User manual

IEC61131 User and Reference Manual
April 22, 2008
467
SCADAPack DNP Mimic Master
In a typical DNP network a SCADA Host master communicates with a number of outstations. The
SCADA Host will poll each outstation for data and may receive change event data in the form of
unsolicited responses from the outstations. This type of DNP network is shown in the following
diagram.
SCADAPack
DNP Outstation A
SCADAPack
DNP Outstation B
DNP SCADA Host
Figure 0-3: DNP SCADA Host and multi-dropped DNP Outstations
In the above configuration the SCADA Host manages the communication path with each outstation.
When the communication path is slow, such as with dial-up communication, or subject to high error
rates, such as with some radio communication, the data update rate at the SCADA host can become
very slow.
Adding a SCADAPack controller configured for Master Mimic Mode, allows for the SCADA Host
to poll the SCADAPack (Mimic Master) for all outstation data instead. In essence, the SCADAPack
Mimic Master is acting as a Data Concentrator, reporting on behalf of all the outstations currently
configured in its routing table. The following diagram shows the addition of the SCADAPack
Mimic Master.
SCADAPack Mimic
SCADAPack
DNP Outstation A
SCADAPack
DNP Outstation B
DNP SCADA Host
Slave Master
Figure 0-4: SCADAPack Mimic Master and multi-dropped DNP Outstations
In this configuration the outstation side of the network has been decoupled from the host side of the
network, as the SCADAPack mimic master now manages all the communication with the
outstations.
The SCADA Host and all outstations will typically be connected to different communication ports of
the SCADAPack Mimic Master. The mimic will respond to the following DNP messages on behalf
of the targeted station:
 Read messages (this includes class polls as well as individual point reads) from SCADA Host
 Write messages from SCADA Host
 Unsolicited messages from an outstation