Diagnostic Error Interrupt Ob - Siemens S7-1200 System Manual

All time error events trigger the execution of the time error interrupt OB if it exists. If the time
error interrupt OB does not exist, then the device configuration of the CPU determines the
CPU reaction to the time error:
● The default configuration for time errors, such as starting a second cyclic interrupt before
● The default configuration for exceeding the maximum time is for the CPU to change to
The user program can extend the program cycle execution time up to ten times the
configured maximum cycle time by executing the RE_TRIGR instruction (Page 262) to
restart the cycle time monitor. However, if two "maximum cycle time exceeded" conditions
occur within the same program cycle without resetting the cycle timer, then the CPU
transitions to STOP, regardless of whether the time error interrupt OB exists. See the section
on "Monitoring the cycle time in the S7-1200 System Manual" (Page 97).
Time error interrupt OB includes start information that helps you determine which event and
OB generated the time error. You can program instructions inside the OB to examine these
start values and to take appropriate action.
Table 4- 5
Input
fault_id
csg_OBnr
csg_prio
To include a time error interrupt OB in your project, you must add a time error interrupt by
double-clicking "Add new block" under "Program blocks" in the tree, then choose
"Organization block", and then "Time error interrupt".
The priority for a new V4.0 CPU is 22. If you exchange a V3.0 CPU for a V4.0 CPU
(Page 995), the priority is 26, the priority that was in effect for V3.0. In either case, the
priority field is editable and you can set the priority to any value in the range 22 to 26.
4.1.3.7

Diagnostic error interrupt OB

The diagnostic error interrupt OB executes when the CPU detects a diagnostic error, or if a
diagnostics-capable module recognizes an error and you have enabled the diagnostic error
interrupt for the module. The diagnostic error interrupt OB interrupts the normal cyclic
program execution. You can include an STP instruction in the diagnostic error interrupt OB to
put the CPU in STOP mode if you desire your CPU to enter STOP mode upon receiving this
type of error.
If you do not include a diagnostic error interrupt OB in your program, the CPU ignores the
error and stays in RUN mode.
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
the CPU has finished the execution of the first, is for the CPU to stay in RUN.
STOP.
Start information for the time error OB (OB 80)
Data type
BYTE
OB_ANY
UINT
Description
16#01 - maximum cycle time exceeded
16#02 - requested OB cannot be started
16#07 and 16#09 - queue overflow occurred
Number of the OB which was being executed when the error
occurred
Priority of the OB causing the error
PLC concepts
4.1 Execution of the user program
89