Description And Use Of The Signal Transfer Mechanisms; Data Consistency - Siemens SIMADYN D Manual

2.1.6 Description and use of the signal transfer mechanisms

2.1.6.1 Data consistency

System- and communication configuring D7-SYS - SIMADYN D
Edition 03.2001
The assignment of the function blocks to the cyclic tasks and the interrupt
tasks can be changed using the Edit > Sequence menu item.
When configuring has been completed, the generated software can be
checked with the Chart > Check consistency menu item, and then
compiled into the machine code with Chart > Compile.
The Target system > Load menu item then allows the memory module
to be programmed.
Signal transfer is data exchange between various blocks.
e. g. integrator
1ms ; 1. CPU
Fig. 2-3 Data transfer between two tasks
For interconnections between different cyclic tasks, SIMATIC
TDC/SIMADYN D ensures the consistency of all data which is
transferred. This means, that all data transferred from a task come from
the same computation cycle of this task. All values calculated during a
sampling cycle are "exported" at the end of the task. When starting a
task, the required values are "imported", whereby it is ensured that there
is no overlap (from a time perspective) between reading and writing the
values (buffer system). As deadtimes are unavoidable with this concept,
a signal should not be routed via several tasks and CPUs - if this can be
avoided.
A differentiation is made between the following signal transfer types :
• Data transfer within the same task of a CPU
• Data transfer between various tasks of a CPU
• Data transfer between cyclic tasks of several CPUs
• Data transfer between alarm tasks of several CPUs
Signal transfer
Systemsoftware
e. g. multiplier
4,2 ms ; 2. CPU
2-17