Technical data

Table Of Contents
SFCs for Handling Synchronous Errors
System Software for S7-300/400 System and Standard Functions - Volume 1/2
11-2
A5E00709327-01
Handling Errors in General
If programming and access errors occur in a user program, you can react to them
in different ways:
You can program an error OB that is called by the operating system when the
corresponding error occurs.
You can disable the error OB call individually for each priority class. In this
case, the CPU does not change to STOP when an error of this type occurs in
the particular priority class. The CPU enters the error in an error register. From
this entry, however, you cannot recognize when or how often the error occurred.
Error masked?
Synchronous error
NO
Y
ES
The reaction to an
error is
p
ro
g
rammed
in the OB.
An error is entered
in the error register.
Error OB call (the
CPU changes to
STOP if the error
OB is not
programmed).
Error OB call
(the CPU does
not chan
g
e to STOP
if an error occurs
)
.
disabled
Filters
Synchronous errors are assigned to a particular bit pattern known as the error
filter (mask). This error filter is also in the input and output parameters of SFCs 36,
37 and 38.
The synchronous errors are divided into programming and access errors that you
can mask using two error filters. The error filters are illustrated in the following
Figures.