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OPC Specific Properties
OPC Specific Properties
OPC Specific Properties
PropID
Description
1
“Item Canonical DataType”
The data type of the item as stored on the OPC server. This
property is also exposed in the CanonicalDataType property of
the daitem object.
2
“Item Value”
The value that was last obtained from the OPC server for the item.
This property is the same as the Value property of the daitem
object. Querying this property behaves like a read operation from
the device.
3
“Item Quality”
The quality of the item's Value property. This property is the
same as the Quality property of the daitem object. Querying this
property behaves like a read operation from the device.
4
“Item Timestamp”
The time that the Value and Quality was obtained by the device
(if this is available) or the time the server updated or validated the
Value and Quality in its cache. This property is the same as the
TimeStamp property of the daitem object. Querying this property
behaves like a read operation from the device.
5
“Item Access Rights”
The ability of the server to read or write data to this item.
6
“Server Scan Rate”
Represents the fastest rate at which the server could obtain
data from the underlying data source. The accuracy of this value
could be affected by system load and other factors, and is not a
guaranteed rate.
7-99
Reserved for future use
B-3