Technical data

Table Of Contents
Generating Block-Related Messages
System Software for S7-300/400 System and Standard Functions - Volume 2/2
24-20
A5E00739858-01
24.8 Disabling Block-Related, Symbol-Related and Group
Status Messages with SFC 10 "DIS_MSG"
Description
With SFC 10 "DIS_MSG" (disable message) you can disable block-related
messages generated with SFBs, symbol-related messages (SCAN) and group
status messages. You select messages to be disabled using the input parameters
MODE and MESGN. Calling SFC 10 "DIS_MSG" and successfully disabling a
message is only possible when the disabling of a message is not already active
with SFC 10.
Messages that are ready to be sent when SFC 10 is called but that are still in an
internal buffer can no longer be disabled and are sent. A disabled message is
indicated at the ERROR and STATUS outputs of the "NOTIFY", "NOTIFY_8P",
"ALARM", "ALARM_8P" and "ALARM_8" SFBs.
You start the disabling of a message by assigning the value 1 to the REQ input
parameter when SFC 10 is called.
How SFC 10 Functions
Disabling is executed asynchronously, in other words it can be active throughout
several SFC 10 calls (see also Meaning of the Parameters REQ, RET_VAL and
BUSY with Asynchronous SFCs)
When it is first called (REQ =1), SFC 10 checks the input parameters and
attempts to occupy the required system resources. If successful, the value
W#16#7001 is entered in RET_VAL, BUSY is set and disabling the message is
started.
If unsuccessful, the error information is entered in RET_VAL and the job is
terminated. BUSY must not be evaluated in this case.
If there are further calls in the meantime, the value W#16#7002 is entered in
RET_VAL (job still being executed by the CPU) and BUSY is set. Further calls
do not affect the current job.
The last time the SFB is called, the value W#16#0000 is entered in RET_VAL if
no error occurred. BUSY then has the value 0. If an error occurred, the error
information is entered in RET_VAL and BUSY must not be evaluated.
Parameter Declaration Data Type Memory Area Description
REQ INPUT BOOL I, Q, M, D, L REQ = 1: trigger disable
MODE INPUT BYTE I, Q, M, D, L,
constant
Parameter for selecting the messages to
be disabled, see following table
MESGN INPUT DWORD I, Q, M, D, L,
constant
Message number only relevant when
MODE is set to 5, 6, 7. This allows a
single message to be disabled.
RET_VAL OUTPUT INT I, Q, M, D, L Error information, see table "Error
Information"
BUSY OUTPUT BOOL I, Q, M, D, L BUSY = 1: disable has not yet been
canceled.