Rockwell Automation FactoryTalk Transaction Manager User Guide - Manual (Page 104)

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FactoryTalk Transaction Manager User Guide
104
Bidirectional Transactions
Bidirectional transactions with input/output parameters are not complete
until the control connector acknowledges that the control system has
received the transaction output data. The transaction timeout includes the
time it takes for the data server to connect to the control system, write the
data values, and return a response to the control connector. Transactions
with outputs may have latency in both the enterprise connector and the
control connector.
Transactions With Bound Transaction Results
Bidirectional transactions that use the Transaction Result Binding are not
complete until the Transaction Control Manager service or FactoryTalk
Transaction Manager service receives a reply from the control connector
that the bound result was written. If a transaction times out after the bind
transaction result is sent to the control connector, all data is moved
successfully to the controller and a message indicates that the transaction
failed.
Database Triggers
Database triggers are functions that are executed by the database whenever
the triggering operation occurs. For example, a trigger can be set so that
whenever a value is inserted into a table, the data is verified and then another
value is updated with the verified data. The amount of time necessary to
process the trigger and the associated function is charged against the
transaction timeout. In this case, the database insert does not return control
to the enterprise connector until the insert and it’s triggered function is
complete. In other words, a real-time transaction is considered complete
when the FactoryTalk Transaction Manager transaction, and any database
triggers that are caused by the transaction, are complete.
Expression Editor
An expression is a calculation or formula defined in the Expression Editor
using mathematical operators and functions that can be bound to a data