ProSoft Technology MVI71-DNP - Manual (Page 92)

MVI71-DNP ♦ PLC Platform Reference
DNP 3.0 Master/Slave Communication Module
Page 92 of 172 ProSoft Technology, Inc.
August 23, 2007
Step Description
1 The DNP slave port driver receives the configuration information from the DNP.CFG
file. This information configures the serial port and define the slave node characteristics.
Additionally, the configuration information contains data that can be used to offset data
in the database to addresses requested in messages received from master units.
2 A Host device (DNP Master unit) issues a read or write command to the module's node
address. The port driver qualifies the message before accepting it into the module.
3 After the module accepts the command, the data is immediately transferred to or from
the appropriate internal database in the module. If the command is a read command,
the data is read out of the database and a response message is built. If the command is
a write command, the data is written directly into the database and a response message
is built.
4 After the data processing has been completed in Step 3, the response is issued to the
originating master node.
5 Counters are available in the Status Block that permit the ladder logic program to
determine the level of activity of the Slave Driver.
Review the Installing and Configuring the Module section for a complete list of
the parameters that must be defined for a slave port. The response messages
from the slave driver include an IIN (internal indication word) defined in the
Reference chapter – Internal Indication Word.
The slave driver supports object 110 (octet string data). Four points are pre-
assigned values as defined in the following table.
Point # Description
0 Module Name as assigned in configuration file.
1 Product Name
2 Version Information in format: wwww xxxx yyyy zzzz Where wwww is product
code, xxxx is the revision, yyyy is the operating system number, and zzzz is the
run number.
3 Manufacturer name for module.
The variation used in the request message determines the length of the string
returned for each point. The maximum string length used by the module is 100.