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Be sure to design the control system so that,
in the event of a power failure or a display unit accident, the
user system's overall safety integrity will be maintained. If this
is not done, incorrect output signals or a display unit malfunction
may cause an accident.
(1) Emergency stops, safety circuits,
interlocks that operate with opposing actions such as
clockwise/counterclockwise rotation, and interlocks that prevent
machine damage with upper, bottom, movement, and other limits,
should be designed outside the display unit.
(2) When the display unit generates a Watchdog
Timer Error during logic program operation, the logic program
operation will halt. Also, when errors occur in Input/Output
control areas that the display unit cannot detect, unanticipated
operations may occur. Therefore, and to prevent unsafe machine
movement, a Failsafe Circuit should be created which is completely
external to the display unit.
For a failsafe circuit, please refer to the
hardware manual section titled "Installation Precautions".
(3) If a problem arises with an external unit's
relay or transistor, causing an output (coil) to remain either ON
or OFF, a major accident can occur. to prevent this, be sure to set
up external watchdog circuits that will monitor vital output
signals.
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Design a logic program with interlock circuits
that ensure the safety of the system in the event of a display or
control error, a data transmission error, or power failure between
the display unit and connected units. If this is not done,
incorrect output signals or a display unit malfunction may cause an
accident.
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Do not use display units with aircraft control
devices, aerospace equipment, central trunk data transmission
(communication) devices, nuclear power control devices, or medical
life support equipment, due to their inherent requirement for
extremely high levels of safety and reliability. Do not use for
these purposes.
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When using the display unit with transportation
vehicles (trains, cars, and ships), disaster and crime prevention
devices, various types of safety equipment, and medical devices
that are not life-support related, use redundant and/or failsafe
system designs to ensure proper reliability and safety.
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After the display unit's backlight burns out,
the touch panel is still active. This is unlike the display unit's
Standby Mode. If the operator fails to notice that the backlight is
burned out and touches the panel, a potentially dangerous machine
operation error can occur. Therefore, do not create touch panel
switches that may cause injury and/or equipment damage.
If the display unit backlight is OFF, use the
following to determine if the backlight is burned out.
(1) If the screen has gone blank although the
display unit is not set up to enter Standby Mode, then the
backlight is burned out.
(2) If screen has gone blank and the display
unit is set up to enter Standby Mode, touch the screen or perform
some other input operation. If the screen does not reappear, the
backlight is burned out.
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