We need to do a self-check firstly:

- we use the demo software,connect UHF readers.and then click “set parameter”

- we can take UHF reader to another more empty place to test,avoiding signal interface

- pay attention to the installment angle for UHF reader

- check if there is other things covered on cards or labels

- check if this UHF cards or tags aging or not

- Check if your UHF cards are from us or not.and if they are EPC GEN2 ISO18000-6C

Please ask sales the profile ‘deal the same number for WG data’

If so,we can try USB to RS232 converter.Or use RS485 interface.

ISO 18000-6 is an international standard governing the way tags and readers communicate in the UHF spectrum. 

There are currently three versions: 18000-6A, 18000-6B and 18000-6C. Of these, 18000-6C is by far the most commonly used.

EPC Gen 2 was designed to work internationally and has other enhancements that are significant, 

but the real benefit of Gen 2 is that it works anywhere in the world and major manufacturers of chips and tags have lined up behind it.

The answer to these questions is that just about any asset, part, product or other item can be identified, tracked and managed using 

an ultrahigh-frequency RFID tag. But tagging methods vary, based on an item's shape, size, material and texture, 

as well as the environmental conditions in which it will be tracked.Among the key issues that must be considered, as below:

• the size of the asset to be tagged and the footprint available to receive the tag

• the surface of the asset to be tagged, such as metal, plastic, cloth, living tissue (nursery stock, farm livestock, lab animal, 

   pets, infants), wet paint, wet chemical coating, chemically treated, abrasive

• the duration of time the asset needs to be tagged—short or long term, permanent or temporary

• the duration of time the item will be exposed to environmental conditions, such as extreme temperatures, moisture, 

  chemicals, abrasion, dust, human contact, pressure, salt water, animal exposure, outdoor ultraviolet exposure and weather conditions, 

  industrial processing, temperature shock (going from hot to cold and back), flash freezing (dry ice), and lab testing

• the asset's temperature at the time of tagging; for example, hot molded products just out of the mold, or frozen consumer vending products

The distance from which a tag can be read is called its read range. Read range depends on a number of factors, including the frequency of the radio waves uses for tag-reader communication, the size of the tag antenna, the power output of the reader, and whether the tags have a battery to broadcast a signal or gather energy from a reader and merely reflect a weak signal back to the reader. Battery-powered tags typically have a read range of 300 feet (100 meters). These are the kinds of tags used in toll collection systems. High-frequency tags, which are often used in smart cards, have a read range of three feet or less. UHF tags-the kind used on pallets and cases of goods in the supply chain-have a read range of 20 to 30 feet under ideal conditions. If the tags are attached to products with water or metal, the read range can be significantly less. If the size of the UHF antenna is reduced, that will also dramatically reduce the read range. Increasing the power output could increase the range, but most governments restrict the output of readers so that they don't interfere with other RF devices, such as cordless phones.

This is a mode of operation that prevents EPC Gen 2-compliant readers from interfering with 

one another when many are used in close proximity to one another. Readers hop between channels 

within a certain frequency spectrum (in the United States, they can hop between 902 MHz and 928 MHz) 

and may be required to listen for a signal before using a channel. If they "hear" another reader using that channel, 

they go to another channel to avoid interfering with the reader on that channel.

Active RFID tags have a battery, which is used to run the microchip's circuitry and to broadcast a signal to a reader 

(the way a cell phone transmits signals to a base station). Passive tags have no battery. Instead, they draw power from the reader, 

which sends out electromagnetic waves that induce a current in the tag's antenna. Semi-passive tags use a battery to run the chip's circuitry, 

but communicate by drawing power from the reader. Active and semi-passive tags are useful for tracking high-value goods 

that need to be scanned over long ranges, such as railway cars on a track, but they cost a dollar or more, 

making them too expensive to put on low-cost items. Companies are focusing on passive UHF tags, 

which cost under a 50 cents today in volumes of 1 million tags or more. Their read range isn't as far -- typcially less than 20 feet vs. 

100 feet or more for active tags -- but they are far less expensive than active tags and can be disposed of with the product packaging