Allen-Bradley 1756-CNB - Page 37

Publication 1756-UM523F-EN-P - December 2006
Design the System 37
Do the redundant chassis use more than 1 ControlNet
network?
• Yes — See page 29.
• No — Skip this guideline.
The NUT of each network must be within the values indicated on page 29. If
you use a larger network update time (NUT), the controller could lose its
connection with a module during a switchover. This could cause outputs to
change state.
Example
Guideline Details
If the NUT of this network is 5 ms…
ControlNet
Network 1
Then the NUT of this network must be
21 ms or less.
ControlNet
Network 2
If the smallest
NUT on a network
is (ms)
Then the largest NUT on any other
network must be less than or equal
to (ms)
215
317
419
521
623
725
827
929
10 31
11 33
12 35
13 37
14 39
15 41
16 43
17 46
18 48
19 50
20 52
21 55
22 57
23 59
24 62
25 64
26 66
27 68
28 71
29 73
30 75
31 78
32 80
33 82
34 84
35 87
36 89
37...90 90
If the smallest
NUT on a network
is (ms)
Then the largest NUT on any other
network must be less than or equal
to (ms)