Performance
Section 3-2
26
Maximum I/O response time
The figure below shows the maximum I/O response time in asynchronous
mode. The figure shows the timing at the PLC, the timing at the Master Unit,
the timing at the slave input and the timing at the slave output.
t
IN
: The Input Slave’s ON (OFF) delay
t
OUT
: The Output Slave’s ON (OFF) delay
t
BC
: The Fieldbus cycle time
t
PC
: The Poll cycle time of the respective master
t
RF
: The I/O refresh time
t
PE
: The Program Execution time
The maximum response time can occur under the following conditions.
1.
The slave in question is polled by the respective master at the beginning
of the poll cycle.
2.
The Input data is available just after the master polled the respective
slave.
3.
The Master Unit finished processing just after the I/O refresh. The Input
data is not transferred to the PLC until the next PLC cycle.
4.
A fieldbus cycle just started before the end of the I/O refresh, the output
data is not transferred until the next fieldbus cycle.
The I/O response time in the case above is:
t
RESPONSE
= t
IN
+ 2 x t
BC
+ t
PC
+ 2 x t
RF
+ 2 x t
PE
+ t
OUT
Note:
With t
PC
is meant the time the master of the respective slave needs
to poll all slaves that have been assigned to this master.
Содержание C200HW-PRM21
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