ProSoft Technology MVI69-FLN - Manual (Page 99)

Reference MVI69-FLN ♦ CompactLogix Platform
FA Control Network Communication Module
ProSoft Technology, Inc. Page 99 of 137
November 3, 2008
3.4.6 Allowable refresh cycle time
Each node always monitors the message frames in the network in the period
from receipt of a token until receipt of the next token to the node. If there is no
message frame in the network in this 1 cycle, this cycle time × 1.2 is specified as
the allowable refresh cycle time.
When the network is started, the allowable refresh cycle time is set to "0". When
a token directed to the node is received 3 times at the start-up, a refresh cycle
measurement will be started. Accordingly, the network does not perform
message transmission before a token is circulated once.
A node that joins in the halfway participation status, starts measuring the refresh
cycle time after the third token reception to the node.
The allowable refresh cycle time is dynamically determined depending on the
number of nodes joining the network.
3.4.7 Memory Resources
The module provides 8700 words for shared Area1 and Area2 common memory.
3.5 FL-net Protocol and network
3.5.1 Understanding the Basics of FL-net
The MVI69-FLN module is equipped to use with 10Base-T FL-net (Version 2.00)
Systems.
The basic configuration of a 10Base-T FL-net System consists of one hub to
which nodes are attached in star form through twisted-pair cable.
Number of Connectable Nodes and Node Numbers
Up to 254 nodes can be connected to an FL-net network. Each node is assigned
a node number from 1 to 254.
Node number Applications
1 to 249 Used for standard FL-net (Version 2.00) devices.
250 to 254 Used for FL-net (Version 2.00) maintenance purposes.
255 Reserved for internal system use. (used for broadcasting not available to
users)
0 Reserved for internal system use.