How To Plan The Macrocycle - Siemens Simatic PCS 7 Commissioning Manual

Engineering
4.3 Parameter assignment
4.3.4

How to plan the macrocycle

A macro cycle lasts for a number of bus clock cycles. The duration of the cyclic communication
depends on the configured hardware. You can define the time for a macro cycle and the
percentage of acyclic communication. The FF specifications recommend that at least 50% of
the bus time is kept free for acyclic communication.
For additional information, refer to the section "Nodes in the FOUNDATION Fieldbus
(Page 17)".
"Macrocycle" tab
Whether the configuration is consistent is determined on the basis of the output values and
the required interconnections. The result is displayed graphically.
"Calculate Schedule" button"
● Click this button to calculate the time for cyclic communication.
"Optimize macro cycle" button
● Click this button to set the macro cycle as follows:
Graphical display
Before downloading, click the "Calculate schedule" button. With the help of the display you
can check whether the configuration is consistent. The result is displayed graphically.
Display from left to right:
● Left area
● Left thin dividing line (50% of the bus load)
● Thick dividing line
● Right thin dividing line (70% of the bus load)
● Right area
Meaning of the colored areas
● Yellow
● Dark green
42
Depending on the cyclical component (depending on the configured hardware), a minimum
macro cycle is set with a specified acyclical percentage.
The colored area on the left side indicates the percentage of acyclic communication.
The lower limit of the percentage of acyclic communication of the bus load recommended
in the FF specifications.
The limiting value set in the entry field "Percentage of acyclic communication".
The upper limit of the percentage of acyclic communication of the bus load recommended
in the FF specifications.
The colored area on the right side indicates the percentage of cyclic communication.
Percentage of acyclic communication
Percentage of cyclic communication Configuration is free from errors.
Commissioning Manual, 03/2013, A5E03880935-02
FOUNDATION Fieldbus