Hi, The VI "IIR Cascade Filter with I.C." actually let's you pass to the filter the initial condition of the filter's circular buffer. This feature will help you pass any initial data for the buffer.
The use of the initial condition is reserved for cases where you are performing a filter and you want to specify an initial condition to avoid the settling time involved in a digital filter. In general if the order of the filter is not very high and the data buffer is long enough you don't need the initial condition; probably using the "IIR Cascade Filter" will do it. Hope this helps. Regards, Juan Carlos N.I.