Rockwell Automation 1761-NET-DNI DeviceNet Interface (DNI) - Manual (Page 77)

77 Publication 1761-UM005B-EN-P - October 2006
Chapter
8
Explicit Messaging (DNI Series B Only)
Explicit messaging is the mechanism that is used to move data over
the DeviceNet network. Every device on the DeviceNet network either
initiates or responds to some type of explicit message to either read
(get) or write (set) data.
In the network shown below, node 5 is a master (scanner) that owns
slave I/O data on the DeviceNet network. When the master interacts
with its slaves (either through strobed, polled, cyclic or COS
connections), the communications used are specific types of I/O
messages. If the MicroLogix controllers at nodes 10 and 30 want to
exchange data, they message through the DNIs to each other using
explicit messages.
The functionality of each device determines how it can interact with
other devices on the network. Many devices can respond only to
requests. Some devices can be configured to respond, but they can
also initiate messages to others. One example is the PanelView
operator interface that has DeviceNet technology built in. It can be
owned by a master as slave I/O, and can also get or set data to other
devices on the network.
Node 5
Node 15
Node 25
Node 30
Node 20
Node 10