Filter
Top Products
RuggedRouter® User Guide
DNP (Distributed Network Protocol)
RuggedRouter supports DNP 3.0, commonly used by utilities in process automation
systems. DNP3 protocol messages specify source and destination addresses. A
destination address specifies which device should process the data, and the source
address specifies which device sent the message. Having both destination and source
addresses satisfies at least one requirement for peer-to-peer communication since the
receiver knows where to direct a response. Each device supporting the DNP protocol
must have a unique address within the collection of devices sending and receiving
DNP messages.
Address Learning for DNP
RuggedRouter implements both local and remote address learning for DNP.
A local Device Address Table is populated with DNP Addresses learned for local and
remote DNP devices. Each DNP address is associated with either a local serial port or
a remote IP address.
When a message with an unknown DNP source address is received on a local serial
port, the DNP source address and serial port number are entered into the Device
Address Table. When a message with an unknown DNP source address is received
from the IP network, on the IP interface that is configured as the DNP learning
interface, the DNP source address and the IP address of the sender are entered into the
Device Address Table.
When a message with an unknown DNP destination address is received on a local
serial port, the message is sent in a UDP broadcast out the network interface
configured as the DNP learning interface. When a message with an unknown DNP
destination address is received from the IP network, it is sent to all local serial ports
configured as DNP ports.
UDP transport is used during the DNP address learning phase.
All learned addresses will be kept in the Device Address Table, which is saved in
non-volatile memory, which makes it unnecessary to repeat the DNP address learning
process across a RuggedRouter reboot or accidental power loss.
An aging timer is maintained per DNP address in the table, and is reset whenever a
DNP message is sent to or received for the specified address.
This learning facility makes it possible to configure the DNP3 protocol with a
minimum number of parameters: a TCP/UDP port number, a learning network
interface and an aging timer.
DNP Broadcast Messages
DNP addresses 65521 through 65535 are reserved as DNP3 broadcast addresses.
RuggedRouter supports DNP3 broadcast messages. DNP broadcast messages received
on local serial ports are transmitted to all IP Addresses in the DNP Device Address
Table (whether learned or statically configured). When a DNP broadcast message is
received from the IP network, it is transmitted on all local serial ports configured as
DNP ports.
204 RuggedCom