Reference
MVI56E-FLN ♦ ControlLogix Platform
User Manual
FA Control Network Ethernet Communication Module
Page 126 of 155
ProSoft Technology, Inc.
4.4.10 FA Link Protocol
In-Ring and Out-Ring Management
In-ring and out-ring of other nodes
At network initialization, each node monitors the line until the joining token
detection time is up. If the node monitors token flow, the node considers it as a
halfway participation state and performs the processing of (1) below. In the other
case, if the node does not monitor any token, the node considers itself as a
network start-up state and performs the processing of (2) below.
1 When monitoring a token flow (halfway participation state)
When monitoring a token flow within the joining token detection time, it is
recognized that a link is already established.
At this time, the node waits for transmission of a participation request frame
until the token is circulated 3 times. In this period, a node number conflict
check and an address overlapping check of common memory are made by
the received frames and the participating node management table is updated.
If any address overlapping is detected, the node set the common memory top
address and data size of areas 1 and 2 to 0 and shall not transmit cyclic data.
At the same time, the node sets the address overlapping flag, and resets the
common memory data validity flag.
When no error is found in node number, the node will send out a participation
request frame after the participation request frame transmission waiting time
is up. The participation request frame is transmitted regardless of token
holding.
A node that has recognized a node number conflict does not transmit a
participation request frame and does not join the network. The node number
conflict error shall be notified to the upper layer.
When a token for the self-node is not received after the third circulation
though the node joined the network by the participation request frame, this
node transmits a participation request frame again. Token monitoring is
performed for the joining token detection time. When a token is received, the
node is put into a halfway participation status. When no token is received, it is
put into a network startup status that will be described later.
2 When receiving no token (network startup status)
When no token is monitored during the joining token detection time, the node
transmits a trigger frame after the remainder of (node number / 8) x 4
milliseconds. If a trigger frame is received before the node transmits its
trigger frame, the node shall transmit no trigger frame.
When the participation request frame transmission waiting time (node number
x 4 milliseconds) is up after a first trigger frame reception, each node
transmits its participation request frame.
During the participation request frame reception waiting time (1200
milliseconds) after a first trigger frame reception, a conflict check of node
number and an address overlapping check are made and the participating
node management table is updated, thus each node shall wait for all nodes to
transmit participation request frames.
