7 General Description of Functions
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Energy consumption measurement:
The ejector determines the electrical energy consumed during a suction cycle, including the energy it con-
sumes itself and the energy consumed by the valve coils.
To determine the values for the air consumption as a percentage and the electrical energy consumption,
the neutral phase of the suction cycle must also be taken into account. Therefore, the measured values
can only ever be updated when the next suction cycle begins. Throughout the cycle, the measured values
displayed then represent the results from the previous cycle.
7.24.3Predictive Maintenance (PM)
For early detection of wear and other impairments to the vacuum gripper system, the ejector features
functions for detecting trends in the quality and performance of the system. The leakage and dynamic
pressure are measured for this purpose.
Measurement of leakage:
The leakage (represented as the vacuum drop per time unit in mbar/s) after the control function inter-
rupts suction because the vacuum limit value H1 has been reached is measured.
The measured value for the leakage rate and the related quality assessment in percent are reset at the
start of every suction cycle and constantly updated during the cycle as moving averages. The values there-
fore remain stable until after the suction cycle is complete.
Measurement of dynamic pressure:
This measures the system vacuum achieved during unobstructed suction. The duration of the measure-
ment is approx. 1 second. Therefore, to evaluate a valid dynamic pressure, uninterrupted suction is re-
quired for at least 1 second after starting the suction, i.e. the suction point must not be covered by a part.
Measured values below 5mbar or above the vacuum limit value H1 are not regarded as valid dynamic
pressure measurements and are rejected. The result of the last valid measurement is retained. Measured
values that are higher than the vacuum limit value (H2-h2) and simultaneously lower than vacuum limit
value H1 result in a condition monitoring event.
The dynamic pressure (vacuum during unobstructed suction) and the related performance assessment in
percent are initially unknown when the ejector is switched on. As soon as a dynamic pressure measure-
ment can be performed, they are updated and retain their values until the next dynamic pressure mea-
surement.
Quality assessment:
To evaluate the overall gripping system, the ejector calculates a quality rating based on the measured sys-
tem leakage. The greater the leakage in the system, the worse the quality rating of the gripping system.
Conversely, low leakage results in a high quality rating.
Performance calculation:
Similar to the quality assessment, the performance calculation is used to evaluate the system status. The
performance of the gripping system can be assessed based on the determined dynamic pressure. Opti-
mally configured gripping systems lead to low dynamic pressure and thus to high performance. Con-
versely, poorly configured systems result in low performance. Dynamic pressure events that exceed the
vacuum limit value (H2-h2) always result in a performance rating of 0%. A dynamic pressure value of
0mbar (indicator that a valid measurement was not obtained) also results in a performance rating of 0%.
7.24.4Diagnostic Buffer
The condition monitoring warnings described above and the general error messages from the device are
saved in an integrated diagnostic buffer. The content of this memory is made up of the last 38 events,
starting with the most recent, and can be read out via an IO-Link parameter. For each event, the current
reading of the suction cycle counter cc1 is also saved to allow subsequent temporal assignment of the
events to other processes in the system. See the associated IO-Link Data Dictionary for the actual data dis-
play of the diagnostic buffer. The recording of these events is also active in SIO mode and the contents of
the memory is retained after a power failure.
The memory is deleted manually using the IO-Link system command “Clear diagnostic buffer” or also by
restoring the factory settings on the device.
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