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)
(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
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.
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”.