Omron CJ1W-FLN22, Operation Manual, Page: 160 / 277

Network Communications System Section 8-1
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8-1 Network Communications System
FL-net is a token-based network. The token, or right to transmit, circulates
around the network and the node holding the token has the right to transmit. If
that node has data to send, it attaches the data to the token. If it has no data
to send, it simply passes the token along.
8-2 Communications Cycle Time
This section describes the method used to calculate the standard communi-
cations cycle time.
Calculating the
Communications Cycle
Time The communications cycle time (T) is the sum total of the token holding time
for each node in the network. Use the following methods to calculate the token
holding time for each node and obtain the total value.
Calculating the Token
Holding Time The token holding time is the time from when the token is received at the local
node until the token is sent to the next node. The communications cycle time
is the sum total of the token holding time for each node in the network config-
uration.
Token holding time (
µ
s) at 10 Mbps
= Number of local node data link send words × 5.1
+ Number of local node data link send frames × Minimum allowable frame
interval (See note 1.) + 700
Token holding time (
µ
s) at 100 Mbps
= Number of local node data link send words × 3.16
+ Number of local node data link send frames × Minimum allowable frame
interval (See note 1.) + 400
Set a minimum allowable frame interval of at least 1 ms when using a baud
rate of 100 Mbps. Use at least 1 ms when calculating the cycle time.For
details on standard set values, refer to
4-4-9 Total Number of Receive Errors
(FL-net Unit to CPU Unit) .
Note 1. Number of local node data link send frames:
When the local node data link send words (total of Area 1 and Area 2) ex-
ceeds 512 words, the data will be split into several frames.
Number of local node data link send frames = Number of local node data
link send words
÷
512 (rounded up to nearest integer)
Any decimal places are rounded up to the nearest integer. Therefore, if the
Passes token to next node.
Node 2
Node 3
Passes token to the node with the lowest number.
Node 1
Node N
Node N-1