492
Cycle Time
Section 7-3
The following conditions are taken as examples for calculating the I/O
response times.
Input ON delay:
8 ms
Overseeing time:
1 ms
Instruction execution time:
14 ms
Output ON delay:
10 ms
Position of output instruction:
Beginning of program
Communications ports:
Not used.
Note
The input ON delay for DC Input Units can be set in the PC Setup.
Minimum I/O Response
Time
The CQM1H responds most quickly when it receives an input signal just prior
to the input refresh phase of the cycle, as shown in the illustration below.
When cyclic output refreshing is used:
Minimum I/O response time = 8 + 15 + 10 = 33 ms
When direct output refreshing is used:
Minimum I/O response time = 8 + 1 + 10 = 19 ms
Note
Faster response times (100
µ
s standard)
can be achieved by using input inter-
rupts and direct output refreshing.
Maximum I/O Response
Time
The CQM1H takes longest to respond when it receives the input signal just
after the input refresh phase of the cycle, as shown in the illustration below. In
that case, a delay of approximately one cycle will occur.
When cyclic output refreshing is used:
Minimum I/O response time = 8 + 15
×
2 + 10 = 48 ms
When direct output refreshing is used:
Minimum I/O response time = 8 + 15 + 10 = 33 ms
Input ON delay
With direct output refresh
Instruction execution
Output ON
delay
Cycle time
With cyclic output refresh
I/O refresh
Overseeing, etc.
Output point
Input
point
Input
bit
CPU
processing
Instruction execution
Cycle time
I/O refresh
Overseeing, etc.
Input ON delay
Input
point
Input
bit
CPU
processing
Instruction execution
Instruction execution
Instruction execution
Output ON
delay
Output point
With direct output refresh
With cyclic output refresh
