![background image](http://html1.mh-extra.com/html/omron/sysmac-c1000h/sysmac-c1000h_operation-manual_743079239.webp)
234
below. It is assumed that the program contains 20,000 instructions requiring
an average of 0.6
µ
s each to execute.
Computer
Next PC in
PC Link System
32-point Output Unit
16-point Output Unit
32-point Input Unit
16-point Input Unit
Optical Remote I/O Slave Unit
Slave Rack
Host Link Unit
PC Link Unit
Optical Remote I/O Master Unit
16-point
Input
Unit
16-point
Output
Unit
CPU I/O Rack
CPU Rack
The equation for the cycle time is as follows:
Cycle time = overseeing time
+ output refreshing and Unit servicing time
+ input refreshing time
The overseeing time is fixed at 3.0 ms plus 1.0 ms (for synchronization of
Duplex CPUs), or 4.0 ms. The input refresh time is 3 Units x 25
µ
s per
16-point Input Unit, or 0.08 ms
The output refreshing and Unit servicing time equals the I/O bus check time
plus the output refresh time plus the Remote I/O servicing time plus the pe-
ripheral device and Link Unit servicing time. The I/O bus check time is fixed
at 0.8 ms. The output refresh time would 2 Units x 18
µ
s per 16-point Output
Unit, or 0.16 ms. The Remote I/O servicing time would be as as follows for
the four 16-point I/O Units and four 32-point I/O Units controlled through the
Master:
16 points
(16 points x 4) + (32 points x 4)
x 20
µ
s = 1.24 ms
1 ms +
Calculations
Calculating Cycle Time
Section 6-2