Siemens SIMATIC S7-400H System Manual page 102

Link-up and update
9.3 Link-up and update
9. Transfer of outputs and of all data block contents modified again. Transfer of timers,
10. Lift all restrictions. Delayed interrupts and communication functions are executed. All OBs
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 state) 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 or expanded
memory configuration (Page 103).
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 messages
● 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.
102
counters, memory markers and inputs. Transfer of the diagnostics 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.
are executed again.
A constant cycle time compared with previous calls can no longer be guaranteed for
delayed cyclic interrupt OBs.
Note
Process and diagnostics interrupts are stored by the I/O. 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.
reference manual). For information on other aspects resulting from modifying the
System Software for S7-300/400, System and Standard
System Manual, 09/2007, A5E00267695-03
S7-400H