Introduction

Transaction Groups are the heart of the SQL Bridge module. They are units of execution that perform a variety of actions, such as storing data historically, synchronizing database values to OPC, or loading recipe values. A variety of group types, items types, and options means that Transaction Groups can be configured to accomplish almost any task.

Transaction groups are edited through the Ignition designer. When a group is selected, you will be presented with the transaction group workspace.

1)	Title bar - Shows the name of the currently selected group, as well as options to set it as Enabled or Disable, and to Pause, if it's currently executing.

2)	Item configuration - Shows all of the items configured in the selected group. Many settings can be modified directly through the display, the rest by double-clicking the item, or selecting "edit" in the context menu.

3)	Action / Trigger / Options tabs - Define how and when a group executes. Holds most of the options that apply to the group in general, such as the update rate, and which data connection it uses.

4)	Status / Events tabs - Provides information about the executing group, including the most recent messages that have been generated.

In order for groups to be evaluated, they must first be enabled. This is done by selecting "enabled" in the group title bar, and then saving the project. The group executing can be stopped by reversing the procedure and selecting "disabled" before saving. If you want to quickly and temporarily stop the group's evaluation, toggle the "pause" button. This will prevent execution until the group is un-paused, or until the system is restarted.

Group settings may be modified at any time, regardless of whether or not the group is executing. Modifications will be applied when the project is saved, and the group will be started or stopped as required. Some changes such as modifying items may cause features like live values to appear to be incorrect. It is therefore important to note the modified icon that appears next to the group, and to save often. If you would prefer to stop the group before making edits you can simply pause the group. Execution will begin again after the project is saved.

Generally speaking, groups work on a timer. They are set to run at a certain rate, and at that rate, the check the rest of the settings. If the trigger conditions pass, the group is executed fully. The following section provides a fuller outline of the execution cycle.