Modifying SIMIT Component Type Editor (CTE) FLOWNET Components and Scaling Warnings

When modifying or creating custom FLOWNET hydrodynamic components (such as DrumWS) in the SIMIT Component Type Editor (CTE), an exclamation mark warning indicating 'Connections are outside the component at minimum width' prevents the component from appearing in the 'User Components' library catalog. In SIMIT V8.1/V9.x, this validation fault occurs because connection terminals extend beyond the configured symbol bounding box while horizontal or vertical scaling is active. To resolve the issue, open the basic symbol in CTE, uncheck 'Horizontally scalable' and 'Vertically scalable', or increase the minimum symbol width and height until all fluid connectors reside strictly within the graphic boundary.

SIMIT CTE Component Architecture and Geometry Rules

The SIMIT Component Type Editor (CTE) allows simulation engineers to build custom behavioral components or extend standard library modules from the FLOWNET hydrodynamic and thermodynamic libraries (e.g., pipes, boilers, steam drums). A SIMIT component consists of three architectural layers:

Mathematical Behavior: Differential and algebraic equations executed cyclically (Cyclic Calculation).
Connectors: Input, output, and physical topological terminals (e.g., FLN2 fluid net connections).
Visual Basic Symbol: The graphical representation, connection pins, and scaling rules displayed on the simulation canvas.

Root Cause of Symbol Boundary Warnings in FLOWNET

The CTE compiler enforces strict topological rules regarding terminal pin coordinates:

Symbol AttributeConfiguration StateOperational ImpactScalable FlagsHorizontally scalable or Vertically scalable enabledSIMIT allows dynamic symbol resizing on the canvas; connection pins must remain inside minimum bounds.Pin CoordinatesTerminal located outside Minimum Width / Minimum HeightValidation Error: Yellow exclamation mark; component blocked from 'User Components' catalog.Fixed DimensionScalable flags disabled, fixed dimensions assignedBounding box is static; connection pins lock to fixed coordinates; validation error clears completely.

Remediation Procedure in CTE Symbol Editor

To resolve the symbol dimension warning and successfully export the component to the user catalog:

Step 1: Open Component in Component Type Editor

In SIMIT, launch the Component Type Editor (CTE).
Open the modified FLOWNET component (e.g., DrumWS).

Step 2: Adjust Basic Symbol Scaling Properties

In the left navigation pane under the component structure, expand Visualization -> double-click Basic Symbol.
In the properties panel, inspect the Dimensions section:
- Option A (Fixed Symbol - Recommended): Uncheck the checkboxes for both Horizontally scalable and Vertically scalable.
- Option B (Maintain Scalability): Increase the numeric values for Minimum width and Minimum height until all fluid connector pins are enclosed within the bounding box.
Confirm that the yellow exclamation mark and error message 'Connections are outside the component at minimum width' disappear.

Step 3: Save and Refresh Catalog

Save the component in CTE (File -> Save).
Return to the main SIMIT simulation environment.
In the Task Card Components, click Refresh: the modified component now appears under User Components.

Verification

To verify that the custom component functions cleanly within SIMIT:

In the SIMIT project tree, open a simulation diagram.
Drag and drop the modified component from User Components onto the canvas.
Verify that the component places without graphical distortion and that all FLN2 fluid terminals display correctly.
Connect the drum terminals to adjacent FLOWNET pipes or valves: verify topological snapping occurs cleanly.
Start SIMIT Simulation (Simulation -> Start): confirm that cyclic calculations execute without syntax errors or matrix singularities.

Limitations and Operational Precautions

Operational boundaries when editing CTE components:

Syntax Compilation Errors: CTE provides basic text checking, but complex mathematical runtime errors (e.g., division by zero or square root of negative numbers) only manifest during simulation startup.
Library Migration: When upgrading SIMIT versions (e.g., V8.1 to V9.1 or V10), verify that custom CTE component schemas remain compatible with updated FLOWNET calculation kernels.
Preserve Standard Libraries: Never overwrite original Siemens library components in the installation directory; always save modified versions into project-specific user component folders.

Engineer FAQ

Why does CTE block components with connection pins outside the minimum bounding box?

If a component is scaled down to its minimum width on a simulation diagram, connection pins outside the bounding box cause broken topological links and visual overlap with neighboring blocks.

Is there a real-time syntax checker for CTE Cyclic Calculation code?

CTE performs lexical checking during save; however, full structural and equation validation occurs when SIMIT builds and compiles the simulation runtime model.