Yaskawa VS-616G5 Modbus Plus Communication Card - Manual (Page 8)

1-4 Introducing the Modbus Plus Network
Point to Point Message Transactions
While a node holds the token, it may send application messages. If the node does not
have any messages to transmit, it will pass the token. Each message can contain up to
100 controller registers consisting of 16-bit words of data. The other node(s) monitor the
network for incoming messages.
When a node receives a message, it sends an immediate acknowledgment to the
originating node. If the message is a request for data, the receiving node will begin
assembling the requested data into a reply message. When the message is ready, it will
be transmitted to the requester when the node receives a subsequent token granting it
access to transmit. After a node sends all of its messages, the node passes the token to
the next node address in sequence.
The Yaskawa VS-616G5 drive is capable of participating as a node on a Modbus Plus
communications network.