Siemens Simatic S7-1500

Basics of program execution
10.3 Events and OBs
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF
323
10.3 Events and OBs
Start events
The table below gives an overview of the possible event sources for start events and their
OBs:
Table 10- 3 Start events
Event sources Possible priorities (default
priority)
Possible OB
numbers
Default system
response
1)
Number of OBs
Startup
1
100, ≥ 123
Ignore
0 to 100
Cyclic program
1
1, ≥ 123
Ignore
0 to 100
Time-of-day interrupt
2 to 24 (2)
10 to 17, ≥ 123
Not applicable
0 to 20
Time-delay interrupt
2 to 24 (3)
20 to 23, ≥ 123
Not applicable
0 to 20
Cyclic interrupt
2 to 24 (8 to 17, frequency
dependent)
30 to 38, ≥ 123
Not applicable
0 to 20
Hardware interrupt
2 to 26 (16)
40 to 47, ≥ 123
Ignore
0 to 50
Status interrupt
2 to 24 (4)
55
Ignore
0 or 1
Update alarm
2 to 24 (4)
56
Ignore
0 or 1
Manufacturer-specific or
profile-specific interrupt
2 to 24 (4)
57
Ignore
0 or 1
I/O redundancy error
2 to 26 (6)
70
Ignore
0 or 1
CPU redundancy error
2 to 26 (26)
72
Ignore
0 or 1
Time error
22 80
Ignore
0 or 1
Maximum cycle time exceed-
ed
Depends on sys-
tem state
2)
Diagnostics interrupt
2 to 26 (5)
82
Ignore
0 or 1
Removal/insertion of modules
2 to 26 (6)
83
Ignore
0 or 1
Rack error
2 to 26 (6)
86
Ignore
0 or 1
Programming error (only for
global error handling)
2 to 26 (7)
121
STOP
0 or 1
I/O access error (only for
global error handling)
2 to 26 (7)
122
Ignore
0 or 1
1)
If you have not configured the OB.
2)
See section "Response of S7-1500R/H redundant system when cycle time is exceeded"