PSCAD™ V5.1.0 Black Box and Independent C Code

A Field Guide for Interconnection-Grade EMT Work

Electromagnetic transient (EMT) models have become the currency of modern interconnection. Every time an inverter-based resource, an HVDC link, a STATCOM, or a large electronic load is brought to a point of interconnection, the studies that decide whether it can connect—and under what conditions—increasingly hinge on EMT-domain analysis performed in PSCAD™/EMTDC™. That shift has created two practical problems that have very little to do with the physics of the model and everything to do with how the model is handled: how do you share a model without giving away the proprietary control logic inside it, and how do you take control logic you have validated in simulation and put it to work outside the simulator entirely?

PSCAD’s V5.1.0 release answers both questions directly. The Black Box feature lets you collapse an entire module hierarchy into a single, compiled, non-module component—preserving exact behavior while hiding the source. The Independent C Code feature (often called the C Coder) does the inverse for controls: it translates a control module into portable, standalone C that compiles outside PSCAD, including onto bare-metal hardware. At Keentel Engineering, we work with both sides of this exchange every week—receiving obfuscated vendor models on the study side, and helping clients package and port their own logic on the development side. This guide explains what each feature actually does, where the sharp edges are, and how we use them in interconnection-grade work.

Why this matters for interconnection

ISOs and transmission owners increasingly require validated EMT models for IBR and large-load studies, and OEMs are understandably unwilling to expose their control IP. Black Box is the mechanism that squares that circle—letting a developer hand over a model that runs identically without revealing the schematic underneath. Understanding exactly what an obfuscated model still exposes, and what it does not, is a core competency for anyone running or reviewing those studies.

Part 1 — The Black Box Feature: Obfuscation Without Compromise

The Black Box algorithm automates the complete conversion of a PSCAD page-module hierarchy into a user-defined component. It is not a cosmetic wrapper; it regenerates the model as compiled machine code and rebuilds the component around it. Three things happen under the hood, and it is worth understanding each because they determine what the recipient of a black-boxed model can and cannot see.

What the algorithm actually produces

1. Fortran source generation

Black Box emits Fortran source formatted specifically to run with EMTDC as an external file. This is the same fundamental code path EMTDC uses internally, but the algorithm formats it with the subroutine structure needed for multiple-instance compatibility—so the resulting component can be dropped into a schematic more than once without symbol collisions.

2. Automatic object or library file creation

Optionally, the generated source is compiled into an object file. If the module being black-boxed contains nested modules, every resulting object file is bound together into a single static library. This compiled artifact is where the real protection lives: once the logic is machine code in a .lib, the original source is no longer recoverable from the deliverable.

3. Automatic component creation

Finally, a component definition and instance are built from the contents of the hierarchy—automatically carrying over every port, parameter, graphic, and relevant script segment. The end result looks and connects like any native PSCAD component, but its internals are sealed.

Two restrictions you must plan around

Runtime objects are not supported. Switches, sliders, dials, and radio links cannot survive the Black Box operation, because they imply live user interaction that a compiled component cannot expose in the same way. Before you run the tool, you have to deal with them, and you have exactly two choices:

• Bake in a fixed value. Replace the dial or slider inside the module with a constant tag set to a preset value. This is clean and simple, but it permanently locks that value into the component—there is no real-time variability left once it is sealed.

• Preserve real-time control. Move the control or radio link out of the module entirely. If the object is buried deep in the hierarchy, you must promote its signal upward through every intermediate level using ports or parameters until it reaches the top. The control then lives outside the schematic and drives the finished Black Box component as an external input—retaining live adjustability.

Keentel practice note

Decide the bake-in-vs-promote question before you build the hierarchy, not after. Promoting a deeply nested radio link through five module levels late in a project is tedious and error-prone. If a parameter needs to remain operator-adjustable in the delivered model—a fault-ride-through enable, a control mode selector, a gain trim—design its signal path to the top level from the start.

Transmission lines and cables: new in V5.1.0, and worth understanding

V5.1.0 extended Black Box to systems that include transmission lines and cables—a meaningful addition, because line and cable models carry solved segment data that has to go somewhere. The algorithm embeds the solved transmission-segment information inside the automatically generated subsystem script. The tower and cable configurations themselves stay fully hidden, but a portion of the solved data remains visible, and exactly how much depends on the line model you chose.

This distinction matters for IP protection, so it is worth being concrete about what leaks through each model type:

The takeaway is straightforward: if hiding the transmission-segment design is a priority, the frequency-dependent phase model exposes far less usable information than Bergeron. We factor this into how we advise clients on model packaging when line topology is itself considered sensitive.

Inside the Options panel: the settings that actually change your model

When you generate a Black Box, an Options dialog appears. You can also set these preferences globally in PSCAD’s main application options, where they save to your user profile—worthwhile if you black-box frequently. Most settings are self-explanatory; the ones below are the ones that change behavior, results, or protection, and they are the ones we pay attention to.

Code Script Usage Compatibility

This ensures the component’s internal definition script is compatible with a target PSCAD version. The critical caveat: it affects only the definition script, not the generated Fortran source. If you build a Black Box in 5.1 using subroutines from the 5.1 master library, setting compatibility back to 4.5 will not make it run in 4.5—that older version simply lacks the newer EMTDC master-library models. Compatibility flags do not back-port capability.

Feed Forward Signal Storage

Leave this on Force Disabled unless you have a specific reason not to. Choosing Assume Current Project Setting inherits the project’s “Store Feed Forward Signals for Viewing” state; if that is enabled, every feed-forward signal is read from and written to storage on every time step inside the generated Fortran. That can hurt code efficiency and simulation speed. However, there is a real failure mode here: some custom models read and write storage improperly, and Force Disabled can change simulation results once the Black Box replaces the original module.

A quick diagnostic before you seal a module

Run the project once with “Store Feed Forward Signals for Viewing” enabled, then again disabled (or vice-versa). If the simulation results change between the two runs, the module is storage-sensitive—select Assume Current Project Setting before you Black Box, then re-run the tool. This five-minute check routinely prevents a black-boxed component from quietly behaving differently than the module it replaced.

Inner component definitions — a bottom-up algorithm

Black Box processes a hierarchy from the bottom up. Picture a top module Top containing A, B, and C; A contains D; C contains E and F; and E contains G. The algorithm walks upward like this:

1. Black-box G first; its instance inside E is replaced by the new component.
2. Move up to E and F; both are processed and replaced inside parent C.
3. Black-box D, replacing its instance inside A.
4. Black-box the intermediate modules A, B, and C, replacing each inside Top.
5. Finally, black-box Top itself.

The Inner Component Definitions option decides what happens to those intermediate definitions (A through G). Keep them all if you want to reuse the individual children later; otherwise set Do Not Retain and PSCAD deletes the intermediates once the top-level operation finishes, keeping your project tree clean.

Component instance, parameters, and electrical ports

• Component Instance Creation — choose Create New Instance to attach the finished component to your cursor for placement, or Generate Definition Only to build it quietly in the project tree for later manual placement.

• Parameters — Obtain from Source Module Instance copies every preset value from the original module onto the new component (so a module with 20 custom-set parameters transfers seamlessly and runs immediately). The alternative reverts each parameter to its original default.

• Fixed and Switched Electrical Port Names —  internal electrical nodes are exposed as fixed and switched ports. Ten fixed nodes, for example, create a ten-element fixed-port array (NBBF). You may rename these internal ports for clarity, or leave the defaults.

• Definition Labels — comma-separated labels that categorize the component on the Models ribbon tab and integrate with the V5.1 Library Viewer pane—useful for keeping a growing library of custom tools organized.

Global substitutions

If your hierarchy calls global substitutions, you choose how they are handled:

• Embed Values — bakes the current substitution values directly into the component as literals. Once sealed, they are permanently locked.

• Make Accessible as Parameters —  converts them into component parameters under a new “Global Substitutions” category in the component properties dialog, so you can keep adjusting them exactly as before.

Passive Elements Obfuscation — the heart of circuit protection

This setting is the one that most directly hides proprietary circuit design. Enabling Replace with Runtime Configurable Passive Branch tells PSCAD to use a master-library component model to secure your data: the algorithm strips the specific R, L, and C values out of each electrical branch and moves them into the Fortran file as literal values. Because that Fortran is then compiled into an object or library file, the true values are completely protected. In the final compiled data file, the real component values are replaced by dummy values. The recipient can still see that an RL branch exists in the graphic—but the actual values are hidden.

Transmission segment names, resources, and compilation

• Transmission Segment Names — replaces real line and cable names with generic placeholders such as Tline1 or Cable1 to further obscure proprietary topology. The base prefix is customizable (default: “Segment”).

• Resource Folders — if unspecified, generated files land in the active project folder and clutter it fast. Point this to a dedicated directory (for example a Blackbox folder under your local temp path) to keep generated output organized.

• Binary Files Compilation — generate source only, compile with your current default compiler, or generate objects for every installed compiler at once. Because object, library, and .o files are bound to the exact compiler that produced them, building for all installed compilers is smart practice if you switch compilers regularly.

• Append Resource Files — automatically attaches generated binaries and source to the project’s resources branch, so you can black-box a module, swap it into the schematic, and run immediately. Choose No Action to skip the automation.

• Clear Existing Resources — a maintenance utility that purges the resources branch before appending new files, preventing a pile-up of stale libraries if you black-box often.

• Naming Prefix — a strict requirement. The prefix is prepended to generated subroutines so they stay globally unique. Without it, two libraries that each define a subroutine named, say, “x” will trigger a multiple-source error and the Fortran compile will fail. A distinct prefix removes that risk entirely.

Walkthrough and verification: trust, then verify

Consider a simple RectifierAC page module containing a basic source and an RL load. Right-click, choose Generate Black Box, set a destination folder, and confirm. One best practice governs everything here:

Compile clean first

Black Box uses the exact same netlist compiler PSCAD uses to build a project. So compile the project normally and resolve every existing error before you black-box anything. Sealing a module that already has build errors only drags those errors into the generation process.

After the operation, the destination directory holds a new folder named for the original definition module. Inside is a Fortran source file with the Black Box name appended—structured like a standard EMTDC-generated file but formatted with the subroutines needed for multiple-instance use. The libs folder contains compiler-dependent output: with GFortran, for instance, an object file is produced and automatically bound into a static .lib, which PSCAD labels with the compiler name for later compatibility.

The finished component is where verification happens. Its graphic shows a three-element port array, matching the three fixed nodes in the original module. The underlying script generates the DSDYN and DSOUT calls into the compiled rectifier subroutine and places all branch and node numbers into storage. The original network’s nine branches each appear as a single line in the branch segment—and because passive-branch hiding was enabled, dummy values stand in for the real R, L, and C. With no transformers or model-data components present, those segments are simply empty. The component behaves exactly as the module did, while its design is sealed.

Part 2 — The Independent C Code Feature: Controls Beyond the Simulator

Where Black Box keeps a model inside PSCAD but hides it, the Independent C Code feature does the opposite—it takes a control module out of PSCAD entirely. It translates a PSCAD control module into valid, standalone C that compiles separately from PSCAD for any purpose, including running directly on a microcontroller. For teams that prototype control logic in simulation and then need it on real hardware—hardware-in-the-loop rigs, embedded controllers, digital twins—this closes the gap between the model and the device.

A concrete example

Take a small module with two inputs and one output that computes the running ramp-up over time of sin(input 1) × input 2, added to its previous value, with a parameter to reset the accumulated sum. In simulation, the inputs come from a function of time and slider values—a Reset Time slider sets when the sum resets, and a Gain slider sets the multiplier. Running the case shows the output responding to those inputs. The goal is to lift exactly this logic out of PSCAD and run it elsewhere.

Generating the code and choosing data types



Right-click the module and choose Generate → Independent C Code. A dialog lets you pick the data types the generated C will use—important because target hardware often supports only certain types. You configure three families:

The complex-number options exist because many C compilers do not support complex types at all (hence No Complex), some support the C99 standard, and others—the Microsoft Visual C compiler among them—implement complex values through a structure rather than a native type. Once the types are set, click OK to generate.

What gets generated, and where

The output lands in the case’s current temporary build directory, organized into three folders:

• Libs — contains pscadlib.h and pscadlib.c, holding source for all C-export-enabled PSCAD components, with every data-type version of each needed function. The source is provided so you can modify or strip out code you don’t need for a particular compiler.
• Headers — auto-generated header files for calling the module code—one per module compiled (including sub-modules), each named to match its module-definition source.
• Source — the C implementation for each module, again one file per module, named to match the definition.

Using the generated code

A typical integration—say, a Visual Studio 2022 program that reads input from standard-in and writes output to standard-out—follows a consistent pattern. Include every header and source file from the generated output in your project, then wire up the call:

1. Include the main header. Its name is the exported module-definition name with a .h extension.
   
   
2. Declare a void pointer, initialized to null, for application memory. Even though it is a pointer, memory is statically allocated by default—so the code runs on hardware that forbids dynamic allocation. The pointer is bound to the static storage structure the first time the code is called.
   
   
3. Use the module’s I/O structure. Imported from the module header, its name is the module-definition name followed by _main; it carries inputs in and outputs out.
   
   
4. Assign inputs, then call the run function. Its name is always the module-definition name followed by _run. It takes a pointer to the void application-memory pointer, an integer run-type, and a pointer to the I/O structure.
   
   
5. Read the output from the I/O structure, then loop. On the first call, a null memory pointer triggers allocation, value initialization, and the first time step.
   
   

The run-type integer takes one of three values:

When the end time is not known in advance—as in a console program that runs until it reads a “Q”—you typically use only 0 during the loop and a single 2 at shutdown to release resources cleanly. (Passing 1 instead would run one final time step on the current I/O before cleanup.) By default the generated algorithm runs in real time, querying the system clock on each call—worth remembering when you benchmark or when deterministic timing matters.

Static versus dynamic allocation

Static allocation is the safe default for constrained hardware, but some situations call for dynamic memory—most commonly when you need multiple instances of the generated code running at once, or when the target allows dynamic allocation but caps static allocation. A small, well-defined edit to the generated source switches modes:

1. In the run function, remove the statically allocated structure (named application_memory) declared just above it.
   
   
2. Replace the two uses of that application memory with a call to malloc, passing the size of the structure.
   
   
3. Add a call to free for the pstate variable in the two places where it is set to null, before it is nulled.
   
   

With those changes, the module runs on dynamic memory and multiple instances can coexist in one application. Document the edit—because it is a manual modification to generated code, it must be re-applied whenever the module is regenerated.

Limitations: know what will and won’t export



The C Coder supports a deliberately bounded set of components. Two conditions must hold: the component must have no electrical aspect (it must be purely controls-based), and the mathematics behind it must not be proprietary to PSCAD. Within those bounds:

The unsupported components are excluded either because their implementation is proprietary or because they need additional detail that cannot be expressed generically. To check any component yourself, open its definition, look at the Scripts section, drop down the current-segment box, and select C. If a C script section exists, the component is C-Coder-ready.

Extending the C Coder with custom components

If a module includes a custom component you need to export, you can make it C-Coder-compatible by giving it a C script section. Edit the component definition, open the Segment Manager, add and highlight the C section, then switch the current segment to C. The code you place there is written verbatim by the C Coder, so it must be valid C—semicolons and all—outside of directives and substitutions. It is auto-indented when written to the C files.

The C script section uses the same control directives as other script sections, plus a few specific to C export:

• Control flow & structure: if / else / elseif / case, and begin, endbegin, top, and bottom—which retain their meaning from the Fortran script sections.

• Function placement: dsdyn / enddsdyn force code into the DSDYN function; dsout / enddsout force it into the DSOUT function.

• Includes: header declares a C #include for a header file; include pulls in script-section code (with its own directives and substitutions) from an external source.

• local — defines a local variable. It works much like the Fortran version, except the variable must be accessed using dollar-sign ($) substitution.

• stash — defines a variable that persists across the program’s execution—the C-export equivalent of the storage arrays used in Fortran sections. Stashed variables are also accessed with $ substitution.



• struct & symbol — both local and stash accept a struct keyword plus a structure name (you define the structure in the included C code), and symbol defines your own substitution for use within the section.

Once the C script section is defined, regenerate the independent C code; you can inspect the result directly in the generated module .c file. The component is then a first-class citizen of the C Coder workflow.

How Keentel Applies These Features

These are not abstract capabilities for us. On the study side, we routinely receive black-boxed EMT models from equipment vendors and developers, and a real part of model-quality review is knowing precisely what an obfuscated model still reveals—line lengths, phase counts, the presence (but not the values) of passive branches—and what it has genuinely sealed. That knowledge shapes how we validate a model we did not build and how we communicate residual exposure to a client who is handing their IP to a third party.

On the development side, we help clients package their own intellectual property for distribution to ISOs, transmission owners, and study consultants without surrendering control design. And when validated control logic needs to leave the simulator—for hardware-in-the-loop testing, embedded deployment, or a digital twin running alongside the physical asset—the C Coder path lets that logic move from PSCAD to silicon with its behavior intact. Used together, Black Box and Independent C Code turn a PSCAD schematic into something you can protect, deliver, and deploy.

Talk to Keentel

Need to package an EMT model for interconnection submission, review an obfuscated vendor model, or port control logic to hardware?

 Keentel Engineering provides power-system studies, POI interconnection engineering, EMT modeling, and owner’s-engineer services across utility-scale renewables, BESS, and large-load projects. Reach us at keentel.com to discuss your model-delivery or controls-export workflow.

About Keentel Engineering & Disclaimers

Keentel Engineering is a power systems and grid-interconnection firm with offices in Tampa, Florida and Austin, Texas. Our services span power system studies (EHV/HV/MV), point-of-interconnection engineering, substation and transmission-line design, utility-scale renewables and BESS engineering, owner’s-engineer services, and NERC O&P compliance, with deep EMT-modeling capability across interconnection workflows.

Non-affiliation and trademark notice

This document is an independent technical commentary prepared by Keentel Engineering for educational purposes. Keentel Engineering is not affiliated with, authorized by, sponsored by, or endorsed by Manitoba Hydro International Ltd. PSCAD™ and EMTDC™ are trademarks of Manitoba Hydro International Ltd. All product names, features, and trademarks referenced herein are the property of their respective owners and are used for identification and descriptive purposes only.

Feature descriptions reflect PSCAD V5.1.0 as understood at the time of writing. Software behavior may change across versions; always confirm against the official PSCAD Application Help (including the “Black Boxing Modules” section) and the vendor’s current documentation. For software support, refer to the official PSCAD support channels. This material does not constitute professional engineering advice for any specific project; engagement of a licensed engineer is recommended for project-specific application.

Technical FAQ

Common questions we field on PSCAD V5.1.0 Black Box and Independent C Code, answered from a study-and-delivery perspective.

Black Box

Independent C Code (C Coder)