General safety information and precautions
The following safety precautions are intended as a general guideline for using PLC systems together
with other equipment. These precautions must always be observed in the design, installation and
operation of all control systems.
● Observe all safety and accident prevention regulations applicable to your specific applica-
tion. Always disconnect all power supplies before performing installation and wiring work
or opening any of the assemblies, components and devices.
● Assemblies, components and devices must always be installed in a shockproof housing fitted
with a proper cover and fuses or circuit breakers.
● Devices with a permanent connection to the mains power supply must be integrated in the
building installations with an all-pole disconnection switch and a suitable fuse.
● Check power cables and lines connected to the equipment regularly for breaks and insulation
damage. If cable damage is found immediately disconnect the equipment and the cables
from the power supply and replace the defective cabling.
● Before using the equipment for the first time check that the power supply rating matches that
of the local mains power.
● Take appropriate steps to ensure that cable damage or core breaks in the signal lines cannot
cause undefined states in the equipment.
● You are responsible for taking the necessary precautions to ensure that programs interrupted
by brownouts and power failures can be restarted properly and safely. In particular, you must
ensure that dangerous conditions cannot occur under any circumstances, even for brief
● EMERGENCY OFF facilities conforming to EN 60204/IEC 204 and VDE 0113 must remain fully
operative at all times and in all PLC operating modes. The EMERGENCY OFF facility reset
function must be designed so that it cannot ever cause an uncontrolled or undefined restart.
● You must implement both hardware and software safety precautions to prevent the possibil-
ity of undefined control system states caused by signal line cable or core breaks.
● When using modules always ensure that all electrical and mechanical specifications and
requirements are observed exactly.