Siemens SIMATIC S7-1500 Function Manual page 81

Overflows
If the set application cycle is not adhered to, for example because the application cycle is too
short, overflows can occur.
The CPU will not tolerate overflow of MC-Servo [OB91]. An overflow will cause the CPU to
change to STOP mode.
The following figure shows the operational sequence if there is an overflow of MC-Servo
[OB91]:
The execution of an MC-Interpolator [OB92] may only be interrupted by an MC-Servo [OB91]
call. If more interruptions occur, the CPU switches to STOP mode.
The following figure shows the sequence when an MC-Interpolator [OB92] is interrupted over
two time slices:
S7-1500 Motion Control V13 Update 3
Function Manual, 07/2014, A5E03879256-AC
Basics
3.20 Operational sequence
81