The Filter function block executes a first-order lag algorithm (a low-pass filter) to filter out high frequency components of the input signal (spikes) and to pass through the low frequency components. The transfer functions for the Filter function block are as follows:
If TIMECONST <> 0:
If TIMECONST = 0:
where:
x = the value of OUT at the cycle when IN last changed
Δ t = the elapsed time since the cycle when IN last changed, in seconds
When the FOLLOW parameter is set True (1), the filter algorithm is disabled and the block output (OUT) equals the input signal (IN).