Omron CVM1-CLK21, Operation Manual

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Data Link I/O Response Time Section 8-3
The equation for maximum data link I/O response time is as follows:
Note If the total number of data link words is greater than the maximum number of
words that can be exchanged per data exchange, the maximum data link I/O
response time will be cycle time of PC at node #7
×
4.
In case of the CQM1H, however, the cycle time will be incremented by the
value obtained from dividing the total number of data link words by the maxi-
mum number of words (1,200 words) per time.
For example, if the total number of data link words is 5,000, the result will be
as shown below.
5,000/1,200 = 2.5 (approx. 3)
Cycle time of PC at node #7
×
(3+3)
Noise may increase I/O delays.
Case 2
The following diagram illustrates the data flow that will produce the maximum
data link I/O response time when the cycle time of the PC at node #1
≥
the
communications cycle time and the cycle time of the PC at node #7 < the
communications cycle time.
There are three points shown in the diagram above where processing is
delayed, increasing the data link I/O response time.
Input ON delay 1.5 ms
Cycle time of PC at node #1
×
2 15 ms
×
2
Communications cycle time
×
3 9.9 ms
×
3
PC cycle time at node #7
×
3 (see note) 20 ms
×
3 (see note)
Output ON delay 15 ms
Total (data link I/O response time) 136.2 ms
Input device
Program
Program
Input
Input ON delay
1 cycle
Output
Output device
Output ON
delay
1 cycle
Communications
cycle time
Data link transmission
Controller Link Unit
transmission processing
PC at node #7
(1)
I/O refresh
Data exchange
Controller Link Unit
transmission processing
PC at node #1
Data link I/O response time
X
X
(2)
(3)
X