Logic Viewer and Editor widget - Metasys - LIT-12012116 - Server - Metasys UI - 7.0

What is the Logic Viewer and Editor widget?

This widget provides a single view of Logic Connection Tool (LCT) logic diagrams in Metasys UI and JCT. LCT logic is required to control certain aspects of a Building Automation System (BAS). Program (Control System) objects are often used to create supervisory control logic to comply with the sequence of operations called out in project plans, specifications, or contract documents for various systems in a BAS.

The widget consists of a viewing component, hereafter called Logic Viewer, and an editing component, hereafter called Logic Editor.

The Logic Viewer provides a visual representation of supervisory LCT logic for you to understand, trace, and troubleshoot logic in the Metasys system. The Logic Editor provides the functionality to create new logic and edit existing logic.

Who can access the Logic Viewer and Editor? Who can modify logic diagrams?

You do not require special authorization or licensing to access the Logic Viewer and Editor and to modify logic diagrams.

How do I access the Logic Viewer and Editor?

What is the layout of the Logic Viewer and Editor?

The following figures and tables describe the layout of the Logic Viewer and the Logic Editor.

Note: The live values shown in the following figure appear only in the Logic Viewer in Metasys UI. JCT does not show live values.

Figure 1. Logic Viewer layout

Table 1. Logic Viewer layout

Number	Name	Description
1	Main display	Provides a single view of the logic diagram. The diagram displays live values in Metasys UI and not in JCT.
2	Export	Exports the logic diagram in PDF format.
3	Edit	Click to open the Logic Editor.
4	Select	Select an element of the logic diagram and navigate to it.
5	Pan	Move the entire logic diagram.
6	Zoom In	Zoom in to the logic diagram. You can also move the wheel button on your mouse to zoom in.
7	Zoom Reset	Zoom Reset fits a logic diagram in the main display. The zoom level is adjusted based on the content of the logic diagram.
8	Zoom Out	Zoom out of the logic diagram. You can also move the wheel button on your mouse to zoom out.
9	Reference block example	Input Reference blocks and Output Reference blocks provide information and links for their referenced object and configured attribute. See the following figures.

Figure 2. Input Reference block with connection line shown

Figure 3. Output Reference block with connection line hidden

Table 2. Input Reference block and Output Reference block callouts

Number	Name	Description
1	Global status indicator icon	Appears when live values are shown. Displays the same global status indicator icon as appears in the Network tree and Views for the referenced object.
2	Object type icon	Displays the object type icon for the referenced object.
3	Referenced object	Identifies the referenced object by displaying its name or item reference as a link to the object.
4	Trigger icon	Applies to only Input Reference blocks. A star icon appears when the block is configured with Trigger selected.
5	Connection value and priority	When live values are shown, the connection value displays near the starting connection point. For hidden connections, the value also displays at the ending connection point. For priority connections, the configured priority displays at the ending connection point. For hidden connections, the priority also displays at the starting connection point. Note: Comparing the connection value and priority to the current value shown in an Output Reference block can help you identify cases where the logic is currently not in control. For example, in the previous figure, you can see that an Operator Override is controlling the referenced object, and as a result, the lower priority value from the logic cannot take effect.
6	Information icon	When clicked, displays a tooltip with additional information and links for the referenced object, such as the configured attribute and the item reference. For server sites that have Spaces and Equipment defined, the tooltip also includes space and equipment information.
7	Status color bars	Appears only when live values are shown. Displays colored bars to indicate the current status of the referenced object. The colors match the status colors configured on the Graphic tab in Site Settings.
8	Current value	Appears only when live values are shown. Lists the current value and units (if applicable) for the configured attribute. If the configured attribute is the referenced object’s Present Value or default attribute, the value appears as a link to open Commanding.
9	Current priority or configured attribute	When live values are shown and the configured attribute for the block is Present Value, this area lists the referenced object's current command priority when applicable, and is blank if Present Value does not support command priorities or its Priority Array is empty. For all other cases, this area lists the name of the configured attribute.

Figure 4. Logic Editor layout

Table 3. Logic Editor layout

Number	Name	Description
1	Logic Blocks pane	Select from a range of logic blocks to create or edit a logic diagram. Hover over a logic block to see the name of the logic block. See Which logic blocks are available and what do they do? for more details.
2	Logic canvas	The logic canvas provides the display area for the logic that is currently open. You add, move, and delete logic elements in this area to create your logic diagram.
3	Logic Checker	Check the logic you created to find out if there are any configuration warnings. Hover over the relevant block or exclamation points to learn more about the configuration warnings.
4	Paste	Paste elements that you cut or copied on the logic canvas. Keyboard shortcut to paste: Ctrl + V
5	Select	Select an element of the logic diagram on the logic canvas to move or edit it. When you select an element of the diagram, the horizontal toolbar opens. Use this panel to edit the values in the property panel, copy, cut, duplicate, or delete an item. Keyboard shortcut to select: V
6	Pan	See different views of the logic diagram. Keyboard shortcut to pan: H
7	Undo	Undo the previous action on the logic canvas. Keyboard shortcut: Ctrl + Z
8	Redo	Redo or reverse the previous undo action on the logic canvas. Keyboard shortcut: Ctrl + Y
9	Zoom In	Zoom in to the logic canvas. You can also move the wheel button on your mouse to zoom in.
10	Zoom Reset	Zoom Reset fits a logic diagram within the logic canvas. The zoom level is adjusted based on the content of the logic diagram.
11	Zoom Out	Zoom out of the logic canvas. You can also move the wheel button on your mouse to zoom out.
13	Save	Save the logic diagram.
14	Cancel	Cancel your work.

Which logic blocks are available and what do they do?

What is a Latch block?

The Latch block holds a binary value until you command it to reset. Latch blocks help capture rapidly changing binary states that might otherwise be missed. The input of the Latch block is a binary attribute, sampled every time the logic system runs, which is every five seconds.

Reset determines if the output of the block changes with a change in the value of the input. When Reset is True, the output of the Latch block stays its original value, even if the input changes value. Reset is also a binary attribute. To change the value of Reset, click Command on the input reference block in the Logic Viewer and issue an Inactive or Active command.

This table translates the value of the input or reset binary attribute into True and False values for the Latch block:

The following table and figure summarize the operation of the Latch block:

Figure 5. Latch block example

What is a Sequencer block?

Sequencer blocks activate devices in a sequential order based on the rank of the device and whether the device is enabled. Lower ranked devices are activated before higher ranked devices, and higher ranked devices are deactivated before lower ranked devices.

The input value at which the sequencer activates or deactivates each device is based on the make and break limits configured for the Sequencer. See Table 39 for information about configuring the make and break limits. The defaults for a 3-stage Sequencer with a range of 0–100 are the following:

Sequencer blocks can output a value for minimum of 2 and maximum of 8 devices. The following table describes the components of a Sequencer block:

What is a Span block?

The Span block applies a range and extrapolated values to an input to produce an output. This table describes the Span block components:

The Span block creates a linear relationship between the low input/output and high input/output pair. If the Input for the Span block falls between the low and high input, the Output of the Span block is found on the line between the low and high pairs.

The following example shows a graphical picture of how the Span block works:

Figure 6. Span block example 1

The line connecting the low and high pairs (blue line) represents the linear relationship between them. When you enter an Input for the Span block, the logic finds where the line crosses that input and provides the corresponding output. The output must lie on the thick blue line. Using the previous figure, if you enter 5 for the Span block Input, the block would find 5 on the Input axis and provide an output of 5.5 because that is where the line crosses an Input value of 5. The green line shows this relationship.

If the Span block is configured to clamp the value of the Output, the Output of the block is restricted to the range between (and including) the low and high Output you enter for the block. Range clamping is the default setting. For example, assume you are using the values in the following figure and have clamping set to True. If you enter an Input of 5, you still generate an Output of 5.5, because the original line crosses an Input of 5 at 5.5, which is between 4 and 8 (low and high output). If you enter an Input of 12, you generate an Output of 8, because where the original line crosses an Input of 12 is higher than the high output (see where thin blue and thin green lines intersect). If clamping is True for both high and low, the output must lie on the newly drawn thick blue line.

Figure 7. Span block example 2

The Span block works for the reverse span also, if the Output High is lower than the Output Low. See Table 42 for information about editing Span blocks.

What is a Rate Limit (RL) block?

The Rate Limit block controls the rate at which its Output changes with variations in its Input value. If rate limiting is disabled, this block passes the value of the Input to the Output. If rate limiting is enabled, this block limits changes to its Output to an increment determined by the Step Equation, executed according to the rate limit. This table describes the components of the Rate Limit block:

Rate Limit blocks use the Step Equation to determine the maximum increment (step) the Output can change to match the Input if the two differ. The Step Equation recalculates the step every time system logic executes (every 5 seconds).

The Step Equation looks like this:

Step = Rate Limit/60,000 x Actual Period, where Rate Limit is the rate per minute to increase or decrease the Output until it matches the Input, and where Actual Period is the time in milliseconds since the last execution of the block. The system logic and Step Equation execute every 5 seconds (5,000 milliseconds).

For example, if the Rate Limit block is set up like this:

Rate Limit = 10

Actual Period = 5,000 (milliseconds)

The Step Equation looks like this:

Step = 10/60,000 x 5,000

Step = 0.8

So, the maximum increment the Output can change on its way to match the Input is 0.8.

What is a Timer block?

This table describes the components of the Timer block:

The LCT contains five different types of timers, including the Pulse timer, On Delay timer, Off Delay timer, Minimum On timer, and Minimum Off timer. Each type uses a duration (how long the timer is active) and unique functions to generate an Output.

What is a Pulse timer?

The following table and figures illustrate the function of the Pulse timer.

Figure 8. Pulse timer example 1

Figure 9. Pulse timer example 2

What is an On Delay timer?

The following table and figures illustrate the function of the On Delay timer.

Figure 10. On Delay timer example 1

Figure 11. On Delay timer example 2

What is an Off Delay timer?

The following table and figures illustrate the function of the Off Delay timer.

Figure 12. Off Delay mode example 1

Figure 13. Off Delay mode example 2

What is a Minimum On timer?

The following table and figures illustrate the function of the Minimum On timer.