Omron C40K 用户手册

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.

Input 

signal

Output 

signal

Cycle

Cycle time

I/O refresh

I/O response time

CPU reads 

input signal

CPU writes 

output signal

Output ON delay

Input ON delay

Overseeing

Cycle 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

1.5 ms

Cycle time

20 ms

Input refresh time

0.23 ms

Overseeing time

3.0 ms

Output ON-delay

15 ms

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