Technical data

Table Of Contents
Glossary
System Software for S7-300/400 System and Standard Functions- Volume 2/2
A5E00739858-01
Glossary-5
Diagnostic Entry
A diagnostic event is described in the diagnostic buffer using a diagnostic entry.
Diagnostic Interrupt
Diagnostic modules report recognized system errors using diagnostic interrupts to
the CPU.
Diagnostic Message
The diagnostic message consists of a processed diagnostic event and is sent from
the CPU to the display unit.
Diagnostics
Diagnostic functions incorporate all the system diagnostics and include the
recognition, interpretation and reporting of errors within the PLC.
Display Device
A device used to display the results of a process.
Error, Asynchronous
Asynchronous errors are run time errors which are not assigned to any particular
place in the user program (for example, power supply error, scan time overrun).
When these errors occur, the operating system calls the corresponding
organization blocks in which the user can program a reaction.
Error Handling with OBs
If the system program recognizes a particular error (for example, access error in
S7), it will call the designated organization block in which the CPU’s response to
the error can be set by the user program.
Error OB
Error OBs are organization blocks which the user can use to program the reaction
to an error. However, a programmed reaction to an error is only possible if the error
does not cause the PLC to stop. There is an error OB for each type of error. (For
example, error OB for addressing error, error OB for access error in S7.)
Error Reaction
Reaction to a run-time error. The operating system can react in the following ways:
by changing the PLC to the STOP status, by calling an organization block in which
the user can program a reaction, or by displaying the error.