Choosing RFID For Industrial Applications; Part 3


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In part one and two of this blog series, I provided an introduction to the 3 most common frequencies/systems used in industrial RFID and detailed Low Frequency (LF) based systems. In this post, I will provide more details specifically about HF or High Frequency based RFID.

High Frequency

Image 3, High frequency Balluff tag samples

HF RFID systems typically operate at 13.56 MHz. These systems are usually based on either the ISO 14443 (also known as the Mifare standard) or the ISO 15693 standard. The benefits to these standards are that they can allow interoperability between several manufacturers of tags (see image 3) and read/write hardware, though both standards allow the user to openly read the tags’ unique serial numbers. Typically, most 14443 based tags have the user data memory password protected, ensuring that the user data can only be read by the manufacturer’s hardware. Most of the time, the password is not accessible to the user.

Because of this standardization and commonality of hardware like tag transceivers, HF based systems also provide lower cost for the user than proprietary systems and can be comparable in cost to LF tags. HF systems are also generally station based like LF systems, where tag data is read and/or written at a specific “check” point in a process.

Unlike the LF based tags, HF tags typically see significant read/write signal degradation when mounted in a metal alloy, thus limiting range unless designed specifically for this purpose. HF read/write ranges can also be degredated by having metal in or near the field created by the head. There are exceptions where some manufacturers have created special tag and head antenna designs allowing minimal effects from metal. These special tags and heads can use techniques like “rod” style antennas instead of coil antennas.

Image 4, “Near field” inductive coupling antenna example

HF systems also have good range, as much as 150mm or more when mounted on non-metal surfaces. The range for HF tags mounted on or in metal is usually manufacturer specific. Because of the nature of their higher transmission speeds, HF systems can read/write tag data considerably faster then LF systems. For example, to read a block of 16 bytes or 128 bits of data, a read process can be completed in 30 milliseconds or less. To write the same 16 bytes of data can typically be completed in 60 milliseconds or less.

HF tags are also available in two memory types, EEPROM with 800 bytes or less of user data memory capacity (like LF tags) or FRAM type. FRAM (Ferroelectric Random Access Memory) typically offers high memory capacity – 2K bytes or more and is not limited in write cycles making it capable of essentially unlimited read and write operations. Because of their higher read/write speeds, HF systems can be used for applications that require continuous movement at speeds of 3 meters per second or more, depending on the amount of data being transferred.

Because both LF and HF RFID systems operate on the principle of inductive coupling (see image 4), they operate in what’s known as “near field”. This means that these systems are less susceptible to interference from other adjacent systems and minimal distances are required between read/write heads compared to other RFID system types.

In the next blog post of this series, I will continue to define in more detail the last of the three frequency/system types introduced in the first series post, moving finally to UHF or Ultra High Frequency.

Click here to learn more about Balluff industrial RFID.
Click hereto read a whitepaper on “Choosing RFID For Industrial Applications”.

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One Response

  1. ISO14443 is not known as the Mifare standard. In fact it (Mifare) is not fully compliant to ISO14443A at all.

    I also read the LF blog you put up as well. There are some misunderstandings you have about LF – specifically the way it works, etc.

    be glad to help you understand this better.

    best regards –
    Josh
    josh.wyatt@ti.com
    214-567-5124

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