A-3.2 What The Sweep Impact Tables Contain - GE PACSystems RX7i Reference Manual

Appendix A. Performance Data
A-3.2 What the Sweep Impact Tables Contain
In some tables, functions are shown as asynchronously impacting the sweep. This means that there is
not a set phase of the sweep in which the function takes place. For instance, the scanning of all I/O
modules takes place during either the input or output scan phase of the CPU's sweep. However, I/O
interrupts are totally asynchronous to the sweep and will interrupt any function currently in progress.
The communication functions (except for the high priority programmer requests) are all processed within
one of the two windows in the sweep (the Controller Communications Window and the Backplane
Communications Window). Sweep impact times for the various service requests are all minimum sweep
impact times for the defined functions, where the window times have been adjusted so that no time
slicing (limiting) of the window occurs in each sweep. This means that, as much as possible, each function
is completed in one occurrence of the window (between consecutive logic scans). The sweep impact of
these functions can be spread out over multiple sweeps (limited) by adjusting the window times to a
value lower than the documented sweep impact time. For the programmer, the default time is 10 ms;
therefore, some of the functions listed in that section will naturally time slice over successive sweeps.
278 PACSystems* RX7i, RX3i and RSTi-EP CPU Reference Manual GFK-2222AD