Technical data

Table Of Contents
System Software for S7-300/400 System and Standard Functions - Volume 2/2
A5E00739858-01
29-1
29 SFCs for H CPUs
29.1 Controlling Operation in H Systems with SFC 90
"H_CTRL"
Description
With SFC 90 "H_CTRL," you can influence H systems as follows:
You can prevent the standby link-up in the master CPU. This is then disabled
until you cancel the setting with SFC 90 "H_CTRL" or the H system goes into
STOP mode.
Any request from the standby CPU to link-up with the master is stored.
You can disable updating on the master CPU. This is then disabled until you
cancel the setting with SFC 90 "H_CTRL" or the H system goes into STOP
mode.
Any request from the standby CPU to update is stored.
!
Caution
If you have disabled update but not connect, the hardware system still can
determine the connection status as before. Please note that when the master CPU
is connecting, it does not process any remove/insert interrupts, station
failure/returned interrupts or rack failure/returned interrupts.
You can remove a test component from the cyclical self-test, add it again or
start immediately. If you have disabled one or more test components of the
cyclical self test, the component or components remain disabled until you
cancel the setting with SFC 90 "H_CTRL" or the H system goes into STOP
mode.
Note:
If you use a CPU 414-4H or 417-4H in a redundant system, please observe the
following: If you disable the component for more than 24 hours, the CPU goes
into STOP mode. For redundant systems, the applicable regulation states that
certain tests must be completed within 24 hours.