Inserting Cfc Charts - Siemens SIMATIC S7 F Manual

Programming
For Fault-Tolerant Systems
In fail-safe and fault-tolerant S7 FH Systems, one or more separate cyclic
interrupts with a high priority should be reserved for the Safety Program. This is
necessary to prevent time monitoring being initiated in the case of a
master/standby switchover. To do this, you must configure the OB3x cyclic
interrupts provided for the Safety Program on the "Cyclic Interrupts" tab in the CPU
properties with a priority > 15. No standard blocks should then be placed in these
OBs.
5.2.4

Inserting CFC Charts

Rules for the CFC Charts of the Safety Program
Please note that separate charts must be created for the fail-safe section of the
user program.
Procedure
You can create individual CFC charts in the chart folder in the usual way:
•
By choosing the Insert > S7 Software > CFC menu command in SIMATIC
Manager
•
By choosing the Chart > New menu command in the CFC editor
Chart in Chart
In order to structure a program according, for example, to process-related aspects,
you can use a CFC chart within a CFC chart (Chart in Chart). This enables you to
use solutions already in existence as often as you want. You can find out how to
create Chart in Chart charts, assign them I/Os and insert them in other CFC charts
in the CFC online help system.
Note
If you nest a chart in another chart, you must make sure that the blocks of the
lower-level chart are in the same run-time group as those of the higher-level chart
(of the basic chart). If necessary, move them. Otherwise, you will receive an error
message when the Safety Program is compiled.
Chart outputs of a lower-level chart that are not interconnected internally cannot be
interconnected further in the higher-level chart.
5-8
Fail-Safe Systems
A5E00085588-03