RFID introduction and usage

By attaching RFID transponders/tags to equipment, the unique identification can be read digital by using a suitable RFID reader. This is much faster and gives a more accurate result than typing numbers on a keyboard. Onix applications such as Onix Tag, Onix Tool Store, Onix Worker, and Onix Inspect support RFID as a quick way to identify the unique equipment.

General

Standard: UHF with EPC Class 1 Gen 2 ISO 18000-6C.
Operating frequency: Global 860–960 MHz, EU 860-865 MHz

Read distance Optimal Size Usage
High-performance >70 cm 80-120 mm Large stores
Medium-performance >30 cm 25-60 mm Smaller stores/Inspection
Low-performance >1 cm 6-12 mm Inspection

RFID readers

We have mainly five categories of readers:

  1. Gate reader
  2. Desktop reader
  3. Pocket reader
  4. Handheld readers
  5. Fixed readers

(Onix make use of 1 - 3, but support for 4 is on its way)

These are divided into two groups of antennas:

  • Linear polarization
  • Circular polarization

Gate reader

For the gate to perform optimal, both antenna and tags must be tuned to fit the environment.
For the antenna/gate, we can adjust the power.
For the tags, we must choose the optimal size for the purpose.

The main rule is that larger tags give longer reading distance.
The gate’s antennas are powerful. They can easily pick up a high-performance tag at 5-15 meters.

Consider:

a) We have a small store with 99 small tags and 1 large tag. If we turn the gate’s effect to maximum to get a steady signal for the smaller tags, it is a high risk that the single large one will be picked up for every read if it is located closer than 10 meters.
b) We have a store with 99 large tags and 1 small tag. If we lower the effect to prevent reading nearby tags unintentionally, it is a high risk that the single small one can never be read.
Therefore, we need all tags to have the approximately same effect.

Gate readers mainly use circular polarized antennas.

image

Left: High antenna effect: High read efficiency in the gate area. Large tags in the field/store might be read unintentionally.
Right: Low antenna effect: Minimal chance of unintentional reads. Small tags might not be picked up in the gate area.

Desktop reader

Desktop readers normally have a limited reading field, but capable of reading everything from low-performance tags to high-performance-tags.
Since the antenna area/surface often is exposed, it is naturally to place the tag near this field.

Therefore low-performance tags are suitable for desktop readers, even though smaller tags often require direct contact between the reader’s surface and the tag.
Medium-performance tags can typical be read from 50-100 mm and high-performance tags up to 1 meter. Some high-performance tags will however be read from distances up to several meters.

Blue lines: antenna-field
Green lines: tag-field

The more lines that cross, the higher possibility of a confirmed read.

Onix has support for linear polarized desktop readers.

Pocket reader

Pocket readers are designed to be small and therefore with a small antenna surface.
As for desktop readers, the antenna area/surface is exposed, and suitable for low-performance tags even though some might be difficult to read and requires direct contact between antenna and tag.

Pocket readers are often connected by blue tooth (wireless connection). Since RFID consumes a relatively high amount of power, it is designed to power off after a given time. The reader must be reconnected with the application after turning it back on again. For handheld devices not supporting USB/wired connection, this is the preferred reader.

Most pocket readers are linear polarized.

image
Blue lines: antenna-field
Green lines: tag-field

The more lines that cross, the higher possibility of a confirmed read.

Handheld reader

Handheld readers are normally divided into two groups:

  • With operative system (E.g. Windows CE or Android)
  • Connected to computer with wire, or wireless

Handheld readers can use both linear and circular polarized antennas.
(Onix does per date not support this category of readers)

Fixed reader

Fixed readers can often be read as wall mounted readers.
If two or more readers are connected, they can have much the same function as a gate reader.

Fixed readers often have circular polarized antennas.
(Onix does per date not support this category of readers)

Linear polarized antenna

For the linear polarized antenna to work, the tag must be held parallel to the reader’s antenna.
Since the signal is directed in one level (horizontal or vertical), it can carry for a long distance.

Circular polarized antenna

Circular polarized antennas will consume more power to carry the signal.
This is because it is designed to pick up a signal regardless if the tag is placed horizontal or vertical in the field. It is still important that the tag faces the reader.

RFID Tags

We have mainly three categories of tags:

  • Metal tags use the connected surface as an antenna and can be smaller without losing effect. If they are connected to surfaces other than metal, they will also loose most of the effect.
  • Standard tags. These often have a very strong signal due to size, but metal will absorb the signal and make them unreadable.
  • Some tags can be mounted on all materials. They have a built-in shield against the surface. This shield will often make the tag a bit thicker than other tags. They also need to be larger, since the shield will have some negative effect on the signal.

image
Left: Metal tag on metal: Boosted directional performance
Right: Metal tag on e.g. plastic: Poor performance

image

Left: Standard tag on metal: Poor performance
Right: Standard tag on e.g. plastic: Good performance

image
Left: All surface tag on metal: Medium directional performance
Right: All surface on e.g. plastic: Medium performance

Unfortunately, all categories have their up- and down-sides. None of them are perfect for overall usage.

Our recommendation:

Use tags meant for metal whenever it can be connected to a clean metal surface.
Use standard tags for other surfaces.
If the size of the surface allows it, consider tags meant for all materials.

Recommended usage for Onix products

Onix Tool Store

Use desktop reader:

Since the signal often is limited, the tagged equipment must be hold close to the reader.
Try to keep the reader in a fixed position. Move the tagged object into position, not the reader.
Place the reader where it can be conveniently reached from all heights. Large objects might not be easy to place on a table.

Onix Tag

Use desktop reader.

Since the signal often is limited, the tagged equipment must be hold close to the reader.
Try to keep the reader in a fixed position. Move the tagged object into position, not the reader.
Place the reader where it can be conveniently reached from all heights. Large objects might not be easy to place on a table.

Onix Inspect

Use pocket reader.

For the Windows version, use wired connection.
For the Android/iOS version use Bluetooth connection.

Since the signal is relatively week, locate the readers antenna position.
Place the tag as close as possible to this point for best result.

Sample tags and readers

Sample tags, medium-performance

Sample tags, low-performance

image

Sample readers (UHF 865-868 MHz)