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8-4 Communication time
[1] Token round time
The token round time can be obtained as follows.
Node N 1
Spacing between data
of this node and the
previous node
Token round time = ∑
(Total of the space (time) between data from this node and all previous nodes.)
"Tn" varies with the amount of data sent by the previous station. It also varies with the processing timing
of the JW-50FL. To get the token round time, perform a calculation based on the rough numbers shown
below.
Cyclic transfer capacity per station (word)
Area 1
1
2
4
8
16
32
32
64
64
96
96
128
128
160
256
- The values above are for the JW-50FL. For other nodes, see each manual.
When message transfers are used, the communication time will be longer. However, the FL-net re-
stricts the token round time when using message transfers to 1.2 times that of a message transfer.
[2] Round time when a communication error occurs
If a station goes down, the node immediately after the dead node will issue a token. This time depends
on the token monitor time of the dead node. Therefore, if one station goes down, its cycle will result in a
longer token monitor time than the dead node would have used. If two consecutive nodes go down
simultaneously, the next node will issue a token. In this case the time required to issue a new token will
be the total of the token monitor time of both dead nodes. If more than two consecutive nodes go down,
a similar calculation will apply.
Node N
Tn
m
Tn
n=1
Area 2
1
2
64
128
256
464
512
960
1024
1440
1536
1920
2048
2560
4096
8-13
Chapter 8: Cyclic Transfer
Communication time
per station (ms)
1.2 to 1.7
1.3 to 1.7
1.5 to 1.9
1.7 to 2.3
2.2 to 3.0
3.0 to 4.2
3.6 to 4.3
4.2 to 6.1
5.0 to 6.7
5.1 to 8.1
6.5 to 9.0
6.8 to 10.1
8.0 to 10.6
8.6 to 13.3
13.9 to 18.4
8
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