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CPM1/CPM1A Cycle Time and I/O Response Time Section 7-2
The average processing time for a single instruction in the user’s program is
assumed to be 2.86
µs. The cycle times are as shown in the following table.
Note 1. The cycle time can be read from the PC via a Peripheral 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 nec-
essarily agree precisely with the calculated value.
7-2-3 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 pro-
cess the information and to output a control signal (i.e., to output the result of
the processing 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
following program as an example.
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.
Process Calculation method Time with peripheral device Time without peripheral
device
1. Overseeing Fixed 0.6 ms 0.6 ms
2. Program execution 2.86 × 500 (µs) 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 (µs) 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
Input
Output
Input ON delay (8 ms)
I/O refreshing
Input
point
Input
bit
Output
point
I/O refreshingProgram execution and other processes
(15 ms)
Min. I/O response time = 8+15+10 = 33 ms
Output ON delay (10 ms)
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