Systemsoftware
2-18
System- and communication configuring D7-SYS - SIMADYN D
Edition 03.2001
2.1.6.2 Data transfer within the same task of a CPU
Each function block output in the system is assigned a memory location.
The function block saves its computed value in this memory location after
being processed. All inputs, which are connected with the outputs in the
same task, retrieve their values from the memory locations assigned to
the connected output. In order to prevent deadtimes, the blocks of a task
should if possible be computed corresponding to the "signal flow“, i. e.
that block whose outputs are used as inputs for the following block is first
computed etc.
2.1.6.3 Data transfer between various CPU tasks
Data transfer between various tasks of a CPU is realized via a buffer
system so that the data consistency can be guaranteed (refer to the
Chapter "Data consistency"). However, for data transfer from a faster to a
slower task, it should be observed that value changes are not sensed in
the slow task or are only sensed with a delay. If this cannot be tolerated,
then the software must be appropriately adapted, e. g. using pulse-
extending function blocks.
Start/end of
a cycle
Signal edge
Task T2
Task T3 Data transfer via
an alternating buffer
system
t
t
Fig. 2-4
Signal not sensed in task 3
