Beckhoff EP3356-0022 Documentation page 79

Idling recognition
Weighing is a dynamic procedure that can lead to large jumps in the bridge voltage and thus to the
calculation of the value. Following a change in load, the measured value must first "settle" so that the
process value is evaluable in the controller. The evaluation of the measured value and the decision over the
degree of calmness can be done in the controller; however, the EL/EP3356 also offers this function, which is
activated by default. The result is output in the status word.
• If the load value remains within a range of values y for longer than time x, then the SteadyState is
activated in the StatusWord.
• SteadyState is set to FALSE as soon as this condition no longer applies.
• The parameters x and y can be specified in the CoE
• The evaluation is naturally considerably affected by the filter setting
In the following example (recorded with TwinCAT Scope2), a 15 kg load cell is suddenly unloaded and
loaded with 547 g. SteadyState is subject to a window time from 100 ms and a tolerance of 8 g (15 kg
nominal value, scaling 1000; see CoE).
Fig. 75: Load cell loaded and unloaded
Official calibration capability
"Official calibration" is a special kind of calibration that is accomplished according to special regulations with
the involvement of trained personnel using prescribed aids. The use of "officially calibrated" scales is
mandatory in the Central European region, in particular for the filling of foodstuffs. This ensures the
correctness of the weighed quantities in a particular way.
The Beckhoff EL/KL335x terminals and the EP3356 boxes cannot be officially calibrated as individual
devices. However, they can be integrated as elements in applications that can then be equipped by the
integrator with the required characteristics for official calibration capability using appropriate means.
EP3356-0022 Version: 1.1.0
Commissioning/Configuration
79