How to test RFID IoT devices for enterprise deployment

Legacy manual and barcode systems are still in widespread use, but many organizations are turning to the internet of things, specifically RFID tags, to streamline asset tracking in the data center.

It’s important to test these devices before deploying, and this article addresses typical testing considerations for this type of device deployed in a networked environment, ranging from data center asset tracking, inventory management and warehouse operations to scientific labs and medical facilities.

RFID types

RFID-tags can be scanned manually using a handheld scanner and passive tags, or by using active tags and fixed readers/antennas. Active devices typically have a built-in power source whereas passive devices do not. Passive RFID tags provide information only when interrogated by a reader; active tags broadcast information that can be picked up by a reader.

As the name implies, RFID devices use radio frequencies to communicate. The coverage area of an RFID device ranges from just a few inches to several hundred feet. Since active tags have an internal power source, they have stronger signals that can overcome some interference from surrounding electromagnetic fields. The benefits of passive tags include lower cost and longer life spans.

RFID devices operate across a wide spectrum from low frequency (125 KHz) to microwave (10 GHz).

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RFID components

A typical RFID system consists of tags, readers, antennas, printers, and software. A typical RFID tag has a tiny integrated chip, an antenna and some form of encasement. Active tags have some form of power source, such as an internal battery. Tags are available in a variety of formats such as hard tags, flexible, badges, cards, wristbands, key fobs, labels, tickets and inlays, which are semi-finished tags that can be converted into all of the above and other applications.

RFID tags are either read-only or read/write, depending on the purpose of the tag. Some are preprogrammed, or they can be programmed in the field.

RFID readers are either handheld or fixed. A handheld reader is used for manually reading tags, as when walking through a data center and manually scanning hardware assets. Fixed readers are used for applications where the tags are passing by the reader, for instance with ID cards used to access a data center or items being scanned while going down a conveyor belt.

RFID antennas are often classified for near or far field use. Near field is generally defined as less than 15 inches, whereas far field antennas can read from a much great range, from just an inch to many feet. In addition, RFID antennas are grouped into three different categories having to do with polarization and other attributes. It is important to research and test to find the best antenna for your application.

Many tags can be purchased ready programmed with sequential IDs, but you can also print your own with a label printer. It’s essentially a thermal printer that prints a label with human-readable information while encoding information onto the chip embedded within the label.

Another important part of RFID installations is software that supports communication with the tags. There are many vendors that provide off-the-shelf applications for this purpose, often as part of an RFID package solution. Another option is to connect directly to your own infrastructure, either through a middleware application or using drivers that connect to existing backend data repository.

RFID testing considerations

For starters, it’s important to set realistic expectations. In most scenarios with currently available technology, it is unrealistic to expect that you can read every RFID tag in the building in one operation. That is true of both static tags affixed to assets like printers and servers, as well as something like a large shipping container containing individual items with tags. In order to achieve 100% read rate, you’re better off reading tags individually or in smaller batches.

When implementing RFID devices, there are a number of important technology-specific tests required to ensure a successful deployment.

Site survey and physical environment

While RFID technology offers appealing advantages over a barcode system, it is more susceptible to the environment where it is deployed. It is important to know where the tags should be placed, how they can easily be scanned and which components are needed to build a complete solution. In order to accomplish this and maximize the benefits of an RFID system, you need to do extensive testing, including a thorough survey of the installation area.

The critically important RFID site survey looks to identify possible sources of interference and provide guidance on RFID reader placement. The site survey also provides information about the operating environment and recommendations on the correct tags and attachment methods for each category. Also, consider using a frequency scanner to check for interference from existing infrastructure, such as equipment racks and other potential signal barriers

When deploying RFID devices into a production environment, it is important to factor in variables such as temperature swings, air flow, and moisture. Make sure the environment will be suitable for the sensor the RFID device uses. Also be sure that personnel applying the tags are properly trained and know where and how to apply the tags. Nightmare scenarios have surfaced in which tags blocked server air flow or tags were improperly secured and fell off after a few days.

For larger installations, it may be advisable to hire a third party to perform the site survey, as they will have the specialized equipment and expertise to ensure a successful deployment.

Read range and reliability

Another important test metric is the read range. With any RFID deployment you want to make sure you consistently achieve as close to 100% read rate as possible. There are numerous potential obstacles to achieving this, including interference from unrelated existing wireless infrastructure or even from too many devices chirping over one another in a high-density environment.

For the basic passive tags, make sure they can be reliably read by the reader when scanned. For more complex systems, such as an access card system or an inventory management system, you need to make sure to test the proximity of the antennas and readers to ensure that the tags can be read. Can the tag be read from different angles?

To test for interference you may want to utilize a frequency hopper to measure the impact other devices may have on your installation.

Radio frequency and other regulatory requirements

When implementing RFID technology, keep in mind that it must pass all applicable regulatory requirements and standards. There are government regulations that specify permissable power, bandwidth and frequency of RFID devices to ensure they don’t interfere with communications at a nearby airport or someone’s medical devices.

Device compatibility

It may seem obvious, but you want to make sure your RFID components are compatible with each other, which will typically require testing in the actual environment where it the RFID devices will be deployed. For a large-scale deployment, a full test may not be feasible in which case you need to set up a test environment that most closely represents the production environment.

Commercial RFID test solutions

A threshold question is whether to commit resources and buy all the equipment needed to test everything yourself or outsource the testing. There are a growing number of commercial RFID test providers, which typically offer proprietary, highly sensitive test equipment. In some cases they will sell you the equipment to use, while others offer a turnkey RFID testing service.

Third-party testing services can also assist with things such as compatibility testing and certification, scalability, usability and reliability assessments, security and data integrity testing. When deciding to use a third-party to assist with one or several aspects of an IoT deployment, it’s advisable to select a company with expertise in the specific field you’re considering. This is especially true when specialized equipment is needed to test the sensors on a particular device.