Technical data

Table Of Contents
SFCs for Handling Interrupts and Asynchronous Errors
System Software for S7-300/400 System and Standard Functions - Volume 1/2
A5E00709327-01
12-3
12.2 Disabling the Processing of New Interrupts and
Asynchronous Errors with SFC 39 "DIS_IRT"
Description
With SFC 39 "DIS_IRT" (disable interrupt), you disable the processing of new
interrupts and asynchronous errors. This means that if an interrupt occurs, the
operating system of the CPU reacts as follows:
It neither calls an interrupt OB or asynchronous error OB,
Nor triggers the normal reaction if an interrupt OB or asynchronous error OB is
not programmed.
If you disable interrupts and asynchronous errors, this remains in effect for all
priority classes. The effects of "DIS_IRT" can only be canceled again by calling
SFC 40 "EN_IRT" or by a warm or a cold restart.
Whether the operating system writes interrupts and asynchronous errors to the
diagnostic buffer when they occur depends on the input parameter setting you
select for MODE.
Note
Remember that when you program the use of SFC 39 "DIS_IRT," all interrupts that
occur are lost!
Parameter Declaration Data Type Memory Area Description
MODE INPUT BYTE I, Q, M, D, L,
constant
Specifies which interrupts and asynchronous
errors are disabled.
OB_NR INPUT INT I, Q, M, D, L,
constant
OB number
RET_VAL OUTPUT INT I, Q, M, D, L If an error occurs while the function is active,
the return value contains an error code.