Figure 5-10. Modbus Plus Token Rotation Explanation; Figure 5-11. Modbus Plus Network Topology - ABB TPU2000 Technical Manual

Modbus Plus allows interconnection of up to 5 networks of devices.
comprised of up to 64 nodes of IED's distributed over 6000 feet of cable. Physical interface cabling is discussed in
other sections of this document. Each network is interconnected with a bridge device. The Modbus Plus Bridge
is obtainable through Schneider Electric or Square D Company. The Modbus Plus Bridge is an addressable
device with each port being assigned an address particular to the network to which it is attached. Figure 5-11
illustrates the network configuration.
Node 1 Node 2
Understanding the concept of Modbus Plus Paths is critical for assignment of a node address and calculating
network throughput. Figure 5-12 illustrates the maximum path implementation for Modbus Plus. The maximum
path implementation for a Modbus Plus Node is shown in Figure
5-12.
8 Program Master Paths (Programmable Logic Controller Only)
Used by Programmable Logic controllers to Transfer Master Data From Node to Node
(Unavailable to Modconnect Partner IED's)
8 Program Slave Paths (Programmable Logic Controller Only)
Used by Programmable Logic controller to Receive Master Data From Node to Node (Unavailable
to Modconnect Partner IED's)
8 Data Slave Paths
Used by Nodes to Receive Slave Data (Available to Modconnect Partner IED's)
8 Data Master Paths
Used by Slave Nodes to Transmit Slave Data to other Nodes (Available to Modconnect Partner
IED's)
1 Global Input Data Path
Global Data Path to Receive Global Data from Other Modbus Plus Nodes (Available to
Modconnect Partner IED's)
1 Global Output Data Path
Global Data Path to allow the node to Transmit Global Data to other Modbus Plus Nodes
(Available to Modconnect Partner IED's)
Global Data is a Modbus Plus capability allowing each node to place up to 32 – 16 bit words of data on the
network. Each word of Global Data is retrievable by any node on that segment of the Modbus Plus Network.
GLOBAL DATA IS NOT RETRIEVABLE THROUGH A MODBUS PLUS BRIDGE OR BRIDGE MULTIPLEXER
DEVICE.
TPU2000/2000R Modbus/Modbus Plus Automation Guide
1 3
2 4
55 56 57 58

Figure 5-10. Modbus Plus Token Rotation Explanation

Node 63 Node 64
Copper Cable or Fiber Optic *
TYPICAL NETWORK

Figure 5-11. Modbus Plus Network Topology

When the token has been passed
5
through all nodes on the network,
one token rotation has occurred.
This is a measurable and
deterministic time slice.
64
Network 1 Network 2
Network 4 Network 5
MAXIMUM IMPLEMENTATION
Each Modbus Plus network may be
Network 3
43