Attributes and Limitations
|Read/write, electronic storage technology|
|Low to relatively high data storage capability|
|Direct contact read systems|
|Relatively low cost tags, programming and read facilities|
|Data transfer rate determined by systems and serial interface|
|Robust tags suitable for relatively harsh environments|
|Relatively small application base|
A contact memory device looks like a small button-style camera battery, but it's really a stainless steel container with a memory chip sealed inside. The top of the button is bonded to one point in the memory circuit; the bottom and sides of the package provide a signal ground. Data is written to and from the button using a probe-like device that is touched to the two electrical points on the unit, thereby establishing a communication path. A button can act as a "license plate" identifier or as a portable database in which data can be read and modified.
The buttons generally come with a unique pre-programmed identification number and are available in a variety of memory configurations. They can hold up to four million bytes of reprogrammable data, including text, pictures, and even voice messages. This data may be transferred to a computer via a button reader at speeds up to 16.6 Kbps. Buttons may be set with a password to protect the data from being read or rewritten.
Some buttons are powered by small internal batteries that guarantee data retention for 10 years from date of manufacture. Other battery-free designs retain data up to 100 years, and each time the button is read, a small amount of additional power is transmitted to it, further extending its memory. Buttons are sealed to withstand moisture, radiation, and temperature extremes, and operate under a wide range of temperatures.
Contact memory technology will continue to be employed in cutting edge applications ranging from electronic purses, research, and electronic product identification, to collecting oil production data in the field. Users (and manufacturers) will combine buttons with other technologies in creative ways to enhance their AIDC applications. For example, one type of button incorporates a digital thermometer that can measure temperatures from -55 ºC to +100 ºC, typically in one second. Users can place these sensors to obtain a temperature profile of a piece of equipment, a room, or a building. Touch/button memory is a relatively simple AIDC method whose use is limited only by a user's inventiveness.