Entering In/Leaving From Fl-Net - Hitachi FL.NET User Manual

8.2.2 Entering in/leaving from FL-net

(1) Entering in FL-net
When a node starts up, it monitors the line until an enter token detection timeout occurs. If
it does not receive the token in this instance, it concludes that the network startup process is
in progress, and then newly participates in the network. If it receives the token, on the other
hand, it concludes that it is in a midway enter state, and then participates in the network on
the spot.
(a) New enter
If a node does not receive the token within the enter token detection timeout period, the
node prepares for trigger transmission and then start a transmission after an elapse of
predetermined time which is determined by multiplying the remainder of node number/8
by 4 ms. If trigger reception occurs before trigger transmission, the node does not
transmit a trigger. For a period of enter request frame reception wait time (1,200 ms)
after trigger reception, all nodes wait to transmit an enter request frame while checking for
a duplicate node number or address and updating the entering node management table.
When the enter request frame transmission wait time (node number × 4 ms) elapses after
trigger reception, the nodes transmit an enter request frame. If a node recognizes a
duplicate address in accordance with an enter request frame of another node, the former
node sets the common memory starting address and common memory size for area 1 and
2 to 0 and does not transmit cyclic data. When a node recognizes a duplicate address, it
sets an address duplication flag and resets a common memory data validity notification
flag. When an enter request frame reception wait timeout occurs, a entering node having
the lowest node number transmits the token first in accordance with the entering node
management table. When a node recognizes a duplicate node number, it starts no
transmission/reception.
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8 APPENDIXES