Enabling Button - Siemens SIMATIC HMI Mobile Panel 277 RO Operating Instructions Manual

Safety instructions and general notes

2.7 Enabling button

2.7 Enabling button
Introduction
The enabling control device comprises the two enabling buttons mounted on both sides of
the Mobile Panel 277 RO.
Numerically controlled machines and systems are equipped with the operating modes
"Automatic mode" and "Special operation".
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 operation, safety has to be ensured in a different manner than in automatic mode.
In special operation mode, the danger zones of the machine or system are entered, where
controlled movements have to be possible.
Special operation
A reduced speed on the machine or in the system has to be specified for special operation
based on the risk assessment. An action must be possible only when the enabling control
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 control
device are designed in such a way that they satisfy the EN ISO 13849-1:2008/AC:2009
category determined by the risk assessment.
The enabling buttons meet the requirements of Category 3 PL d in accordance with
EN ISO 13849-1:2008/AC:2009 when used in combination with an external monitoring
device.
Category 3 in accordance with EN ISO 13849-1:2008/AC:2009 can be achieved by
implementing the enabling control device with 2 circuits and suitable monitoring for shorting
and crossing of these circuits.
The draft C standard for machine tools notes the following: "Enabling devices can either be a
2-position command device in conjunction with a Stop device or a 3-position command
device. The 3-position command device is preferable."
The operating principle of an enabling control device is described in EN 60204-1:2006.
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.
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Operating Instructions, 10/2015, A5E36824256-AA
Mobile Panel 277 RO