====Control Module====

The **Control** [[analytic_modules|module]] is used to perform simple tests to see if an asset is either //In Control// (near the expected values) or //Out Of Control// (outside the expected values).

It is very similar to the [[module_limits|Limit]] module, except for the fact that the Control module takes a single //target// and a //span//, while the Limit module takes an //upper threshold// and and //lower threshold// instead.

The analytic returns a list of time-frames, and the assets status (Under Control or Out Of Control) during those time-frames.

===Starting Out===

When you first create a new Control analytic, you'll see the graph below...

{{control_start.png}}

The node in the middle is the [[control_control|Control]] node, which takes the //measured//, //target// and //tolerance// values and determines if the current inputs look like they are close to target.

The //tolerance// value is the amount the actual value is allowed to drift from the target. For example, if there was a target of 20 and a tolerance of 2, a value of 24 would be considered //uncontrolled// because it's more than 2 units away from the target.

On the right is the [[control_output|Control Output]] node - if the value going into this is **true**, the analytic considers you out of control. If it's **false**, you're in control.

===Why Two Nodes?===

There are a number of reasons why control can //deliberately// drift outside the expected range, such as when the system is shut down, running manually, or in the middle of preparing for a new or different batch of product.

The gap between the 'control' node and the 'Out Of Control' node is where you can add any of this additional logic. 

You can also add [[timing_timer|Timers]] to your graph if you want to delay things. Ensuring that it stays out of control for more than 5 seconds can help deal with sudden spikes, inrushes or sensor issues. 

===Module-Specific Nodes===

[[control_control|Control]] \\
[[control_output|Control Output]]

===Examples===

[[example_control_basic|Time Spent Out Of Control]]