Rockwell Automation 1771-QC , D17716.5.25 SER/B SERVO POS - Manual (Page 179)

Chapter 8
8Ć18
Figure 8.7
Nominal Time Table
1 2
3
4
1
2
4
3
40 52 58 54
67 76 68
99 98
123
Time (ms)
Active I/O channels
containing one or more block
transfer modules.
Number of Active I/O Channels
Step 2 Ć Determine a time from the table. Example values have been added.
Example:
Number of active I/O channels: 3
Number of active I/O channels
ccontaining one or more block
transfer module: 2
Time, from table: 68ms
3. Compute the approximate transfer time for each block-transfer I/O
channel. You will use a value from the table, values from your
diagram (Figure 8.6), and the formula (Figure 8.8).
Figure 8.8
Channel Time Computation
CT = Channel Time
CT = [Time] x [ # BT modules] + [# I/O chassis Ć1] x 9ms
(table)
Step 3 Ć Compute the scanner times for each block transfer channel. Example values have been added.
on BT channel
CT1
on BT channel
= [68] x [7] + [5 Ć1] x 9
= [68] x [7] + [4] x 9
= 476 + 36
= 512ms
CT2 = Not a block transfer channel
CT3 = [68] x [1] + [2 Ć 1] x 9
= [68] x [1] + 1 x 9
= 68 + 9
= 77ms
CT2 = Not an active channel
4. Compute the approximate read/write block transfer time for the
1771-M3 controller in channel 1 and in channel 3 (Figure 8.9).