Technical data

Table Of Contents
Organization Blocks
System Software for S7-300/400 System and Standard Functions - Volume 1/2
A5E00709327-01
1-3
OB Start Event Default Priority
Class
Explanation
OB 61
OB 62
OB 63
OB 64
Synchronous Cycle Interrupt 1
Synchronous Cycle Interrupt 2
Synchronous Cycle Interrupt 3
Synchronous Cycle Interrupt 4
25
25
25
25
Synchronous Cycle
Interrupt
OB 65 Technology synchronization interrupt 25 Technology
synchronization
interrupt
OB70
OB72
OB 73
I/O redundancy error (only in H CPUs)
CPU redundancy error (only in H CPUs)
Communication redundancy error OB (only in
H CPUs)
25
28
25
Redundancy error
interrupts
OB80 Time error 26, 28
1)
Asynchronous error
interrupts
OB81
Power supply fault
26, 28
1)
with S7-300,
25, 28
1)
with S7-400
and CPU 318
OB82 Diagnostic interrupt 26, 28
1)
with S7-300,
25, 28
1)
with S7-400
and CPU 318
OB83
Insert/remove module interrupt
26, 28
1)
with S7-300,
25, 28
1)
with S7-400
and CPU 318
OB84
CPU hardware fault
26, 28
1)
with S7-300,
25, 28
1)
with S7-400
and CPU 318
OB85
Program error
26, 28
1)
with S7-300,
25, 28
1)
with S7-400
and CPU 318
OB86
Failure of an expansion rack, DP master
system or station for distributed I/Os
26, 28
1)
with S7-300,
25, 28
1)
with S7-400
and CPU 318
OB87
Communication error
26, 28
1)
with S7-300,
25, 28
1)
with S7-400
and CPU 318
OB 88 Processing interrupt 28
OB90 Warm or cold restart or delete a block being
executed in OB90 or load an OB90 on the
CPU or terminate OB90
29
2)
Background cycle
OB100
OB101
OB102
Warm restart
Hot restart
Cold restart
27
1)
27
1)
27
1)
Startup
OB121
OB122
Programming error
I/O access error
Priority of the OB
causing the error
Priority of the OB
causing the error
Synchronous error
interrupts
1)
Priority classes 27 and 28 are valid in the priority class model of the startup.
2)
Priority class 29 corresponds to priority 0.29. This means that the background cycle has lower
priority than the free cycle.