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Data Link I/O Response Time Section 8-3
3. At node #7, data from the previous data exchange is still being transferred,
causing a delay of up to one cycle before the input is read into the PLC.
4. The data transferred in data link processing arrives at the PLC at node #7
after data exchange, so the data will not be read into the PLC until the next
data exchange, causing a delay of up to 1 to 2 cycle.
The maximum number of words that can be exchanged in a single data ex-
change is approx. 7,800 words for CS/CJ-series PLCs, approx. 3,700
words for CVM1 and CV-series PLCs, approx. 4,000 for C200HX/HG/HE
PLCs, and approx. 1,200 words for CQM1H-series PLCs.
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.
Input ON delay 1.5 ms
Cycle time of PLC at node #1 × 28 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) 122.2 ms