Omron SYSMAC C20K Operation Manual page 157

I/O Response Time
Maximum I/O Response
Time
Overseeing
Cycle
Input
signal
Output
signal
Calculation Example
146
The PC takes longest to respond when it receives the input signal just after
the input refresh phase of the cycle. In this case the CPU does not recognize
the input signal until the end of the next cycle. The maximum response time
is thus one cycle longer than the minimum I/O response time, except that the
input refresh time would not need to be added in because the input comes
just after it rather than before it.
Cycle time
I/O refresh
CPU reads
input signal
Input ON delay
I/O response time
Maximum I/O response time = input ON delay + (cycle time x 2) + overseeing
time + output ON delay
The data in the following table would produce the minimum and maximum
cycle times shown calculated below.
Input ON-delay
Cycle time
Input refresh time
Overseeing time
Output ON-delay
Minimum I/O response time = 1.5 + 20 + 0.23 + 3.0 +15 = 39.73 ms
Maximum I/O response time = 1.5 + (20 x 2) + 3.0 +15 = 59.5 ms
Cycle time
CPU writes
output signal
Output ON delay
1.5 ms
20 ms
0.23 ms
3.0 ms
15 ms
Section 6-5