Omron SYSMAC CS1W-CLK13 Operation Manual page 252

Data Link I/O Response Time
CVM1 and CV-series PLCs Under Asynchronous Operation
Maximum Data Link I/O Response Time
1,2,3...
Input
Input device
Input ON response time
Program
Communications
cycle time
PLC at node #7
There are five points shown in the diagram above where processing is
delayed, increasing the data link I/O response time.
1. The input arrives in the PLC just after I/O refreshing, causing a delay of up
to one cycle before the input is read into the PLC.
2. Data exchange occurs just after the PLC at node #1 passes the token that
makes it the polling node, causing a delay of up to one communications cy-
cle time before the data is transferred in data link processing.
3. At node #1, 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 one peripheral servicing interval.
Up to 3,700 words can be transferred in a single data exchange, so a delay
of another peripheral servicing interval will occur if more than 3,700 words
are being transferred.
5. The data is received after the PLC at node #7 has executed the instruction,
causing a delay of up to one cycle time.
Assume that the peripheral servicing interval of the PLCs at nodes #1 and #7
is 10 ms. The equation for the maximum data link I/O response time is as fol-
lows:
Input ON delay
Cycle time of PLC at node #1 × 2
Peripheral servicing interval of PLC at
node #1
Communications cycle time × 2
Peripheral servicing interval of PLC at
node #7 × 2
PLC cycle time at node #7 × 2
Output ON delay
Total (data link I/O response time)
1 cycle
PLC at node #1
Peripheral servicing interval
Data link transmission
Peripheral servicing interval
Program
Output device
Output ON response time
Data link I/O response time
1.5 ms
25 ms × 2
10 ms
22 ms × 2
10 ms × 2
10 ms × 2
15 ms
160.5 ms
Section 9-3
I/O refresh
1 cycle
Output
229