IDEC WindSRV - Manual (Page 69)

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KEPServerEX5 Help
connect, the server will create a virtual tag for that location and will start scanning for data automatically.
To specify an optional data type, append one of the following strings after the '@' symbol:
 Byte
 Char
 Short
 Word
 Long
 DWord
 Float
 Double
 BCD
 LBCD
 String
If the data type is omitted, the driver will choose a default data type based on the device and address that is being
references. The default data types for all locations are documented in each individual driver's help documentation. If
the data type specified is not valid for the device location, the server will not accept the tag and an error will be posted
in the Event Log window.
OPC Client Using Dynamic Addressing Example
Scan the 16-bit location 'R0001' on the Simulator device. The following Dynamic Tag examples assume that the project
created is part of the example.
1. Start the OPC client application and connect to the server.
2. Using the Simulator driver, create a channel and name it Channel1. Then, make a device and name it Device1.
3. In the client application, define an item name as Channel1.Device1.R0001@Short.
4. The client project will automatically start receiving data. The default data type for address R0001 in the Simulator
device is Word. To override this, the @Short has been appended to select a data type of Short.
Note: When utilizing Dynamic Tags in an OPC client application, the use of the @[Data Type] modifier is not normally
required. OPC clients can specify the desired data type as part of the request when registering a link for a specific data
item. The data type specified by the OPC client will be used if it is supported by the communications driver. The @[Data
Type] modifier can be useful when ensuring that a communications driver interprets a piece of data exactly as needed.
Non-OPC Client Example
Non-OPC clients can override the update rate on a per-tag basis by appending @[Update Rate].
For example, appending <DDE service name>|_ddedata!Device1.R0001@500 will override just the update rate.
<DDE service name>|_ddedata!Device1.R0001@500,Short will override both update rate and data type.
See Also:
Static Tags (User-Defined) and Designing a Project: Adding User-Defined Tags .
Note 1: For every device in a project that can be used by a client to determine whether a device is functioning
properly, the server creates a special Boolean tag. To use this tag, specify the item in the link as Error. The value of
this tag is zero if the device is communicating properly; otherwise, it is one.
Note 2: If device address is used as the item of an link such that the address matches the name of a user-defined tag
in the server, the link will reference the address pointed to by the user-defined tag.
Note 3: Static Tags must be used in order to scale data in the server.
Static Tags (User-Defined)
The most common method that uses the server to get data from the device to the client application has two
requirements. Users must first define a set of tags in the server project and then use the assigned tag name as the
item of each link between the client and the server. The primary benefit to using this method is that all user-defined
tags are available for browsing within most OPC clients. Before deciding whether or not to create Static Tags, ensure
that the client can browse or import tags from the server.