Technical data

Diagnostics
23.9 Program Measures for Handling Errors
Programming with STEP 7
512 Manual, 05/2010, A5E02789666-01
23.9.6 Time Error (OB80)
Description
The operating system of the CPU calls OB80 when a time error occurs. Time errors include the
following, for example:
• Maximum cycle time exceeded
• Time-of-day interrupts skipped by moving the time forward
• Delay too great when processing a priority class
Programming OB80
You must create OB80 as an object in your S7 program using STEP 7. Write the program to be
executed in OB80 in the generated block and download it to the CPU as part of your user program.
You can use OB80, for example, for the following purposes:
• To evaluate the start information of OB80 and to determine which time-of-day interrupts were
skipped.
• By including SFC29 CANTINT, you can deactivate the skipped time-of-day interrupt so that it is
not executed and only time-of-day interrupts relative to the new time will be executed.
If you do not deactivate skipped time-of-day interrupts in OB80, the first skipped time-of-day
interrupt is executed, all others are ignored.
If you do not program OB80, the CPU changes to STOP mode when a time error is detected.
You can find detailed information on OBs, SFBs, and SFCs in the corresponding Help on Blocks.