External Item Data Transfer Control

This feature makes it possible to control when an external item’s value shall be transferred to another item. It may not always be the case that we want the value to be transferred regardless of the value. Here we may select between different rules for when a transfer should be carried out depending on the external item value. In addition we may set up the system such that the value is transferred from different external items depending on the value of a third item (MUX).

The following item attributes must be specified:

Attribute ID Name Description Type
5980 ExtTransferCtrlMethod The control method that decides when external items are transferred to the item of the attribute. One of the following may be selected:
Name Meaning Value
always Always transfer external item values 0
when CtrlItem changes from zero Transfer once when control item (ExtTransferCtrlItem) value changes from 0 1
when CtrlItem is zero Transfer when control item (ExtTransferCtrlItem) value = 0 2
when CtrlItem is non zero Transfer once when control item (ExtTransferCtrlItem) value  is != 0 3
when CtrlItem becomes > argument Transfer once when control item (ExtTransferCtrlItem) value becomes greater than argument value (ExtTransferCtrlArgument) 10
when CtrlItem becomes < argument Transfer once when control item (ExtTransferCtrlItem) value becomes less than argument value (ExtTransferCtrlArgument) 11
when CtrlItem becomes = argument Transfer once when control item (ExtTransferCtrlItem) value becomes equal argument value (ExtTransferCtrlArgument) 12
when CtrlItem becomes <> argument Transfer once when control item (ExtTransferCtrlItem) value becomes different argument value (ExtTransferCtrlArgument) 13
when CtrlItem > argument Transfer once when control item (ExtTransferCtrlItem) value is greater than argument value (ExtTransferCtrlArgument) 20
when CtrlItem < argument Transfer once when control item (ExtTransferCtrlItem) value is less than argument value (ExtTransferCtrlArgument) 21
when CtrlItem = argument Transfer once when control item (ExtTransferCtrlItem) value is equal to argument value (ExtTransferCtrlArgument) 22
when CtrlItem <> argument Transfer once when control item (ExtTransferCtrlItem) value is different from argument value (ExtTransferCtrlArgument) 23
2 byte unsigned integer
5982 ExtTransferCtrlItem The Item ID of another item, whose value will control the transfer of external item values to this item string
5984 ExtTransferCtrlArgument The argument to use with the ExtTransferCtrlMethod string
5986 ExtTransferCtrlInhibitQuality (Note that not all item-types will have this functionality implemented) The quality to set when external item value transfer is inhibited, as a result of the chosen ExtTransferCtrlMethod. When other than none, data is still transferred during control method failure.
When none, data transfer stops during control method failure. The attribute is enumerated, with the following options:
Name Meaning Value
none Quality is not set/altered upon control method failure, but data transfer is inhibited 0
quality: bad Quality is set to this value upon control method failure, but data is still transferred 65536
quality: uncertain Quality is set to this value upon control method failure, but data is still transferred 65600
quality: good Quality is set to this value upon control method failure, but data is still transferred 65728
quality: bad:config error Quality is set to this value upon control method failure, but data is still transferred 65540
quality: bad:not connected Quality is set to this value upon control method failure, but data is still transferred 65544
quality: bad:device failure Quality is set to this value upon control method failure, but data is still transferred 65548
quality: bad:sensor failure Quality is set to this value upon control method failure, but data is still transferred 65552
quality: bad:last known value Quality is set to this value upon control method failure, but data is still transferred 65556
quality: bad:comm failure Quality is set to this value upon control method failure, but data is still transferred 65560
quality: bad:out of service Quality is set to this value upon control method failure, but data is still transferred 65564
quality: bad:waiting for initial data Quality is set to this value upon control method failure, but data is still transferred 65568
quality: uncertain:last usable Quality is set to this value upon control method failure, but data is still transferred 65604
quality: uncertain:sensor not accurate Quality is set to this value upon control method failure, but data is still transferred 65616
quality: uncertain:engineering units exceeded Quality is set to this value upon control method failure, but data is still transferred 65620
quality: uncertain:sub normal Quality is set to this value upon control method failure, but data is still transferred 65624
quality: good:local override Quality is set to this value upon control method failure, but data is still transferred 65752
4 byte unsigned integer

*** Note: *** The module property ExtItemCalculationSequence is important in data validation and transfer. It decides whether data validation or data transfer will be performed first in the external item manager. Available values: TransferBeforeValidation, ValidationBeforeTransfer.

Alternatively

ExtItemOverrideMethod. This attribute decides what method to use when assigning a value from an external item. One of the following may be selected: “Default” or “Assign complete value from external item”.