Siemens SIMATIC CPU 410 System Manual page 349

9. Transfer of outputs and of all data block contents modified again. Transfer of timers,
counters, bit memories, and inputs. Transfer of the diagnostic buffer.
During this data synchronization, the system interrupts the clock pulse for cyclic
interrupts, time-delay interrupts and S7 timers. This results in the loss of any synchronism
between cyclic and time-of-day interrupts.
10.Cancel all restrictions. Delayed interrupts and communication functions are executed. All
OBs are executed again.
A constant bus cycle time compared with previous calls can no longer be guaranteed for
delayed cyclic interrupt OBs.
Note
Process interrupts and diagnostic interrupts are stored by the I/O devices. Such interrupt
requests issued by distributed I/O modules are executed when the block is re-enabled.
Any such requests by central I/O modules can only be executed provided the same
interrupt request did not occur repeatedly while the status was disabled.
If the PG/ES requested a master/standby changeover, the previous standby CPU assumes
master mode and the previous master CPU goes into STOP when the update is completed.
Both CPUs will otherwise go into RUN (redundant system mode) and execute the user
program in synchronism.
When there is a master/standby changeover, in the first cycle after the update OB 1 is
assigned a separate identifier (see
Functions
configuration, refer to section Switch to CPU with modified configuration (Page 351).
Delayed message functions
The listed SFCs, SFBs and operating system services trigger the output of messages to all
logged-on partners. These functions are delayed after the start of the update:
● SFC 17 "ALARM_SQ", SFC 18 "ALARM_S", SFC 107 "ALARM_DQ", SFC 108
"ALARM_D"
● SFC 52 "WR_USMSG"
● SFB 31 "NOTIFY_8P", SFB 33 "ALARM", SFB 34 "ALARM_8", SFB 35 "ALARM_8P",
SFB 36 "NOTIFY", SFB 37 "AR_SEND"
● Process control alarms
● System diagnostics messages
From this time on, any requests to enable and disable messages by SFC 9 "EN_MSG" and
SFC 10 "DIS_MSG" are rejected with a negative return value.
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC
Reference Manual). For information on other aspects resulting from modifying the
18.13 Link-up and update sequence
System Software for S7-300/400, System and Standard
Supplementary information
349