Appendix A
AĆ6
Figure A.2
PLC
Ć
2/30 Local Sys
t
em Example
PLC–2/30
1
7
7
1
A
L
1
7
7
1
D
E
Rack 1
1
7
7
1
A
L
1
7
7
1
D
E
Rack 3
1
7
7
1
A
L
1
7
7
1
D
E
Rack 4
1
7
7
1
A
L
1
7
7
1
D
E
Rack 2
10813-I
Solution:
Program length = 4K words
Number of chassis = 4 (1 assigned rack number per chassis)
Number of block-transfer words, W = 2 (read) or 20 (write)
1.
Calculate the system values.
Processor Scan Time (PS) = (5 ms/1K words) x (4K words) = 20
ms
