Klinkmann Automation Omron Ethernet DAServer | 49 |
device groups with a zero update interval (manual protocol triggering).
Generic OPC Syntax
DAServer serves as a container for the OPC Groups, which provide the mechanism for containing and logically organizing OPC items. Within each OPC Group, an OPC- compliant client can register OPC items, which represent connections to data sources in the field device. In other words, all access to OPC items is maintained through the OPC Group.
The fully qualified name for an OPC item is called the Item ID (equivalent to Item Name). Generally, in OPC data acquisition DAServers, the syntax can be as follows:
AREA10.VESSEL1.TIC1.PLC.D100
where each component (delimited by a period) represents a branch or leaf of the field device’s hierarchy. In this example:
•PLC is the name of the target PLC.
•D100 is the specific data point (Item) desired.
•An item is typically a single value such as an analog, digital, or string value.
The syntax for specifying a unique Item ID is
Unit1.CV500.D100
Item ID describes the syntax for defining the desired data point, OPC provides for another parameter, called Access Path, that defines optional specifications for obtaining that data. In DAServers, Access Paths are equivalent to Device Groups; it is this parameter that is used to define the update interval between the DAServer and the field device for accessing the values of data points in the PLC.
Omron Ethernet DAServer Ver 1.x User Manual Rev 1.3 | 17014m13 |
