Rockwell Automation 1761-NET-DNI DeviceNet Interface (DNI) - Manual (Page 17)

17 Publication 1761-UM005B-EN-P - October 2006
Chapter
3
Operation
Modes of Use The DeviceNet Interface has three primary features.
• DeviceNet I/O
• Explicit Messaging
• Programming over DeviceNet network
DeviceNet I/O
The DNI is capable of being owned by a master on DeviceNet. This
functionality on DeviceNet is part of the I/O class of services, and
allows a master device to exclusively manage (own) another device’s
(a different node number) data and resources. This type of
relationship is functionally the same as a PLC with remote I/O. A PLC
uses the remote I/O chassis as distributed inputs and outputs. The
master/slave relationship on DeviceNet is exactly the same, except it
is being done over DeviceNet.
The amount of data available between devices that implement I/O
master/slave services is determined by the design of each device, and
is not a function of DeviceNet.
The DNI on DeviceNet is capable of handling 32 I/O words of data
with a DeviceNet I/O master for DNI Series A (64 for DNI Series B).
This is broken up into two data images: the input image and the
output image.
IMPORTANT
All input and output comments are referenced from
the perspective of the DeviceNet Master.