Technical data

Table Of Contents
Generating Block-Related Messages
System Software for S7-300/400 System and Standard Functions - Volume 2/2
A5E00739858-01
24-3
Acknowledging Messages with SFBs 33 "ALARM", 34 "ALARM_8" and 35
"ALARM_8P"
A centralized acknowledgment concept is used. When you have acknowledged the
message at a display device, the acknowledgment information is first sent to the
CPU that generated the message. From here, the acknowledgment information is
distributed to all stations logged on for this purpose.
You acknowledge a signal and not an individual message. If, for example, several
rising edges of a signal were indicated and you acknowledge the event entering the
state, all previous events with the same message number count as having been
acknowledged.
Acknowledgment Display
SFB 36 "NOTIFY" and SFB 31 "NOTIFY_8P" do not have an acknowledgment
indication. You can check the output parameters ACK_UP and ACK_DN of SFB 33
"ALARM" and the output parameter ACK_STATE of SFBs 35 "ALARM_8P" and 34
"ALARM_8." These outputs are updated when the block is called, providing the
control parameter EN_R has the value 1.
Disabling and Enabling Messages via SFC or Displaying Devices (WinCC)
In some situations, it may be useful to suppress messages (e.g. when you
reconfigure your system). You can therefore disable and enable messages at the
display device or in your program. Disabling/enabling applies to all stations that
logged on for the particular message. A disabled message remains disabled until it
is enabled again.
You are informed of disabled messages with the ERROR and STATUS output
parameters (ERROR = 1, STATUS = 21).
Memory resources required by the SFBs for generating block-related messages
For their proper operation, SFBs that generate block-related messages require
intermediate memory space in the communications data buffer of the CPU,
depending on the length of associated value data. Refer to the table below for
information on the size of used memory.
Block type Required space (in bytes) in the working memory of the CPU
NOTIFY 200 + 2 * Length of the associated values specified at SD_1,...SD_10 at the first call
NOTIFY_8P 200 + 2 * Length of the associated values specified at SD_1,...SD_10 at the first call
ALARM 200 + 2 * Length of the associated values specified at SD_1,...SD_10 at the first call
ALARM_8 100
ALARM_8P 200 + 2 * Length of the associated values specified at SD_1,...SD_10 at the first call
AR_SEND 54