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4. Technical specificationsFunctional safety engineering
Festo.P.BE-CMMS-ST-HW-EN 0903b
79
Explanations on the circuitry example
The circuitry example shows a combination of the CMMS-ST with a PILZ PNOZ X2P safety
switch device. The auxiliary contactor K2 (with forced contacts) ensures that the
intermediate circuit is not connected directly over the normally open contact of the PNOZ.
This protects the normally open contact of the PNOZ device. Technical specifications, such
as max. current, etc. can be found in the data sheet of the safety switch device.
EMERGENCY-STOP request, monitoring of protective door
After the Emergency Stop button is actuated or the protective door is opened, the two
normally open contacts of K1(13, 14 and 23, 24) open immediately. This results in the
immediate removal of the end-stage enable and deactivation of the auxiliary contactor. As
a result, there is a two-channel switch-off. The unintended opening of the protective door
must be prevented in the system.
The controller state accordingly depends on the programmed error reaction for the error
020 (undervoltage in intermediate circuit).
Due to the described wiring, a two-channel operation with cross-circuiting recognition is
possible. This permits recognition of:
Earth faults in the start and initial circuit
Short circuits in the initial circuit / start circuit
Cross circuits in the initial circuit.
Removal of the end-stage enable and switching off the intermediate circuit voltage causes
the drive to run out.
Restoration of normal operation
Before switching it on again, make sure that all hazards have been eliminated and the
equipment can be safely placed in operation again. If there are areas inside that can be
entered, a manual acknowledgement must be made via the optional S2 button.
Testing the safety function
For each on-off cycle of the machine, the PILZ device PNOZ X2P checks whether the relays
of the safety equipment open and close properly.
The function of switching off the end stage enable must be checked regularly (e.g.
monthly) via the PLC.
4.3
SS1, Safe Stop 1
Explanation
In the function "Safe Stop 1" (SS1), the drive is run down in a controlled way and, after
that, the power supply to the final output stage is switched off.
As a result, the drive
cannot generate torque or any force at standstill and so cannot make any dangerous
movements.