Siemens SIMATIC S7-1200 - Page 425

Extended instructions
9.5 Interrupts
S7-1200 Programmable controller
System Manual, V4.2, 09/2016, A5E02486680-AK
425
If lower and higher priority OBs are called in the same time interval, the lower priority OB is
only called after the higher priority OB has finished processing. The execution start time for
the low priority OB can shift depending on the processing time of higher priority OBs.
If you want to start the execution of a lower priority OB on a fixed time cycle, then phase shift
time should be greater then the processing time of higher priority OBs.
Table 9- 102 Condition codes
RET_VAL (W#16#....)
Description
0000
No error
8090
OB does not exist or is of wrong type
8091
Invalid cycle time
8092
Invalid phase shift time
80B2
OB has no attached event