Controller Link Units Operation Manual

257
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 PLC 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 PLC at node #7
× (3+3)
The PLC cycle time when data link words exceed 12,000 using a CS/CJ-
series Controller Link Unit with unit version 1.2 or later is calculated as fol-
lows.
12,000 to 15,600 (approx.) words:
× 3
15,600 (approx.) to 20,000 words:
× 4
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 PLC at node #1
≥ the
communications cycle time and the cycle time of the PLC at node #7 < the
communications cycle time.
Input ON delay 1.5 ms
Cycle time of PLC at node #1 × 2 15 ms × 2
Communications cycle time × 3 9.9 ms × 3
PLC 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