Window Modes - GE PACSystems RX7i Reference Manual

4.3

Window Modes

The previous section describes the phases of a typical CPU sweep. The Controller Communications,
Backplane Communications, and Background windows can be run in various modes, based on the CPU
sweep mode. (Refer to CPU Sweep Modes.) The following three window modes are available:
Run-to- In Run-to-Completion mode, all requests made when the window has started are
Completion serviced. When all pending requests in the given window have completed, the
CPU transitions to the next phase of the sweep. (This does not apply to the
Background window because it does not process requests.)
Constant In Constant Window mode, the total amount of time that the Controller
Communications window, Backplane Communications window, and Background
window run is fixed. If the time expires while in the middle of servicing a request,
these windows are closed, and communications will be resumed the next sweep.
If no requests are pending in this window, the CPU cycles through these windows
the specified amount of time polling for further requests. If any window is put in
constant window mode, all are in constant window mode.
Limited In Limited mode, the maximum time is fixed for the execution of the window. If
time expires while in the middle of servicing a request, the window is closed, and
communications will be resumed the next time that the given window is run. If no
requests are pending in this window, the CPU proceeds to the next phase of the
sweep.
GFK-2222AD April 2018
Chapter 4. CPU Operation
147