Overview
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The Alias Group object allows custom item names
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to be linked to protocol item names. This is particularly useful with numeric item names.
Alias Items and Groups
To create an alias for use at the $Server level for register 5176 which is "Mass" for the Modbus Omni Protocol,
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the Alias Name would be entered as ‘ModbusOmniDevice.Mass’ (including the device name), and the corresponding item name would be entered as ‘ModbusOmniDevice.5176’ (also including the device name).
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Server level alias groups are created on the Aliasing tab of the $Server object.
An alias group can also be created for use with a single device or can be created for a group of devices of the same protocol if the tags are the same.
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| Alias item names at the device/protocol level MUST NOT include the device name, but only item name. |
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Using the same example as above, an alias name at the device/protocol level
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would be entered as ‘Mass’, and the corresponding item name would be entered as ‘5176’. An OPC Client that wanted the Mass value from the device named ModbusOmniDevice would use an OPC item named ‘ModbusOmniDevice.Mass’.
Item Modifiers
Item modifiers and item scaling can be used in alias groups,
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with the modifier will be appended to the item name and NOT the alias name.
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For example if the raw value returned for Mass is 2500 and the scaled value should be .25, the alias name might be entered as ‘Scaled Mass’ and the item name would be entered as ‘5176{SG:.001,0}’.
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For more information on item scaling, please see Item Scaling section.
Configuration
General Tab
See General Object Configuration page.
Alias Records
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Activate Tags
The Activate Tags checkbox allows group tags to activate internally without waiting for a client to connect and activate them.
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Selecting this option will
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enable ACM to poll all the items in the Alias group without the items being in an OPC Client.
Edit Records
Click the Edit Records button to open the Alias Record Collection dialog box to add the alias names and item names.
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Click
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Add to enter the appropriate number of New Record items.
Click Remove to delete any unwanted New Record items.
Click Tabular Display to view all New Record items at once.
Alias Name
The name by which the item will be referenced. Max Length: 255 characters.
Item Name
The item name of the point in the device. Modifiers and scaling can appended to the Item Name. Max Length: 255 characters.
Record Id
Used to describe this entry. Max Length: 50 characters.
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Click the Tabular Display button to view the record collection in a table.
On this page
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When record editing is complete, Click Close to return to the owning object type. Click the Save button |
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