Omron CJ1W-FLN22, Operation Manual, Page: 161 / 277

135
Communications Cycle Time Section 8-2
number of local node data link send words is 768 words, 768
÷
512 = 1.5,
which is rounded up to 2 (frames).
2. Of the nodes in the network, the node with the highest value for the mini-
mum allowable
frame interval is used as the network’s minimum allowable
frame interval.
3. The token holding time when using message communications is calculated
as follows:
10 Mbps: Number of send message words × 1.6 + minimum frame interval
100 Mbps: Number of send message words × 0.16 + minimum frame inter-
val
4. Obtain the communications cycle time for networks that include units by
other manufacturers by calculating the total sum of holding time. For infor-
mation on non-OMRON units, refer to the relevant manuals for the unit.
5. The equation for calculating the communications cycle provides a rough
guide only. The actual communications cycle is affected by delays at the
hubs and other factors.
Token Holding Time Calculation Example
This example is calculated using the following conditions.
Example 1:
Baud rate: 10 Mbps
Number of participating nodes: 10 nodes
Total number of data link words: 680 words (68 words per node)
Minimum allowable frame interval: 100
µ
s
Message communications: None
Token holding time (
µ
s)
= 68 × 5.1
+ 1 × 100
+ 700
= 1146.8 (
µ
s)
= 1.2 ms
The number of participating nodes is 10 nodes, so the communications cycle
time is calculated as 12 ms (1.2 × 10).
Example 2:
Baud rate: 100 Mbps
Number of participating nodes: 10 nodes
Total number of data link words: 6,000 words (600 words per node)
Minimum allowable frame interval: 1 ms
Message communications: None
Token holding time (
µ
s)
= 600 × 3.16
+ 2 × 1000
+ 400
= 4296 (
µ
s)
= 4.3 ms
The number of participating nodes is 10 nodes, so the communications cycle
time is calculated as 43 ms (4.3 × 10).
Note This calculation example is for a network configuration in which each node is
allocated a uniform number of data link send words. WHen the number of data
link send words is different for each node, obtain the sum total of the token
holding time for each node (= communications cycle time).