Frequency input seems to be filtered instead of raw on an MC43. How does the MC43 Frequency input filtering work? Is the input filtered over x milliseconds? Is it filtered over x impulses?

Andrew Slaght 12 months ago in IQANdesign updated by Gustav Widén (System support) 12 months ago 4

How does a frequency input of the IQAN module work? i.e.:

a) Filtered over x milliseconds

b) Filtered over x impulses

c) Resolution 1 rpm = x digits


The MC4x and XC4x frequency inputs are based on period time measurement between positive and negative flank. 

It performs one period time measurement for each application cycle. 

Image 3608

Thank you for your response Gustav.  Is the period time measurement just an average of the frequency measured during one application cycle time?

Thank you for your response Gustav. Is the period time measurement just an average of the frequency measured during one application cycle time?

It is measuring frequency by counting the time between flanks. 

As an example, 2.5 ms period time gives the frequency is 400 Hz. 

The FIN channel value is updated to the latest measurement each cycle.