Hitachi FL.NET User Manual page 227

8 APPENDIXES
Node monitoring started
(when the power is turned
ON or a reset is performed)
Node 1
Enter token detection time (3 s)
Node 2
Node 3
Node 254
(b) Midway enter
If a node receives the token within the enter token detection time, it concludes that a link
is already established, and does not transmit an enter request frame until the token makes
three rounds. A frame received during such an interval is used to check for node
number, address, and other duplications and update the entering node management table.
If an address duplication is detected in such an instance, the common memory starting
address and common memory size of area 1 and 2 are set to 0 and cyclic data transmission
does not take place. When a node recognizes an address duplication, it sets an address
multiplexing flag and resets the common memory data validity notification flag. If the
node number is normal, the node transmits an enter request frame after an elapse of the
enter request frame transmission wait time. The enter request frame is sent no matter
whether the token is held.
not transmit an enter request frame and refrains from entering in the network.
Enter request frame transmission
wait time (node number × 4 ms)
Figure 8-7 Startup Timing Diagram 1
When a node recognizes a node number duplication, it does
Trigger Enter request
frame
Enter request frame reception wait
time (1.2 s)
8-14
Token