User manual

IEC61131 User and Reference Manual
April 22, 2008
454
Physical Layer
The physical layer handles the physical media, such as serial or Ethernet, which DNP communicates.
Modbus Database Mapping
In SCADAPack controllers static DNP objects such as binary input, analog input, binary counter and
analog output are associated with Modbus registers. Whenever a DNP object is created an associated
Modbus register(s) is also assigned. Application programs executing in the SCADAPack controller,
C or logic, are able to assign physical I/O to Modbus registers using the TelePACE Register
Assignment or the ISaGRAF I/O Connection and these physical I/O points can then be assigned to
DNP objects. User application data such as runtimes, flow totals etc. may be also be assigned to
DNP objects.
This architecture enables DNP master stations and outstations to pass not only physical data points
between them but also to monitor and control user applications executing in the SCADAPack
controller. For example a master station can monitor a level in an outstation and then, based on the
application program, send a setpoint value to another outstation to control the level.
SCADAPack DNP Operation Modes
Within a DNP network, a SCADAPack controller can operate as a:
 DNP Outstation (Slave)
 DNP Master or Mimic Master or
 DNP Router
DNP Master Mimic and DNP Router are incompatible and mutually-exclusive modes of operation.
A DNP outstation forms the basic class of any DNP node in a network. All other operational modes
derive from a DNP Outstation. A DNP outstation responds to requests from one or more DNP
master stations on a network. Also, a DNP Outstation is able to initiate unsolicited responses
(messages) based on event data to a master station.
A DNP Master is capable of polling for data, accepting and processing unsolicited messages, and
sending control commands to an outstation. Note that a DNP Master can also act perform all the
duties of a DNP Outstation.
A SCADAPack controller acting as a DNP Router is simply acting a pass through, basically
redirecting messages from one DNP node to another. Similarly to a DNP Master, a DNP Router can
also perform all the duties of a DNP Outstation.
DNP Network topologies comprise several combinations of DNP Masters, DNP Routers, and DNP
Outstations. Typical configurations possible with SCADAPack controllers are:
 DNP Master and single DNP Outstation
 DNP Master and multi-dropped DNP Outstations
 DNP SCADA Host, Data Concentrator (Mimic Master) and multi-dropped DNP Outstations
 DNP SCADA Host, DNP Router and multi-dropped DNP Outstations
Major SCADAPack DNP operation modes are covered in the next chapters.