Calculating Cycle Time - Omron SYSMAC CVM1 Series Operation Manual

Calculating Cycle Time

Calculations
424
ing into account such things as the number of I/O points, the programming
instructions used, and whether or not Programming Devices are being used.
This section shows a basic example of cycle time calculation. Operating
times are given in the tables in 6-2 Cycle Time.
Here, we'll compute the cycle time for a CVM1D controlling only I/O Units,
five on the CPU Rack and ten on an Expansion I/O Rack. The PC configura-
tion for this is shown below. It is assumed that the program contains 20,000
instructions requiring an average of 0.3 µs each to execute.
Refer to the next section for instruction execution times. Using the cycle time
in calculating the I/O response time is described in the last part of Section 6.
16-point Input 16-point Output
Units Units
32-point Input 32-point Output
Units Units
The following table shows the time required for each process in the cycle.
Process
1 Overseeing time ---
(basic processes)
20,000 steps × 0.3 µs
2 Program execution
[(16 points × 2 + 32 points × 5) ÷ 16] × 7 µs
3 Output refreshing
[(16 points × 3 + 32 points × 5) ÷ 16] × 8 µs
4 Input refreshing
5 I/O bus check ---
[(16 points × 3 + 32 points × 5) ÷ 16] × 10 µs
6 Duplex refreshing
Approximate cycle time (processes 1 through 5)
CPU Rack
Expansion I/O Rack
Calculation
Section 6-3
Time (ms)
8.5
6.0
0.084
0.104
1.2
0.11
16.00