Rockwell Automation 1761-NET-DNI DeviceNet Interface (DNI) User Manual

Page 20

Publication 1761-UM005B-EN-P - October 2006

20 Operation

Programmable Controller Communications Commands (PCCC)
DeviceNet Messaging/ DF1 (peer-to-peer)

Allen-Bradley controllers with RS-232 ports communicate via PCCC
messaging. The DNI encapsulates the PCCC messages to allow PCCC
messaging to operate over DeviceNet. This is an open,
non-proprietary protocol that can be implemented by anyone who
needs to exchange information with an Allen-Bradley controller.

The DNI is capable of receiving the DF1 protocol, and sending or
receiving it over DeviceNet. This enables any existing Allen-Bradley
device that is capable of DF1 communications to an Allen-Bradley
controller to use the DNI to communicate over DeviceNet.

For DNI Series A, the only stipulation is that the device has to be
capable of entering a destination node address (For DNI Series B, this
stipulation has been removed with the addition of the DF1 Substitute
Address parameter.). The DNI uses the DF1 destination node address
that is embedded in the DF1 packet to determine where on DeviceNet
it needs to send the information.

This DF1-to-DeviceNet capability lets you configure a peer-to-peer
network. By programming standard ladder logic message instructions,
with the destination address the same as the destination DNI (when
not using DNI Series B address substitution), the message is routed
across DeviceNet by the DNI. The following diagram illustrates the
types of messaging.

Messaging Overview

Also see Explicit Messaging (DNI Series B only) on page 80 for DNI
Series B.

KFD

Running RSLogix 500
and/or DeviceNet
Manager

IBM Compatible

Node 2

Node 1

DNI Module

Master/Slave I/O

Peer-to-Peer Messaging

DeviceNet Network

Node 3

SLC
Rack

1747-
S