Siemens SIMATIC HMI Operating Instructions Manual page 45

Safety is ensured in automatic mode by means of closed, isolating protective devices and/or
with functional non-isolating protective devices that block access.
In special mode, safety has to be ensured in a different manner than in automatic mode. In
special mode, the danger zones of the machine or system are entered, where controlled
movements have to be possible.
Special mode
A reduced speed on the machine or in the system has to be specified for special mode
based on the risk assessment. Movement of the machine should only be possible when the
enabling device is activated. The operator must have the necessary qualifications and be
acquainted with the details of the intended application.
Safety instructions
The safety-related aspects of the velocity reduction control and those for the enabling device
are designed in such a way that they satisfy the EN 954-1 safety category determined by the
risk analysis.
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 60204-1:1997 is
identical to IEC 60204-1, whereby the 3-stage enabling button is gaining international
importance.
The Stop category of the enabling device must be selected on the basis of a risk assessment
and correspond to a Category 0 or 1 Stop.
Injury or material damage
Enabling buttons should only be used when the following applies for the person activating
the enabling button:
• The person can see the danger zone.
• The person is capable of recognizing personal injury hazards in good time.
• The person is capable of taking immediate measures to avoid danger.
The only person allowed to remain in the danger zone is the person who is activating the
enabling button.
Commands for unsafe conditions are not permitted to be issued with one enabling button
alone. For this purpose, a secondary, intentional start command by means of a button on
the Mobile Panel 277F IWLAN is required.
If you leave the effective range only briefly for a time period of up to 30 seconds while the
enabling button is pressed, the following occurs: 5 seconds after the effective range is left,
the enabling function is revoked.
If you enter the effective range again within 30 seconds, the enabling button must be
released and pressed again in order to reactivate enabling.
Mobile Panel 277F IWLAN
Operating Instructions, 12/2007, A5E01003940-01
WARNING
Safety instructions, standards and notes
2.8 Enabling button
45