Sorting out the RFID tag debate: read-only or read/write? Weigh all the elements carefully to get the right results

Frontline Solutions, Dec, 2003 by Tom Kevan

If you've decided--or had someone decide for you--to implement RFID tags in your supply chain, the fun is just beginning. Now you have to decide what kind of tag to use--read only or read/write?

You start the decision-making process by asking some basic questions. Is the license-plate model sufficient to meet your application needs? Or, as Dan Bodnar, director of product marketing for data capture systems, Intermec Technologies Corp., asks: "Will the RFID tag ever need to be updated or reused as the asset proceeds through your process and supply chain?"

To answer these questions, you have to look at your application and the strengths and weakness of each type of tag. "Each approach offers advantages and disadvantages that must be evaluated in the context of the application's requirements," says a Matrics white paper titled "Read Only vs. Read/Write RFID Tags."

Read-only tags

According to the Matrics white paper, read-only tags cost less than read/write tags, and the infrastructure required to support read-only is also less expensive.

But Dan Mullen, president of AIM Global, offers another perspective. "Looking at costs of individual components (e.g., tags, readers and infrastructure) is not the right approach. Look at what you want to accomplish, consider what components will be needed, and research costs (the investment in capital equipment as well as the changes being made to your processes and their impact). With all this in mind, consider the ROI that will be received. ROI can be efficiencies gained, or it can be adding value to your operation that makes your products and services mor attractive."

That said, the read-only tags still deliver on one of the main promises of RFID--reduced operator involvement. This translates into lower operating costs and minimal impact on employee work processes and job functions.

Another factor to consider is the use of centralized enterprise IT and database systems. "The surrounding systems, relational databases and enterprisewide IT have progressed very quickly. End users have invested heavily in centralized databases to manage their operations," says Matrics. Read-only RFID tags can simply leverage this centralized approach. The down side of the read-only tag is obvious: You cannot add or modify data on the tag. The very simplicity that makes this type of tag low impact also makes it inflexible.

Read/write tags

Read/write tags are dynamic data carriers, which means that companies can add or change the data on the tag. According to an Intermec report titled "The Write Stuff: Understanding the Value of Read/ Write RFID Functionality," this provides flexibility that lets companies accommodate changes in business processes and customer requirements, allowing them to adapt to evolving application needs and to preserve their initial technology investment.

Because they store data locally, read/write tags can respond quickly to changing conditions in the supply chain. "Read/write tags can have more information stored locally on the tag, which enables faster processing, reduces data latency and may not require a database lookup or any contact with an external system," says Intermec.

Local data storage also means that read/write tags avoid database dependence, which can be "a major hindrance in high-volume, multicompany supply chain applications," says Intermec. "Manufacturers, raw material suppliers, logistics providers and retailers all need access to the same database to optimize their supply chain interactions. This scenario leads to questions and possible disputes over who owns the database, where it should reside, the maintenance responsibilities of each participant, security and access privileges and synchronization issues."

But "read/write is especially valuable for supply chain applications where each trading partner may refer to the same identification information on the tag but also write to and utilize other fields to support their own specific applications and business requirements," says Intermec.

While all these features are impressive, read/write tags do have a number of drawbacks. For example, by using the write process, a company increases operator involvement and the chance of introducing operator errors, which adds a level of complexity.

Also, read/write tags can create constraints in the data capture process. "Most systems require that you write data to a tag at half the read range that you can read the tag. So an item that needs to be programmed or written to, rather than just read, needs to be much closer to the stationary reader. Close proximity of the reader to the tag is a constraint in many situations," says Matrics.

In addition, the write process can take longer than the read process, which can cause delays.

Weighing strengths and weaknesses

"When considering an RFID system, there are many things you need to take into account. Many of these require a detailed knowledge of the options available to make an informed decision," says Michael Liard, senior AIDC/RFID analyst at Venture Development Corp.