Rockwell Automation 6000 Industrial Computers Technical Reference Guide - Manual (Page 7)

SAW Touchscreen
“Surface Acoustic Wave”. This touchscreen technology uses an overlay material with
micro channels that carry sound waves across the display surface. When touched, the
sound waves are disrupted and the touch position is decoded by the interface electronics.
The advantages of SAW touchscreens are increased display brightness with only a single
overlay sheet, and easy to panel seal for NEMA4 applications. The disadvantages of
SAW touchscreens are limited touch resolution and sensitivity to false activation from
surface dirt, water, and debris.
Reliability Information
Calculated MTBF
Mean-Time-Before-Failure calculations are not an accurate representation of an industrial
computer or monitor product’s expected life cycle in a factory environment. Commercial
high technology suppliers change their products so rapidly that very little statistical
information available for realistic MTBF estimates. It is also a highly competitive
market, so calculated MTBF numbers are often highly overstated. For example, some
hard drive manufacturers claim up to 1 million hours MTBF. While this may be
theoretically possible in a laboratory environment, most hard drives will not last 100
years in everyday operation. Because of the inaccuracy and variability involved with
calculated MTBF numbers, Allen-Bradley does not promote the use of calculated MTBF
for product comparisons, unless the calculations are performed with the same
methodology and input criteria.
Demonstrated MTBF
A more accurate means to gauge a product’s reliability is through accelerated life testing.
This demonstrated MTBF method provides a more realistic gauge for the product’s
expected MTBF. Allen-Bradley performs demonstrated MTBF testing on its 6180 and
6181 computer products. The 6180 testing has been ongoing for over 4 years, and has
achieved in excess of 75,000 hours “demonstrated MTBF”. The 6181 testing was started
in August 1999.
Other Reliability Factors
All RAC6000 flat panel computer and monitor products have LCD panels with CCT
backlights. The backlight tubes are rated in terms of time to half brightness. So if a
product’s backlight states 50,000 MTBF, that means 50,000 hours until the backlight
tubes are half as bright as when they were new. Allen-Bradley RAC6000 products use
the highest quality displays available, and try to maximum the backlight tube life to
reduce customer downtime. All RAC6000 backlight tubes are field replaceable.
RAC6000 Product Support
All RAC6000 computer and monitor products are built-to-order. As a result, it is not
economical or logistically feasible to provide a repair parts inventory of finished products
for exchange. All RAC6000 products are modularly designed for field replacement of
component items. Because of the variability of computer components, some items may