8-1
Section
CPM1/CPM1A Cycle Time and I/O Response Time
514
The average processing time for a single instruction in the user’s program is as-
sumed to be 2.86
µ
s. The cycle times are as shown in the following table.
Process
Calculation method
Time with
Programming Device
Time without
Programming Device
1. Overseeing
Fixed
0.6 ms
0.6 ms
2. Program execution
2.86
×
500 (
µ
s)
1.43 ms
1.43 ms
3. Cycle time calculation
Negligible
0 ms
0 ms
4. I/O refresh
0.01
×
1 + 0.005
×
1 (
µ
s)
0.06 ms
0.06 ms
5. Peripheral port servicing
Minimum time
0.26 ms
0 ms
Cycle time
(1) + (2) + (3) + (4) + (5)
2.35 ms
2.09 ms
Note
1. The cycle time can be read from the PC via a Programming Device.
2. The maximum and current cycle time are stored in AR 14 and AR 15.
3. The cycle time can vary with actual operating conditions and will not neces-
sarily agree precisely with the calculated value.
8-1-3 I/O Response Time
The I/O response time is the time it takes after an input signal has been received
(i.e., after an input bit has turned ON) for the PC to check and process the in-
formation and to output a control signal (i.e., to output the result of the proces-
sing to an output bit). The I/O response time varies according to the timing and
processing conditions.
The minimum and maximum I/O response times are shown here, using the fol-
lowing program as an example.
Input
Output
The following conditions are taken as examples for calculating the I/O response
times.
Input ON delay:
8 ms (input time constant: default setting)
Overseeing time:
1 ms (includes I/O refresh for CPM1A)
Instruction execution time:
14 ms
Output ON delay:
10 ms
Peripheral port:
Not used.
Minimum I/O Response Time
The CPM1/CPM1A responds most quickly when it receives an input signal just
prior to I/O refreshing, as shown in the illustration below.
Input ON delay (8 ms)
I/O refreshing
Input
point
Input
bit
Output
point
I/O refreshing
Program execution and other processes
(15 ms)
Min. I/O response time = 8+15+10 = 33 ms
Output ON delay (10 ms)