Siemens SIMATIC S7-1500 Function Manual page 79

Application cycle
You can set the application cycle in which the MC-Servo [OB91] is called in the properties of
the organization block in "General > Cycle Time":
● Synchronous to the bus
● Cyclic
The selected application cycle must be long enough to be able to process the technology
objects in one cycle. If the processing time of the technology objects is longer than the
application cycle, overflows (Page 80) will occur.
You can check the runtime of MC-Servo [OB91] and MC-Interpolator [OB92] with the
expanded instruction "RT_INFO".
Clock reduction (CPU V1.5 and higher)
You can reduce the application cycle of the MC-Servo [OB91] relative to the send clock of an
isochronous PROFINET IO system. You can set an integer multiple of the send clock as the
factor. Values up to 14 times the send clock (maximum 32 ms) are possible for the
application cycle.
If you call a isochronous interrupt OB and the MC-Servo [OB91] synchronously with the
same PROFINET IO system, set the same application cycle for both organization blocks.
Priority
You can configure the priority of the organization blocks as needed in their properties under
"General > Properties > Priority":
● MC Servo [OB91]
● MC Interpolator [OB92]
The priority of MC Servo [OB91] must be at least one higher than the priority of the
MC Interpolator [OB92].
S7-1500 Motion Control V13 Update 3
Function Manual, 07/2014, A5E03879256-AC
MC-Servo [OB91] is called synchronously with or at a reduced ratio to a bus system. You
set the send clock in the properties of the selected bus system. In the "Distributed I/O"
drop-down list, you can select the following bus systems:
– Isochronous PROFIBUS DP
– Isochronous PROFINET IO
You cannot call the MC-Servo [OB91] synchronously with a bus system that is connected
to the CPU via a communications processor/communications module (CP/CM).
The MC-Servo [OB91] is called cyclically with the specified application cycle.
Priority 17 to 31 (default value 25)
Priority 16 to 30 (default value 24)
Basics
3.20 Operational sequence
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