Attributes; General Information About Attributes; Dnp Serial Slave Opc Client Attributes - ABB COM600 Series User Manual

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5.4.
5.4.1.
5.4.2.
COM600 series, Version 5.0
DNP 3.0 Serial Slave (OPC) User's Manual

Attributes

General information about attributes

In addition to item tags for process data (indications and commands), the OPC servers
and clients also provide some item tags for controlling the devices and retrieving status
information from them. These item tags are called attributes.
There are three categories of attributes: DNP Serial Slave OPC Client attributes, DNP
Serial Channel attributes and DNP Serial IED attributes. These attributes are described
in the following subsections.
The attributes are not updated automatically by the server according to the update rate
of the OPC group. Instead, it is required that the client explicitly refreshes the group or
requests a read of single attributes to retrieve the latest values. This does not matter for
most attributes, since they do not change value spontaneously. The exceptions are the
diagnostic counters and object status attributes. Object status attributes are updated
automatically by system messages, so in practice only diagnostic counters are affected
by this rule. It was introduced to avoid overloading the communication link between the
protocol stack and OPC server.

DNP Serial Slave OPC Client attributes

Table 5.4.2-1 DNP Serial Slave OPC Client attributes
Property / Para- Value or Value range/ Default
meter
Protocol Stack Ver- Value: Version information
sion
Description
Data type: Text
Access: Read-only
The version information of the Protocol
Stack.
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