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Safety instructions and standards
2.7 Safety functions of the enabling mechanism
Note
The EMERGENCY STOP button is evaluated when the HMI device is integrated in the
safety program of the F-CPU. The EMERGENCY STOP button can be triggered
unintentionally in the following situations:
If the HMI device falls down
When opening one of the coverings on the rear of the HMI device
2.7
Safety functions of the enabling mechanism
In a numerically controlled system, the "Special mode" operating mode requires an enabling
mechanism. The enabling mechanism is comprised of two enabling buttons mounted on both
sides of the HMI device.
Special mode
During special mode, safety has to be ensured in a different manner than in automatic mode.
During special mode, personnel enter danger zones of the plant in which controlled
movements must be possible.
Depending on the risk assessment of the plant, movement needs to occur at reduced speed
for special mode. Movement of the plant parts should only be possible when the enabling
mechanism is activated. The operator must be accordingly qualified and know details of use
in accordance with safety regulations.
Safety instructions
The safety-related parts of the controller for speed reduction and those for the enabling
mechanism are designed in such a way that they satisfy the requirements for the safety
category as determined by the risk assessment.
The operating principles of enabling devices are described in EN 60204. Through the
findings from accident investigations and the existence of technical solutions, the 3-stage
enabling button became state of the art. Positions 1 and 3 of the enabling button are Off
functions. Only the middle position allows the enabling function. EN 60204-1 is identical to
IEC 60204-1, whereby the 3-stage enabling button is gaining international importance.
42
PRELIMINARY II
Wireless Teach Pendant F IWLAN V2
Operating Instructions, 08/2010, A5E02453837-01
1.7.2010
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