Rockwell Automation 8520-ARM2 9/Series CNC AMP Reference Manual Documentation Set - Manual (Page 661)

Miscellaneous Parameters
Chapter 37
37-21
Analyzing Your System Timing
Figure 37.1 and Figure 37.2 show the sequence in which the control scans
system tasks and updates information. The system should be run under
worst-case conditions with this parameter set to a value well above the
expected final setting. A worst-case scenario can be created by operating
the control under these conditions:
Condition Affects the duration of these tasks in
the system foreground
your maximum number of configured axes Servo Read, Servo Write, Axis Control
your maximum number of PAL foreground elements PAL Foreground
your maximum number of axes in motion Interpolation
circular or helical type of interpolation (G02,G03)
cutter compensation
probing
homing
Condition Affects the duration of these tasks in
the system background
your maximum number of characters in the block Part Program Decode
your maximum number of PAL background elements PAL Background
Figure 37.1
Scan Sequence of the 9/230 and 9/260 CPU
Servo Read PAL Foreground Interpolation Servo Write
Part Program Decode
PAL Background
Display Update
Low Level Diagnostics
Servo Read Axis Control
System Scan Time (8-30 ms; AMP selectable)
System Foreground System Background
Critical Foreground must be greater than 2ms