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 EL3356 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).