Allen-Bradley DeviceNet 1761-NET-DNI, User Manual, Page: 26 / 101

1761-6.5
3-4 Operation
PCCC (Programmable Controller Communications Commands)
DeviceNet Messaging/ DF1 (peer-to-peer)
PCCC messaging is how Allen-Bradley controllers (that have RS-232 ports)
have communicated for many years. 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 allows users to 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 different types of
messaging.
Also see Explicit Messaging (DNI Series B Only) on page 8-1 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