Rockwell Automation 1771-DA,D17716.5.13 U MNL 1771-DA ASCII I/O MODULE - Manual (Page 204)

ASCII Module
PLC-2 Family Processors
Appendix A
AĆ36
Figure A.13
Nominal Time Table
Step 2 -Determine a time from the table. Example values have been added.
Active I/O channels
containing one or more
block transfer modules
1
1
2
3
4
2 3 4
40 52
67
54
68
98
58
76
99
123
Time (ms)
Number of active I/O channels: 3
Number of active I/O channels containing one or more
block transfer module: 2
Time, from table: 68ms
12829
Number of Active I/O Channels
3. Compute the approximate transfer time for each block transfer I/O
channel. Use values from your channel diagram (Figure A.12), a
value from the table (Figure A.13), and the formula from step 6
above. We make these calculations for you in Figure A.14.
Figure A.14
Computing Channel Times
Nominal
Time
x
#BT modules
on BT channel
+
#I/O chassis
on BT channel
-1
X 9
Step 3 - Compute the scanner time for each block transfer channel. Example values have been added.
CT = Channel Time
CT =
CT1 = [68ms] x [3] + [4-1] x 9ms
204ms + 3 x 9ms
231ms
CT2 = Not a block transfer channel
CT3 = [68ms] x [1] + [2-1} x 9ms
68ms + 9ms
77ms
CT4 = Not an active channel