Systemsoftware
System- and communication configuring D7-SYS - SIMADYN D
2-31
Edition 03.2001
It is practical to transmit the interrupt task at the start, if several alarm
interrupts must start in synchronism on several CPU modules without any
delay. However, the interrupt task on the receiver CPU module may end
before the interrupt task on the transmitting CPU module as the
transmitting task was inhibited by a higher-priority interrupt.
If transmitted at the end, it is ensured that the task on the receive side is
not started before the transmit task has been completed. This second
possibility can be used when data is being transferred from a transmit- to
a receive task.
2.1.8.9 Example of a synchronization configuration
TG: Basic clock cycle
PA: Process interrupt
Fig. 2-10
Synchronization configuration
In Fig. 2-10
Synchronization configuration, CPU 1 transmits its basic
clock cycle onto the L bus. Further, the C bus interrupt is used as
interrupt event by an interrupt-controlled task of the CPU 1.
CPU 2 retrieves its basic clock cycle from the basic clock line of the L bus
and switches the interrupt from counter C1 (configuration with function
block PAC) to the L bus interrupt line.
CPU 3 retrieves its basic clock cycle from the L bus interrupt line and
switches the interrupt, received via the binary input (configuration with
function block PAI) to the C bus interrupt line.
2.1.9 Significance of the processor utilization
2.1.9.1 Determining the approximate processor utilization
When compiling, the CFC determines a value for the CPU computation
time utilization. A list is accessed, in which the computation time of a
block is entered for each function block type. When developing the
blocks, these computation times are determined for the "worst case", and
are specified in the User documentation, function block library (Edition in
Autumn 1997).
For several function blocks, especially for blocks, which access
hardware, the worst case situation will generally result in higher time and
therefore a typical computation type is used (e. g. for medium bus load
levels). Based on these nominal values, for several function block types,
the actual computation time can fluctuate significantly.
The computation time, entered in the block catalog, specifies the typical
block computation time on a PM5 in
µ
s. However, this value especially for
communication blocks, can deviate from the actually required time,
depending on the quantity of data to be transferred.
Transmitting at the
start of interrupt
task processing
Transmitting at the
end of of interrupt
task processing
Description
