Omron C200HX Operation Manual page 387

Calculating Cycle Time
6-2-1 PC with I/O Units Only
Calculations
(16 pts × 2) + (8 pts × 4)
8 pts
6-2-2 PC with Host Link and Remote I/O Master Units
Here, we'll compute the cycle time for a simple PC. The CPU Unit controls only
I/O Units, eight on the CPU Rack and five on a 5-slot Expansion I/O Rack. The
PC configuration for this would be as shown below. It is assumed that the pro-
gram contains 5,000 instructions requiring an average of 0.156 μs each to
execute.
8-point Input Units
16-point Input Units
8-point Output Unit
The equation for the cycle time from above is as follows:
Cycle time = Overseeing time + Program execution time + I/O refresh time +
Peripheral device servicing time
Process Calculation
Overseeing Fixed
0.156 μs/instruction
Program execution
× 5,000 instructions
I/O refresh See below.
Peripheral device Minimum time
servicing
Cycle time Total of above
The I/O refresh time would be as follows for two16-point Input Units, four 8-point
Input Units, two 12-point Output Units (12-point Units are treated as 16-point
Units), and five 8-point Output Units controlled by the PC:
(16 pts × 2) + (8 pts × 5)
× 20 μs +
Here, the cycle time is computed for a PC with a Host Link Unit and Remote I/O
Master Unit installed. The PC configuration for this could be as shown below.
The CPU Unit controls three 8-point Input Units, three 8-point Output Units, a
Host Link Unit, and a Remote I/O Master Unit connected to a Remote I/O Slave
Rack containing four 16-point Input Units and four 12-point Output Units.
8-point Output Units
Expansion I/O Rack
12-point Output Units
With Peripheral
Device
0.7 ms
0.78 ms
0.34 ms
0.26 ms
2.08 ms
× 20 μs = 0.34 ms
8 pts
Section 6-2
CPU Rack
Without
Peripheral Device
0.7 ms
0.78 ms
0.34 ms
0.0 ms
1.82 ms
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