Overview
The Alias Group object allows custom item names 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, 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). Server level alias groups are created on the Aliasing tab of the $Server object.
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Using the same example as above, an alias name at the device/protocol level 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, with the modifier will be appended to the item name and NOT the alias name. 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}’. For more information on item scaling, please see Item Scaling section.
Configuration
General Tab
See General Object Configuration page.
Alias Records
Activate Tags
The Activate Tags checkbox allows group tags to activate internally without waiting for a client to connect and activate them. Selecting this option will 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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