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The maximum response time occurs when the input just misses the program
execution portion of the scan, meaning that processing must wait for the next
transmission and then the next (i.e., the fourth) scan.
Time = Input ON delay + cycle time × 4 + output ON delay
Cycle time > Remote I/O transmission times
Note Use the maximum cycle time output to AR 26 in computing the maximum I/O re-
sponse time.
Cycle time
CPU Unit
Master
Slave
Input
Output
Program execution
Transfer to CPU Unit
Transfer to MasterSlave I/O refresh
Example Calculations Calculations would be as shown below for an input ON delay of 1.5 ms, an out-
put ON delay of 15 ms, and a cycle time of 20 ms.
Minimum I/O Response Time
Time = 1.5 ms + (20 ms × 3) + 15 ms = 76.5 ms
Maximum I/O Response Time
Time = 1.5 ms + (20 ms × 4) + 15 ms = 96.5 ms
Note 1. The cycle time may be less than or equal to the remote I/O transmission time
when there are Special I/O Units on Slave Racks. If this is the case, there
may be cycles when I/O is not refreshed between the Master and the
C200HX/HG/HE CPU Unit.
2. Refreshing is performed for Masters only once per cycle, and then only after
confirming completion of the remote cycle.
3. The short duration of ON/OFF status produced by differentiated instructions
can cause inaccurate signals when dealing with Remote I/O Systems un-
less appropriate programming steps are taken.
Maximum I/O Response
Time
I/O Response Time Section 6-4