pallet travels through the portal). In reading this high percentage of cases, both outside facing tags and inside facing tags are read.

Pallets that fall into this category are usually made up from RF-transparent cases, and tend to have less than 50 cases stacked on the pallet.

 
Figure 2.3 – RF Characterization at the Case Level

A pallet can be classified with low readability. This means that an RFID portal will read less than 30% of cases on the pallet. Pallets that fall into this category are usually made up with RF-opaque cases, and/or contain many cases per pallet (>100). In many of these situations, the tags that are read are just the ones on the outside face of the pallet, and none of the inside tags are read at all.

The third, and most prevalent type of pallet is the one that exhibits a medium readability. This is defined as reading between 30% and 80% of cases as the pallet moves through a portal.  Pallets that fall into this category usually allow their outside facing tags to be read, as well as a few of the inner tags.

Progressional Analysis of RF Behavior

Figure 2.4 illustrates the progression of RF behavior as the packaging size increases.

What can be seen from this diagram is the natural tendency for readability to remain constant, or to improve. Typically the readability does not drop as the pack size moves from item level, to case level and then to a pallet level.


Figure 2.4 – Progressional RF Characterization

For example, a single item that is RF-transparent will typically enable a caseload of the product to be also RF-transparent. And likewise, assuming that the number of cases on a pallet is not greater than 100, the pallet will tend to be highly readable.

Conversely an item that is RF-opaque will have a tendency to form an RF-opaque case, and a pallet with low readability.

The diagram also shows a pathway for the readability to improve as pack size increases. This is purely an effect of the packaging, and is actually an effect that can be exploited by packaging experts.

For example, an item that is RF-opaque has already been seen to lend itself to RF-opaque cases. However if the item is packed sparsely in the case, or packed in a way so that there is a large amount of free-air in the case, then case readability will tend to the medium level, or even better, the RF-transparent level.

Tag Placement Analysis

The end goal of RFID in the supply chain is undoubtedly the ability to read the ID of every case stacked on every pallet at any point in the supply chain. However the realities of today are that RFID rarely gives this desired performance.

This trend towards less-than-perfect performance is due in part to the physics of RFID and the RF-behavior of the products being tagged, and is also due in part to immature technology.

As technology improves, so will the successes of RFID. However the fundamental physics of RFID will still be a major factor, and products that are RF-opaque today will likely be that way in the years to come.

Given this sobering fact, there are however methods and techniques that can be employed to raise the success rates of RFID. The most important of these is finding the location for tag placement that optimizes success. This strategy is known as tag placement analysis

Tag placement evaluation concerns finding the ideal location for an RFID tag on an item, case or pallet. On some RF-friendly products, tag location is not an issue, and the tag can be placed virtually anywhere on the product and still be readable at distance. However on other less RF-friendly products, tag placement is critical and will mean the difference between tag readability at 1 foot and readability at 10 feet.

Two methods are employed in Instant EPC Hotspot for locating the optimal tag location. The first method, known as “sweeping” is a quick and approximate method for determining tag location. The second method, “hotspot mapping” is an in-depth analysis, resulting in a carefully mapped 3D result set.

Tag Sweeping

The Tag Sweeping methodology takes a judgmental approach to finding the best tag location. Effectively, a tag is taped to the end of a plastic rod, or wand. This wand is held in the operator’s hand so that that tag is located firmly against the product face, and the operator is far enough away from the product so as to limit interference. The Instant EPC Hotspot uses an attached RFID reader to show immediate feedback of the tag readability. By moving the tag around the face of the product, a ‘feel’ for tag readability can be obtained.  The results of this test allow the operator to classify their test product as either RF-opaque, RF-friendly or mixed.

If a product is found to be RF-opaque or RF-transparent then no further testing is required; a tag will not read anywhere on an RF-opaque product, whereas a tag can be read everywhere on an RF-transparent product.

If the product is determined to be of mixed RF-behavior then further investigation is required, and the operator should perform a hotspot mapping exercise.

Hotspot Mapping

Hotspot Mapping treats the tag location issue as a solvable scientific problem that can be resolved by careful measurement and analysis. The surface of the product under test is mapped into a grid of 1-inch by 1-inch squares. For each location on the grid, an RFID tag is placed with its chip located on the grid intersection. Measurements are taken by software that controls a nearby reader and antenna, to measure the effective tag strength at the location. For each tag location, the evaluation of tag strength is a complex system of parametric tests, which exercise the tag over many of the frequencies used by the reader.

The results of this test are collected for each location on the product and then compiled into pictorial results. And from the pictorial results, the best tag location can easily be identified.

Chapter 3: The Main Screen

Instant EPC Hotspot operates in one of four modes: tools for looking at tag placement on single objects (items, cases, vials etc…), tools for looking at multiple tags with portals (pallets and containers), tools for reading tags in general, and tools for programming tags. With each mode comes a separate workspace, and a separate set of tools. These areas of functionality are all accessed from the main screen, as shown in figure 3.1. There are five buttons on this main screen:

New Case and Vial Workspace
Pressing this button (or selecting the same from the File menu) will instance a new workspace for tag location analysis. This workspace takes the form of a window with its own menubar and its own toolset. Chapter 4 details this workspace.

New Pallet and Container Workspace
Pressing this button (or selecting the same from the File menu) will instance a new workspace for portal analysis. This workspace takes the form of a window with its own menubar and its own toolset. Chapter 5 details this workspace.

Tools for Reading Tags
Pressing this button (or selecting the same from the File menu) will instance a new workspace with tools designed to optimize the reading of tags. This workspace takes the form of a window with its own menubar and its own toolset. Chapter 6 details this workspace.
Tools for Programming Tags
Pressing this button (or selecting the same from the File menu) will instance a new workspace with tools designed for programming of tags. This workspace takes the form of a window with its own menubar and its own toolset. Chapter 7 details this workspace.
Open Existing Workspace
Pressing the Open Existing Workspace button (or selecting the same from the File menu) will prompt the user to open a file. Depending on the type of file, a new workspace will be opened and the file read into it. Also accessible from the main screen are a small number of menu options. Included in these are:
File: Preferences
Will display the Preferences window. See chapter 8 for details.
File: Reader Setup
Will display the Reader Setup and Selection window. See chapter 9 for details.
Quit
The Quit menu item will cause Instant EPC Hotspot to exit.

Chapter 4: Case and Vial Workspace
Object Setup

All item and case level operations require details about the object being used. These details are entered in the Object Setup screen, accessible under the Actions menu, shown below in figure 4.1.
The Object Setup screen allows an object name, description, color, shape and dimensions to be entered. All dimensions are either in inches or cm, depending on the current user preferences setting.
The object can be selected to be one of the following basic shapes: box, cylinder or pyramid.


Figure 4.1 – Case Setup Screen

The model of the case shown to the right is a standard 3D interactive model. Details on how to interact with this model are found in appendix A.

Image Setup
Once the basic geometry of the object has been established, images can be imported and pasted onto the faces of the object. To do this, click the Image Setup icon on the left of the window. This will change the controls to those shown in figure 4.2.

Images can be loaded into the software by clicking on the Load Image From File… button. Doing so will prompt the user to select a JPG, GIF or PNG image from the file system.

Note: Images are automatically scaled down in size as they are loaded. There is no problem selecting a 5 mega-pixel photo for example.

Note: A scaled down copy of any image used is stored with the hotspot file. So deleting the original image from disk will not remove it from the hotspot model.

Once an image is loaded, the buttons above it can be used to apply or clear the image from a single face or all faces. When applying or clearing from a single face, the face being worked on is selected using the Face Selector list above the image.



Once a case geometry and images have been setup, there are two experimental tests that can be performed. These are the sweep test procedure and the hotspot test procedure. Both require setting up equipment before proceeding, as described in the next section.

Object Level Testing (Cases or Vials etc…)

For both the sweep and hotspot tests, the experimental set-up is the same. This setup comprises an RFID reader connected to a single antenna. The antenna can be either a linearly polarized antenna or circularly polarized.
Any equipment and tag combination can be used for the testing. However it is important that the same equipment, tags and set-up be used for all testing so that results can be compared across tests.

Figure 4.3 illustrates the generic setup required for all object level tests. Heights and distances do not need to be exactly as specified, but must be constant across all tests.




Figure 4.3 – Generic Setup for all Object-Level Testing

Description

Recommended Measurement

Center of Antenna to Front Face of Object

30 inches

Height of Center of Antenna from Ground

30 inches or greater

Height of Center of Front Face of Object from Ground

30 inches or greater

An antenna should be placed such that it faces the center of the front face of the test object. The center of the antenna should be aligned with the center of the object face, in both vertical and horizontal planes.

The front of the antenna should be 30 inches from the front of the test object.

The height of the entire test setup should be at least 30 inches from the ground.

The test platform should be void of metal fixtures and fittings. For example, do not use a metal test bench, or a test bench with metal supports. A wooden table is an effective test platform.

Sweep Test

The Sweep Test screen, accessible from the Action menu or by pressing the Sweep Test icon, displays the controls required to operate the sweep test for tag location analysis.

The center of the screen holds an interactive 3D model of the test object. Details on how to interact with this model are found in appendix A.

The bottom of the screen holds the standard RFID reader control panel, details of which can be found appendix C. For the purposes of sweep testing, the tag class should be selected appropriately to reflect the tag being used, the attenuation should be set to zero (maximum power), and the antenna should be selected to reflect the single antenna being used for the test.


Figure 4.4 – Sweep Test Screen

Pressing the start button (bottom right hand side of window) will cause the software to start using the attached RFID reader. The reader will attempt to read a single tag repeatedly, updating the screen accordingly.

As the operator moves a tag around a face of the test-object, the virtual object will alternate between red and green in color, reflecting the current state of the tag readability. These two colors are defined as:

Color

Meaning

Red

Tag cannot be read

Green

Tag can be read

Once the operator has finished performing a sweep test, and has made a judgment on the RF-behavior of the case, the Stop button should be pressed (bottom right of the screen).

After this the results for the object should be entered by selecting a suitable entry in the drop down menu entitled “Sweep Results”. There are four options to choose from:

Color

Meaning

Yellow

No result

Red

Case is RF-opaque

Grey

Case has mixed RF-behavior

Green

Case is RF-transparent

Sweep Test Experimental Procedure

In order to exercise effective sweep testing, an additional piece of hardware must be prepared. This hardware is called the tag rod, and is usually a plastic or wooden rod (RF-transparent material), with the test RFID tag attached to one end. The rod must be at least 12 inches long, and is designed to enable the operator to positiona tag in free-space without effecting the RF-field himself.

Figure 4.5 illustrates a simple tag rod. In this instance, a 12-inch plastic ruler is used as the rod, and a Class 1 tag is taped to one end of the rod.


Figure 4.5 – Tag Rod used for Sweep Testing

Using the Sweep Test screen for instant visual feedback, the operator should hold the rod at the end without the tag, in such a way as to force the tag to lie flat against a face of the test case.

At this point, the software will display either a red or green case on the screen, indicating whether the tag can be read or not (green implies readable, red implies not readable)

Figure 4.6 illustrates the sweep test in action.


Figure 4.6 – Using the Tag Rod to position the RFID tag on the test case

The tag should be moved slowly around the face of the test-object while watching the screen display. In this way a ‘sweeping’action can be used to get an overall impression of the tag readability all over the face of the object.

If the product inside the test-object is made predominantly of RF-transparent materials (paper, tissues, clothing, breakfast cereal etc…), the screen display will remain green for greater than 90% of the time. This indicates that the tag can be read just about everywhere, and that further hotspot analysis in not required. 


Figure 4.7 – A Tag placed in a readable position is depicted as a Green Case

If the product inside the test-object is made up of predominantly RF-opaque materials, the screen will display a Red case, indicating inability to read the tag. If the product exhibits this behavior, further hotspot analysis in not required. 


Figure 4.8 – A Tag placed in a non-readable position is depicted as a Red Case

The third and most common scenario is that the product inside the test-object is made up of RF-opaque materials, but there is packaging and air space also inside the case that act as RF-transparent materials. In this scenario the screen display will often change between Red and Green as the tag is moved around the face of the product. This indicates that the readability varies across the product, and warrants a full hotspot evaluation and mapping.

Note: Make sure that that tag is always firmly pressed against the test case. A gap of less than 1mm between the tag and the test-object can influence the results.

Note: If using a circular antenna, orientation of the tag to the reader is not important. However if the antenna used is a linear antenna, beware of the orientation of the tag to the antenna.

Note: Sweep testing is usually effective when both the front and back faces are swept. This gives a more realistic picture of the RF-behavior than just sweeping the front face.

Hotspot Test
Hotspot testing requires no additional hardware but may require the test object to be physically marked up prior to testing.

Preparation
The hotspot test involves measuring the strength of the RFID tag at different locations on a case. These locations are referenced using a 1-inch by 1-inch grid.  So in preparation for hotspot testing, it is useful that a test object be marked with a grid, as shown in figure 4.9.


Figure 4.9 – Marking up a test object with 1-inch by 1-inch grid

Once the test object is marked up, it must be placed in the required testing position, approximately 30 inches from an antenna, as shown in figure 4.3 earlier.

At this point, the Instant EPC Hotspot software can be used to drive the tag location testing. Select the Hotspot Test menu item from the Action menu to display the hotspot test screen.

The center of the screen holds an interactive 3D model of the test case. Details on how to interact with this model are found in appendix A.

The bottom of the screen holds the standard RFID reader control panel, details of which can be found in appendix C. For the purposes of hotspot testing, the tag class should be selected appropriately to reflect the tag being used, and the antenna should be selected to reflect the single antenna being used for the test. The software will control the attenuation settings automatically during the test.

Tag Type

The first part of the process is to select the tag type for testing. The tag type is selected using the drop down menu at the bottom of the hotspot screen, as shown in figure 4.10. It doesn’t matter to Instant EPC Hotspot which tag is actually used. What is important is that the same tag is used throughout the testing.

Tag types are represented not by the manufacturer or specific chip-type, but rather by physical size. Thus an Alien Squiggle tag is represented by the 1x4 inch tag option, as are similarly shaped tags from Avery and Rafsec.

Note: if the tag is to be used horizontally, the 4x1 inch tag option should be selected.

Tag Location

The idea behind the hotspot test is that the tag strength is measured at every location on the face of a case. In order to do this successfully the software must know where the tag is located when the measurements are made.

This is achieved by positioning a virtual tag on-screen, and then by physically positioning the real tag in the same location on the real case.

To specify the virtual tag position, click on the intersection of a grid marking on-screen. This will place the tag on the virtual case, centered at the intersection, as shown in figure 4.11.

Once the tag has been located on screen, apply the real tag to the corresponding location on the real case, as shown in figure 4.12


Figure 4.12 – Real Tag Placement

Tag Strength

Once the virtual tag and real tags have been placed, the system is now ready to begin measuring tag strength.
Click the Start button on the hotspot test screen (bottom right of screen). This will cause the software to activate the reader and the tag strength measurements to begin.

Once started, the software will continually repeat its tag strength measurements. Part of this procedure involves varying the attenuation (and hence power output) on the reader. This is manifested by the attenuation bar on the bottom right of the screen continually moving from high to low. At each power level, the tag is exercised using a variety of techniques.

Once all power levels have been used, a single test procedure is finished and tag strength reported. This tag strength is an abstract strength measurement, shown in the current result field at the top of the screen.

If left unattended the software will repeat the same test over and over again. In most situations, this repeated procedure will result in consistent tag strength measurements, plus or minus one point. This can be seen in the Last Results field at the top of the screen.

Repeated results that are not consistent are usually indicative of problems in the environment, such as sporadic RF interference or even human interaction with the test setup (such as people walking between the antenna and case).

Recording Tag Strength

When the last few results show consistency, the operator can record the data. This is achieved by clicking on the Record button at the bottom of the screen.

Recording tag strength has two implications. First, the average value from the last three tag strength measurements is recorded in visual, color-mapped form on the screen. This manifests itself as a red, green, or white marking at the position of the virtual tag.

The second implication is the movement of the virtual tag. The tag will be moved to the next location on the grid. This is an indication that the real tag must be moved to corresponding location.

Tag strength measurements will automatically continue, even while the operator is physically re-positioning the tag on the case.


Figure 4.14 – Tag Strength Recording

Once the real tag has been repositioned, the system should be allowed to make a few repeated measurements at this new location, until consistency is found. At this point, the Record button can be pressed again and the whole process repeated.

In repeating this entire process, the system will guide the operator through mapping out the entire face of a case.

If at any time a mistake is made, the Erase button can be used to wipe out the results at the current location.
Likewise, at any time the virtual tag can be re-positioned by clicking on the new grid-intersection. This way, whole blocks of locations can be skipped in the recording process.

Mapping a Back Face

It is very important to map the back face of a case as well as the front face. 
This is achieved by rotating the virtual case so as to expose the back-face. Once the back face is visible, the virtual tag can be placed on it and measurements made and recorded.

Note: the real case should not be rotated. The purpose of this test is to measure how well RF energy travels through the case to read a tag on the far side. So in the real setup, the front face should still be the one nearest to the antenna.

Creating A Final Report
                  
The last option under the Actions menu is the Summary Report option. This screen displays a report containing all of the data known about the test object.


Figure 4.15– Report Screen

By default the report is locked when displayed. In its locked format, the 3D interactive graphics cannot be changed. To change the graphics, by rotating the case or changing the view parameters, the report must first be unlocked.

Unlocking the report is achieved by clicking the unlock button on the bottom left of the screen. To lock the report again, click the button once more.

Once unlocked, a tag can be placed onto the test object by clicking on a grid intersection. This tag placement is identical to the methods use in the hotspot testing section.

The exact visual state of the report is saved with the test data so that subsequent, identical reports can easily be loaded and printed.

To print a report, simply click on the Print button at the bottom right of the screen.

Analyzing the Results

The report screen allows the operator to collate all of the test object information into a single page, and add a recommended tag placement. However deciding where to actually place the tag requires a little thought. Here are some simple guidelines to help with this selection:

1.If the sweep test indicated the case is completely RF-transparent, the tag can be placed anywhere, usually to the upper left of the case.
2.If the sweep test indicated the case is completely RF-opaque, the tag will not read well wherever it is placed.
3.If the sweep test indicated a mixed RF-behavior then the hotspot test results should be used to indicate tag placement.

When looking at hotspot data, the general strategy is to look for large areas of green color, representing areas where the tag can be read well.

However the front face should not be the only one considered. The best location for a tag is usually one that allows it to be read from both the back of the case and the front. For example, figure 4.16 shows some real test results from a case.

Clearly there are large areas of green on the front face, and it could easily be assumed that the best tag location would be towards the left of the front face.

However when the case is made transparent so as to show the back-face mapping results, the story becomes a little more interesting. This is illustrated in figure 4.17.

This picture shows a large area of red, mapped to the back-face, left hand side. This indicates that there is some RF-opaque material behind the front-face that is stopping the RF from penetrating all the way to the back.

Thus if a tag were to be placed at the ideal front-face location, a case on the outside of a pallet would undoubtedly read well, but a case positioned just behind it would fail to read at all.

So to optimize the chances of reading stacked cases on a pallet, a location must be identified that allows for some transmission of the RF-energy. In the example, such a location is identified just to the right of the front face. Correspondingly, a tag placed on the back-face at this location also shows good read results, and it can be concluded that this position would give the best results for stacked cases.

Another consideration in tag location placement is the size of the green area. Sometimes there are just narrow bands of green surrounded by lots of red. Deciding on the best location here depends on the subsequent tag application technique:

If the tag is to be applied automatically, it can be assumed that tag placement will be within ±0.1 inches of the recommended location.

However if the tag is to be applied manually (slap and ship), then it must be assumed that the tag will actually end up within ±1 inch of the desired location.

So when looking at the preferred tag location for slap-and-ship application, take into account the fact that the tag may be placed around the ideal location and not on it. In this case, a small area of green surrounded by lots of red may not be the best location for the tag.


Figure 4.18– Recommended final tag placement for this product

Chapter 5: Pallet and Container Level Testing

Pallet and container level testing is the natural progression from case or item level testing.

Case and vial-level testing should be performed to find the best location to place an RFID tag on a case of product or single item. After that, items can be stacked into pallet or container formation and the collection’s readability investigated.

Given that the best location for a tag has already been found, the tools detailed below can be used to identify what is, and what is not being read, information that can then lead to a series of experiments aimed at improving container success rates.

However before any of this can be done, a 3D model of the container under investigation must be created. This is achieved using the Pallet and Container Setup menu item under the Actions menu.

Pallet Setup

The Pallet Setup screen allows the user to design and build uniform and non-uniform pallets in 3D.

Initially the Pallet Setup screen will appear empty, as shown below in figure 5.1.


Figure 5.1 – An empty pallet setup screen

This screen allows a name, description and dimensions to be input. Also a choice is provided to define either cases on a pallet, or items in a cardboard box. This choice only affects the visual display of the container itself (a pallet or tray is shown). It does not affect the contents at all.
.
Layer Editor
The Layer Editor is used to design the content of the pallet on a layer-by-layer basis. It is shown below in figure 5.2. The Layer Editor is split into four main areas:

Layer Selector: a sliding control that determines which layer to edit. Layer 1 is the bottom layer of a pallet.

Birds Eye Editor: A drag-and-drop editor that allows cases to be added, moved and deleted on each layer.

Case Selector: Allows the case SKUs to be loaded and used for pallet building

Pallet Model: A 3D composite of the pallet as it is being built

A pallet is built up using the following workflow:

  1. Select the layer to edit using the Layer Selector. (The total number of layers in a pallet is defined in the Pallet Setup screen).
  2. Load in the Case Definitions. For each different SKU type to be used in the pallet, the case must have already been defined using the Case Tools described in Chapter 4. Case definitions are loaded into the builder by selecting an empty slot (numbered 1 through 10) and then pressing the Load Case Definition button.
  3. Add a case to the pallet layer. This is achieved by drag-and-dropping a case definition from the bottom of the screen to the birds-eye grid.Hint: Holding the shift key down while dragging a case will rotate it 90 degrees.

Once cases have been added to the birds-eye view, they can be moved around and edited. A right-click on a case, or a selection of cases will bring up a pop-up menu with additional editing options. This is shown in figure 5.3.

The menu can be used to selection, copy, paste and delete cases. It can also be used to rotate or flip the selection.

Note: As cases are added, edited and moved in the birds-eye editor, the 3D pallet view updates in real-time to represent the current state of the pallet.

Hint: Many pallets are built with regular stacking patterns that alternate from layer to layer. It is easy with this editor to build one layer, then select all the cases, copy them, and then paste them into to next layer. At this point the entire layer can be flipped or rotated as required.


Figure 5.4 – Cases (2 normal and 1 rotated) are added to the layer

When multi-layered pallets are being built and edited, the layer to edit can be selected by clicking on the layer slider on the top left of the screen. The 3D pallet view indicates which layer is currently being edited by making it solid and all other layers wireframe. This is shown in figure 5.4.

Pallet Stacker

Once a pallet or container has been built the user can then select the Pallet Stacker menu item to move to the second setup process.

The pallet stacker is concerned with physically building a pallet with RFID-tagged cases. The software will guide the operator through building the pallet, one case at a time, and in this way the software can learn which RFID tag is located in which position in the pallet.

To prepare for stacking, it is recommended to have an empty pallet tray, a stack of cases already with RFID tags applied, and close access to a reader and antenna.

The operation of building a pallet is essentially a system of:

  1. Pick up a random case from the assembled pile
  2. Present the case, with RFID tag, to the reader
  3. When the software acknowledges the tag, place the case onto the pallet in the location indicated by the software.

 

The pallet stacker screen is shown in figure 5.5. It comprises the usual assembly of reader control panel, a central 3D pallet view and a few controls at the top of the screen.


Figure 5.5 – Pallet Stacker Screen

Pallet Stacking is initiated by pressing the Start button (bottom right of screen).

Once started, the software will begin reading tags. If the software finds a tag, and manages to read it ten times in succession, it assumes that it is part of a case presented to the antenna by the user. The software will indicate this by displaying the message “Assigned” at the top of the screen and playing a short sound.

On seeing the assigned message, the case should be placed on the pallet at the position marked by the pink case on the screen.

Once assigned, the pink case will jump to the next position in the pallet, ready for the next case to be presented and assigned.

In this way, the entire pallet can eventually be built up.


Figure 5.6 – Building the pallet, case by case.

At any point the stacking can be stopped by clicking on the Stop button.

The position of the pink case (the case to be assigned) can also be changed manually by typing in a new layer and item number into the green text areas at the top of the screen.
Note: All of the assigned tag IDs, and case locations are saved with the rest of the case and pallet data when the File menu, Save option is selected.

Pallet Reader

Once a pallet or container has been successfully built and cases assigned, the user is now ready to being pallet level testing.

Pallet level testing simply involves running the test pallet though an RFID portal (or container through an RFID tunnel)

Instant EPC Hotspot will control the portal, and based on results from the reader, will display the pallet in real-time on the screen

 


Figure 5.7 – Pallet Reader

When the Pallet Reader screen is first displayed, it shows the entire pallet, as shown in figure 5.7

To start the software, press the Start button (bottom right hand corner of the screen). This will cause the software to turn on the RFID reader and start looking for tags.

As the reader reads tags, the corresponding cases will be removed from the virtual pallet in real-time. In this way, the RFID reading for the whole pallet can be visualized. Counters at the top of the screen also indicate the current read state of the pallet.


Figure 5.8 – Pallet Reader showing cases that have not yet been read.

At any time, the information displayed can be selected from the menu on the left of the screen. The options include:

Tags Not Read
Display the tagged objects that have not yet been seen by the reader. Items will disappear from the screen as a pallet is pushed through a portal.

Tags Read
Display the tagged objects only if they have been read by the reader. Objects will appear on the screen as a pallet is pushed through a portal.

All Tags
Display all objects regardless of their read-state.

Antenna Visibility
Display tags only if they have been read, but color-code each item depending on the antenna that last saw it. This allows a view to be built of which antenna is reading which object. Very useful for tuning the antenna directions and placements in a portal.

Read Count
The read count display shows items only if they are seen by the reader. Initially items will appear on screen as white objects. As the tag is read over-and-over again by the reader, the object on screen will turn a darker shade of green.

The slider bar allows a greater control of which objects are displayed in this mode. The slider number represents the number of times a tag is read. If a tag has not been read, it will never appear on the screen. Otherwise, if the tag is read between 1 and ‘n’ times (where ‘n’ is the slider value) it will be displayed. If the tag has been read more than ‘n’ times, it will disappear from the screen again.

The purpose of this slider option is to view the ‘weak’ tags only – to hide the tags that have been read over-and-over again, and just to expose those that have been read a few times.

Reset
To reset the pallet to an ‘all unread’ state, simply click on the Reset button at the top of the screen.

Snapshot for Report
To take a snapshot of the current settings for the report screen, simply click on the Snapshot button.

Creating A Final Report
The last option under the Actions menu is the Summary Report option. This screen displays a report containing all of the data known about the test pallet.


Figure 5.9– Report Screen

By default the report is locked when displayed. In its locked format, the 3D interactive graphics cannot be changed. To change the graphics, by rotating the case or changing the view parameters, the report must first be unlocked.

Unlocking the report is achieved by clicking the unlock button on the bottom left of the screen. To lock the report again, click the button once more.

Once unlocked, the pallet visualization options can be edited and changed.

The exact visual state of the report is saved with the test data so that subsequent, identical reports can easily be loaded and printed.

To print a report, simply click on the Print button at the bottom right of the screen.

Chapter 6: Tools for Reading Tags

The Tools for Reading Tags workspace offers access to a number of tools useful for general RFID reading activity.

Readometer

The first of these tools is the Readometer application, as shown in figure 6.1.

The readometer is designed to use an RFID reader to look for one tag, and one tag only. The reader is instructed to look for a tag over-and-over again, as quickly as it can.

If a tag is not found, the message “No Tag” is displayed, and the background color is set to red.

If a tag is found, the tag ID number is displayed in the center of the screen and the background color turns green. Information about the tag type is displayed below this, and if the tag contains a valid EPC number, this is also displayed at the bottom of the screen.

As with all tools and reader applications, the Start button must be pressed to initiate reading. To stop reading tags press the Stop button or close the window.

The RFID reader can be controlled using the standard reader toolbar at the bottom of the screen. Settings such as antenna selection, tag type selection and attenuation can be altered.


Figure 6.1 – Readometer Application

Conveyor Reader

The conveyor tool is designed to aid testing on a high-speed conveyor system, as required by Wal-Mart and the like.


Figure 6.2 – Conveyor Application

As with all tools and reader applications, the Start button must be pressed to initiate reading. To stop reading tags press the Stop button or close the window.

The reader can be controlled using the standard reader toolbar at the bottom of the screen. Settings such as antenna selection, tag type selection and attenuation can be altered.

On pressing Start, the reader is put into single-tag mode and is told to read tags. As tags are read, they are displayed on the screen, along with the number of times the tag has been read in brackets.

The default persist time (how long a tag image remains on the screen) is 500 milliseconds. This can be changed using the Persist Time drop-down menu on the screen.

Portal Reader

The third tool useful for RFID activity is the portal reader. This application, shown below in figure 6.3, displays a real-time view of tags in read-proximity of the current RFID reader.

As with all tools and reader applications, the Start button must be pressed to initiate reading. To stop reading tags press the Stop button or close the window.

The reader can be controlled using the standard reader toolbar at the bottom of the screen. Settings such as antenna selection, tag type selection and attenuation can be altered.


Figure 6.3 – Portal Reader Application

Once the application has started, all tags that are read by the reader are displayed as icons on the screen. Each icon contains the following information:

Tag ID: The unique ID number of the tag in hexadecimal format
Image: Either a default sun image, color and labeled by tag type (green is Class 1, Blue is Gen 2 etc…), or a custom image defined by the user (see Preferences, Tag Images)
Timer: This is the persist time. Once the timer drops to zero, the tag will disappear from the screen.
Read Info: The number of times the tag has been read, and the antenna number that tag was last read by.

By default the screen shows a grid of 4x2 images. This display size can be changed using the drop down menu labeled Display Size.

The default persist time (how long a tag image remains on the screen) is 3 seconds. This can be changed using the Persist Time drop-down menu on the screen.

Tag Images
The default images for all tags are the ‘sun’ shapes, colored by tag type (green is Gen2, blue is Class 1, red is Class 0). However all of these images can be redefined on a per-tag basis. This is achieved using the Tag Images application (see next section).

The Tag Images application allows images to be defined for each tag and then saved in a hotspot file. At any time, a valid hotspot file can be loaded via the file menu, and these tag-image associations be applied.

Thus to install a set of tag images:

  1. Select the Portal Application
  2. From the file menu select “Open Tag Image Dataset”
  3. Load in the desired data set
  4. Reading the appropriately defined tags using the Portal Application will now cause the relevant images to appear

Tag Images

The Tag Images application allows for pictures to be associated directly with a tag ID. This is very useful for demonstrations and applications when specific tags need to be identified easily.

The tag images application is split into two sides: on the left is the image pallet and on the right is the tag grid.


Figure 6.4 – Tag Images Application

Image Pallet
The image pallet is used to load and select images. Images can be loaded into the pallet by selecting one of two buttons. The Load Image File button is used to load a single JPG, GIF or PNG file. The Load Image Folder is used to load all images inside the given folder. As images are loaded, a thumbnail appears in the image pallet.

Tag Grid
The tag grid on the right hand side is a simplified version of the Portal Application. Pressing the Start button will cause the attached reader to read tags, displaying tag icons as they appear.

Pressing the Clear Tags button will clear the tag grid.

Image Association
To associate an image with a tag:

  1. Select the image to use by clicking on it
  2. Drag the selected image from the image pallet, and drop it onto the tag to associate it with

All tag image data is collected in Tag Image Dataset. Tag Image Sets can be saved and loaded using the File menu.

Once tag image datasets have been defined, they can be used within the Portal Application as well as the Tag Images application.

Note: The images are not stored in the Tag Image Dataset – just a file reference is stored.

Chapter 7: Tools for Programming Tags

The Tools for Programming Workspace offers access to a number of tools useful for general RFID programming activity.

HEX Programmer

The HEX Programmer screen allows tags to be programmed one at a time, specifying the tag ID number in Hexadecimal format.


Figure 7.1 – HEX Programmer Application

The top half of the screen shows the tag ID editor, where tag ID data is entered as hexadecimal text. Most tags (class 0+, class 1 and Gen2) hold a 96-bit tag ID, which translates to 12 pairs of hexadecimal characters.

White spaces can be entered into the tag ID string – these will be stripped out before programming the tag.

Pressing the Start button will commence tag reading. The hexadecimal ID of a single tag will be shown on the screen if a tag is readable.

Pressing the Program Tag button will attempt to program the tag with the ID represented by the ID editor at the top of the screen.

The Decode button is used to transfer the ID from the tag currently being read into the tag ID editor at the top of the screen.

Once a tag has been successfully programmed, the tag ID will automatically be incremented, ready for the next tag to be programmed. The size of this increment is determined by the auto increment editor, also at the top of the screen.

Note: In order for tag programming to work, attenuation levels should be low (power should be high) and there should only be one class of tag selected.

EPC Programmer

The EPC Programmer screen allows tags to be programmed one at a time, specifying the tag ID number as an EPC construct.


Figure 7.2 – EPC Programmer Application

The top half of the screen shows the tag ID editor, where tag ID data is entered as an EPC construct.

Pressing the Start button will commence tag reading. The hexadecimal ID of a single tag will be shown on the screen if a tag is readable.

Pressing the Program Tag button will attempt to program the tag with the ID represented by the ID editor at the top of the screen.

The Decode button is used to transfer the ID from the tag currently being read into the tag ID editor at the top of the screen.

Once a tag has been successfully programmed, the serial number of the tag ID will automatically be incremented by one (1), ready for the next tag to be programmed.

Note: In order for tag programming to work, attenuation levels should be low (power should be high) and there should only be one class of tag selected.

Multi-Programmer

The Multi-Programmer screen allows many tags to be programmed in sequence.


Figure 7.3 – Multi Tag Programmer Application

The top half of the screen shows the tag ID editor, where tag ID data is entered as Hexadecimal text.

The Multi Programmer works in an automated way to program multiple tags in sequence. To start this batch programming, press the Start button.

To program tags in sequence simply wave each tag, one at a time, in front of the reader.  As this is done, the tag will be programmed with the next ID code in the sequence.

As each tag is programmed, a list will build up in the center of the screen showing the history of programmed tags.

Once a tag has been successfully programmed, the serial number of the tag ID will automatically be incremented, ready for the next tag to be programmed. The size of this increment is specified in the Auto Increment editor, also at the top of the screen.

Note: In order for tag programming to work, attenuation levels should be low (power should be high) and there should only be one class of tag selected.

Chapter 8: Preferences
There are a number of user preferences that can be set for Instant EPC Hotspot. The preferences can be accessed from the File menu.

Selecting the Preferences menu item will cause the window in figure 8.1 to appear.

Units of Measurement

The default unit of measurement for Instant EPC Hotspot is inches. This can be changed to centimeters by selecting the appropriate preference.

When inches are selected, the hotspot grid markings are set at 1 inch x 1 inch.

When cm are selected, the hotspot grid is set at 2.5cm x 2.5cm.


Figure 8.1 – Units of Measurement Preference

Tag Images

The tag images preference allows the default images to be changed for the Portal Reader application under the Tools menu.

By default, each tag that is found in this application is displayed with an image of a sun, color-coded and labeled according to the tag type (i.e. Class 1 tags are shown as blue, Gen 2 as green etc….).

This default image can be replaced by a user defined one using this preference window.

Simply select a custom image using the file browser (click on the ‘…’ button). File types supported are JPG, PNG and GIF.

Once a custom image has been selected, all tags found will be displayed with this image.


Figure 8.2 – Tag Images Preference


Figure 8.3 – The Portal Reader Application using default tag images


Figure 8.4 – The Portal Reader Application using a custom tag image

Chapter 9: Reader Setup and Selections

Reader Setup
Integration with off-the-shelf RFID readers is an essential part of Instant EPC Hotspot.

By default the software supports many commercial readers, and also allows additional readers to be added by third party developers (see the Reader Interface Development Kit document for more information).

To configure Instant EPC Hotspot to use a particular reader the operator must use the Reader Setup window, accessible under the File menu. This window is shown in figure 9.1. This setup window can also be accessed using the Reader Selector found on the toolbar (bottom left of screen).


Figure 9.1 – The Reader Setup Window

From the reader setup window, new readers can be added, or existing readers can be edited and deleted.

To add a new reader, simply select the New… button. This will cause another window to pop-up, as shown in figure 9.2


Figure 9.2 – The Reader Editor Window

The Reader Editor window contains the following options:

Reader Type
The Instant EPC Hotspot software will work with many commercial readers. The list of readers available is shown in the reader type pull-down menu. Select the desired reader from this menu.

Reader Connectivity
RFID readers either connect to the PC via RS232 serial cable, or via the network. The connectivity settings allow the selection of these parameters.

Test
Once the reader connection settings have been entered, pressing the Test button will attempt to contact the reader.

If the reader is working and the settings have been entered correctly, the results of the test will show the reader type and the current firmware version of the reader.

If an error occurred trying to contact the reader, the word “Error” will be displayed next to the reader type. Check your connection options and make sure the reader is powered on.

Note: The Instant EPC Hotspot software will save reader settings automatically.

Reader Selection

Once a reader connection has been defined (or once many connections have been defined), the reader setup window can be dismissed by pressing the OK button.

This will return control to the main window. Because many reader connections can be defined, the actual reader to be used with any particular application must be selected.

This selection is made from the toolbar at the bottom of the screen. The left hand side of this toolbar shows a popup-list of all the reader connections already defined.  Simply select the reader from this pop-up list to use it, as shown in figure 9.3.

Appendix A – Interactive 3D Cases

Many options in a Case and Vial Workspace depict a 3D virtual object on the screen. This object is fully interactive, allowing the user to rotate, scale and change its appearance.

Rotating an Object in 3D

To rotate an object in 3D, move the mouse over the object and press and hold down the left mouse button. As the mouse is moved, the case will rotate.

Releasing the mouse button will release control of the case rotation.

Scaling a Object in 3D

To scale an object in 3D (making it larger or smaller), move the mouse over the object. Then press and hold the shift key on the keyboard, and then press and hold the left mouse button.

Moving the mouse up and down with the shift key held down will cause the object to scale up and down.

Releasing the mouse button will release control of the object scaling.

Changing the Object Appearance

The visual appearance of the object can be changed by the user. To change the appearance, move the mouse over the object and click the right mouse button. This will cause a pop-up menu to appear, as shown below, offering the following choices:


Figure A.1- Viewing Options are offered via a Pop-Up menu

Wireframe Mode
Solid Mode
The Wireframe Mode menu item toggles between solid representation of a case and a transparent wireframe mode. Placing a case into wireframe mode is useful for seeing back-face mapping results.

Figure A.2- Wireframe case with grids turned off – A useful option for looking at back-face hotspot data

Grid
The inch x inch grid can be toggled on or off by selecting this menu.

Hotspot Data
The Hotspot data (color mapping) can be toggled on or off by selecting this menu

Custom Image Data
The Custom Image data, if present can be toggled on or off. Custom images are usually product labels etc… that cover the face of an object.

Text Labels
The text labels (Front, Top, Left etc…) can be toggled on or off using this menu option.

Auto Rotate
Selecting auto rotate will cause the case to automatically spin in 3D. The case will only stop spinning when Auto Rotate is turned off. The direction and speed of the rotation can be altered by dragging the mouse over the 3D object while the left-button is pressed.

Copy Image To Clipboard
Selecting this option will copy the current image onto the clipboard. The image can then be pasted into other applications such as Microsoft Word and PowerPoint.

Save As Gif Image
This menu option will allow the image to be saved as a transparent Gif image.

Reset View
Selecting Reset View will restore the default rotation and scale settings to the case.

Appendix B – Interactive 3D Pallets

Many options in the Pallet and Container Workspace depict a 3D virtual pallet on the screen. This pallet is fully interactive, allowing the user to rotate, scale and change its appearance.

Rotating a Pallet in 3D

To rotate a pallet in 3D, move the mouse over the pallet and press and hold down the left mouse button. As the mouse is moved, the pallet will rotate.

Releasing the mouse button will release control of the pallet rotation.

Scaling a Pallet in 3D

To scale a pallet in 3D (making it larger or smaller), move the mouse over the pallet. Then press and hold the shift key on the keyboard, and then press and hold the left mouse button.

Moving the mouse up and down with the shift key held down will cause the pallet to scale up and down.

Releasing the mouse button will release control of the pallet scaling.

Changing the Pallet Appearance

The visual appearance of the pallet can be changed by the user. To change the appearance, move the mouse over the pallet and click the right mouse button. This will cause a pop-up menu to appear, as shown below, offering the following choices:




Hide Wireframe Objects
Many screens displaying a pallet actually display some cases as not read (usually solid), and some as read (usually wireframe). At any time, using the Hide Wireframe option, the wireframe objects can be completely hidden, often making things easier to see.

Figure B.2- Wireframe Objects Displayed and Hidden

Hotspot Data
The Hotspot data (color mapping) can be toggled on or off by selecting this menu

Custom Image Data
The Custom Image data, if present can be toggled on or off. Custom images are usually product labels etc… that cover the face of an object.

Text Labels
The text labels (Front, Top, Left etc…) can be toggled on or off using this menu option.

RFID Tag
If RFID tags have been placed on cases or vials, they can be toggled on and off with this menu item.

Auto Rotate
Selecting auto rotate will cause the pallet to automatically spin in 3D. The pallet will only stop spinning when Auto Rotate is turned off. The direction and speed of the rotation can be altered by dragging the mouse over the 3D object while the button is pressed.

Copy Image To Clipboard
Selecting this option will copy the current image onto the clipboard. The image can then be pasted into other applications such as Microsoft Word and PowerPoint.

Save As Gif Image
This menu option will allow the image to be saved as a transparent Gif image.

Reset View
Selecting Reset View will restore the default rotation and scale settings to the pallet.

Appendix C – Reader Control Panel

RFID Readers are used throughout the Instant EPC Hotspot pplication.
The controls for the RFID readers are always on display at the bottom of the screen, and are collectively known as the Reader Control Panel.

Some of the operations of Instant EPC Hotspot do not require RFID reader control. In these instances the reader control panel is grayed out. When an operation does required reader interaction, the controls are all enabled and are displayed in color.

This control panel lets the user set up some basic configuration parameters for the reader, such as the preferred antenna to use and the tag class to read.

The RFID control panel is shown below in figure C.1

The control panel is split into five sections:

Antenna Selection
The antenna settings allow the user to select the antennas to use. For case level testing, just one antenna should be used.
For pallet level testing, multiple antennas should be used to maximize performance.
To toggle an antenna on or off, just click on it. Grey means off, Green means on.

Tag Class
Tag Class determines the type of tag to read. Some readers are single-protocol devices that will only read one type of tag. Other readers are multi-protocol devices that read a number of tags.

Multi-protocol readers often perform better if they spend their entire time looking for one type of tag only. When testing pallets comprising one tag type only, it is recommended to switch to reading one tag type only for best results.

Icons represent the available tag types that the current reader can handle. Common icons are C0 for Class 0 tags, C1 for Class 1 tags and G2 for Gen 2 tags.

The reading of different tag classes can be toggled on or off by clicking on the tag icons. Orange tags mean that the reader is looking for tags of that class. Grey means the feature is turned off.

Attenuation
Attenuation refers to the reduction in power used by a reader. Most readers have the ability to control this feature via software, and it is an integral part of tag location testing.

For most options within Instant EPC Hotspot the operator will not use attenuation. However be aware of the settings. Sometimes tags to do not read even though you expect them to: check the attenuation is set suitably before investigating further.

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