Add new node-type FMU

CMakeLists.txt

@@ -91,6 +91,7 @@ find_package(Criterion)
 find_package(OpalOrchestra)
 find_package(LibXml2)
 find_package(OpalAsyncApi)
+find_package(FMI)
 
 # Check for tools
 find_program(PROTOBUFC_COMPILER NAMES protoc-c)
@@ -199,6 +200,7 @@ cmake_dependent_option(WITH_NODE_ETHERCAT       "Build with ethercat node-type"
 cmake_dependent_option(WITH_NODE_EXAMPLE        "Build with example node-type"                          "${WITH_DEFAULTS}" "" OFF)
 cmake_dependent_option(WITH_NODE_EXEC           "Build with exec node-type"                             "${WITH_DEFAULTS}" "" OFF)
 cmake_dependent_option(WITH_NODE_FILE           "Build with file node-type"                             "${WITH_DEFAULTS}" "" OFF)
+cmake_dependent_option(WITH_NODE_FMU            "Build with fmu node-type"                              "${WITH_DEFAULTS}" "FMI_FOUND" OFF)
 cmake_dependent_option(WITH_NODE_FPGA           "Build with fpga node-type"                             "${WITH_DEFAULTS}" "WITH_FPGA" OFF)
 cmake_dependent_option(WITH_NODE_IEC60870       "Build with iec60870 node-types"                        "${WITH_DEFAULTS}" "LIB60870_FOUND; NOT WITHOUT_GPL" OFF)
 cmake_dependent_option(WITH_NODE_IEC61850       "Build with iec61850 node-types"                        "${WITH_DEFAULTS}" "LIBIEC61850_FOUND; NOT WITHOUT_GPL" OFF)
@@ -309,6 +311,7 @@ add_feature_info(NODE_ETHERCAT          WITH_NODE_ETHERCAT          "Build with
 add_feature_info(NODE_EXAMPLE           WITH_NODE_EXAMPLE           "Build with example node-type")
 add_feature_info(NODE_EXEC              WITH_NODE_EXEC              "Build with exec node-type")
 add_feature_info(NODE_FILE              WITH_NODE_FILE              "Build with file node-type")
+add_feature_info(NODE_FMU               WITH_NODE_FMU               "Build with fmu node-type")
 add_feature_info(NODE_FPGA              WITH_NODE_FPGA              "Build with fpga node-type")
 add_feature_info(NODE_IEC60870          WITH_NODE_IEC60870          "Build with iec60870 node-types")
 add_feature_info(NODE_IEC61850          WITH_NODE_IEC61850          "Build with iec61850 node-types")

cmake/FindFMI.cmake

@@ -0,0 +1,26 @@
+# CMakeLists.txt.
+#
+# Author: Ritesh Karki <ritesh.karki@rwth-aachen.de>
+# SPDX-FileCopyrightText: 2014-2026 Institute for Automation of Complex Power Systems, RWTH Aachen University
+# SPDX-License-Identifier: Apache-2.0
+
+find_path(FMI_INCLUDE_DIR
+    NAMES fmilib.h
+)
+
+find_library(FMI_LIBRARY fmilib
+  PATHS /usr/local/lib /usr/local/lib64
+)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(FMI DEFAULT_MSG FMI_LIBRARY FMI_INCLUDE_DIR)
+
+mark_as_advanced(FMI_INCLUDE_DIR FMI_LIBRARY)
+
+if(FMI_FOUND)
+    add_library(FMI SHARED IMPORTED)
+    set_target_properties(FMI PROPERTIES
+        IMPORTED_LOCATION "${FMI_LIBRARY}"
+        INTERFACE_INCLUDE_DIRECTORIES "${FMI_INCLUDE_DIR}"
+    )
+endif()

doc/openapi/components/schemas/config/node_obj.yaml

@@ -27,6 +27,7 @@ discriminator:
     example: nodes/_example.yaml
     exec: nodes/_exec.yaml
     file: nodes/_file.yaml
+    fmu: nodes/_fmu.yaml
     fpga: nodes/_fpga.yaml
     iec60870-5-104: nodes/_iec60870-5-104.yaml
     iec61850-8-1: nodes/_iec61850-8-1.yaml

doc/openapi/components/schemas/config/nodes/_fmu.yaml

@@ -0,0 +1,7 @@
+# yaml-language-server: $schema=http://json-schema.org/draft-07/schema
+# SPDX-FileCopyrightText: 2014-2026 Institute for Automation of Complex Power Systems, RWTH Aachen University
+# SPDX-License-Identifier: Apache-2.0
+---
+allOf:
+- $ref: ../node_obj.yaml
+- $ref: file.yaml

doc/openapi/components/schemas/config/nodes/fmu.yaml

@@ -0,0 +1,71 @@
+# yaml-language-server: $schema=http://json-schema.org/draft-07/schema
+# SPDX-FileCopyrightText: 2014-2026 Institute for Automation of Complex Power Systems, RWTH Aachen University
+# SPDX-License-Identifier: Apache-2.0
+---
+allOf:
+- type: object
+  properties:
+    fmu_path:
+      format: uri
+      description: |
+        Specifies the URI to a FMU model
+
+    fmu_unpack_path:
+      format: uri
+      description: |
+        Specifies the URI to a directory which has the unpacked files of the FMU model (mainly the shared library and the modelDescription.xml for the model).
+
+    fmuWritefirst:
+      type: boolean
+      description: |
+        Specifies whether the model has to be writtem with input values before running. `true` denotes that the model should use the input values. `false` would make the model use default values instead.
+
+    startTime:
+      type: number
+      description: |
+        Specifies the start time for the simulation. Value has to be at least one `stepSize` lesser than `stopTime`.
+
+    stopTime:
+      type: number
+      description: |
+        Specifies the stop time for the simulation. The number of steps is calculated then by the difference between `startTime` and `stopTime` divided by the `stepSize`.
+
+    stepSize:
+      type: number
+      description: |
+        Specifies the stepSize for the simulation. Special care has to be taken to ensure that the value is equal to the value mantioned in modelDescription.xml.
+
+    in:
+      type: object
+      properties:
+        signals:
+          type: array
+          description: |
+            The input signals for the model have to be mentioned here as elements of an array while specifying the name (should be the same as that found in the modelDescription file) and the datatype.
+
+            **Example**:
+
+            ```
+            signals = (
+                {name = "In1", type = "float"},
+                {name = "In2", type = "int"}
+            )
+            ```
+    out:
+      type: object
+      properties:
+        signals:
+          type: array
+          description: |
+            The output signals for the model have to be mentioned here as elements of an array while specifying the name (should be the same as that found in the modelDescription file) and the datatype.
+
+            **Example**:
+
+            ```
+            signals = (
+                {name = "Out1", type = "float"}
+            )
+            ```
+
+- $ref: ../node_signals.yaml
+- $ref: ../node.yaml

etc/examples/nodes/fmu.conf

@@ -0,0 +1,58 @@
+# SPDX-FileCopyrightText: 2014-2026 Institute for Automation of Complex Power Systems, RWTH Aachen University
+# SPDX-License-Identifier: Apache-2.0
+
+nodes = {
+    file_output = {
+        type = "file"
+        # format = "csv"
+        uri = "/workspaces/node/fmu_temp/output.dat"
+    },
+
+    signal_node = {
+        type = "signal.v2"
+        rate = 100.0
+        realtime = true
+
+        limit = 100
+
+        in = {
+            signals = (
+                { name = "sine1",   signal = "sine",   amplitude = 1, frequency = 100   },
+                # { name = "in2",   signal = "constant", amplitude = 1  },
+            )
+        }
+    },
+    fmu_node = {
+        type = "fmu"
+        # Path to FMU file (.fmu)
+        fmu_path = "/workspaces/node/fmu_temp/asine.fmu"
+        fmu_unpack_path = "/workspaces/node/fmu_temp/fmu_asine"
+        fmu_write_first = true
+        stop_Time = 10.0
+        startTime = 0.0
+        stepSize = 0.2
+
+        in = {
+            signals = (
+                { name = "in1", type = "float" }
+            )
+        }
+
+        out = {
+            signals = (
+                { name = "out1", type = "float" },
+            )
+        }
+    }
+}
+
+paths = (
+    {
+        in = "signal_node",
+        out = "fmu_node"
+    },
+    {
+        in = "fmu_node",
+        out = "file_output"
+    },
+)

include/villas/nodes/fmu.hpp

@@ -0,0 +1,77 @@
+/* Node type: Functional Mock-up Unit.
+ *
+ * Author: Ritesh Karki <ritesh.karki@rwth-aachen.de>, Jitpanu Maneeratpongsuk <jitpanu.maneeratpongsuk@rwth-aachen.de>
+ * SPDX-FileCopyrightText: 2026 Institute for Automation of Complex Power Systems, RWTH Aachen University
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#pragma once
+
+#include <ctime>
+#include <string>
+#include <vector>
+
+#include <fmilib.h>
+
+#include <villas/format.hpp>
+#include <villas/node.hpp>
+
+namespace villas {
+namespace node {
+
+// Forward declarations
+struct Sample;
+
+class FmuNode : public Node {
+protected:
+  int parse(json_t *json) override;
+
+  int _read(struct Sample *smps[], unsigned cnt) override;
+  int _write(struct Sample *smps[], unsigned cnt) override;
+
+  bool writing_turn = true;
+  const char *path;
+  const char *unpack_path;
+
+  std::timespec ts;
+  pthread_mutex_t mutex;
+  pthread_cond_t cv;
+
+  fmi3_import_t *fmu;
+  jm_callbacks callbacks;
+  fmi_import_context_t *context;
+
+public:
+  FmuNode(const uuid_t &id = {}, const std::string &name = "");
+  struct fmu_signal {
+    unsigned int ref = 0;
+    fmi3_base_type_enu_t type = fmi3_base_type_enu_t::fmi3_base_type_float64;
+    std::string name;
+  };
+
+  std::vector<fmu_signal> signalIn;
+  std::vector<fmu_signal> signalOut;
+
+  int prepare() override;
+
+  int check() override;
+
+  int start() override;
+
+  int stop() override;
+
+  // ~FmuNode();
+
+private:
+  void parse_signal(json_t *json, bool in);
+  double currentTime = 0;
+  double stepSize = 0.1;
+  double stopTime = 0;
+  double startTime = 0;
+  bool stopTimeDef = false;
+  double nextTime = 0.0;
+  void get_vr(const char *var_name, fmi3_value_reference_t &ref,
+              fmi3_base_type_enu_t &type);
+};
+
+} // namespace node
+} // namespace villas

include/villas/nodes/opendss.hpp

@@ -33,7 +33,7 @@ class OpenDSS : public Node {
         mode; // Mode is set according to the function mode in OpenDSS
   };
 
-  bool writingTurn;
+  bool writing_turn;
   const char *path;
   timespec ts;
 

lib/nodes/CMakeLists.txt

@@ -202,6 +202,12 @@ if(WITH_NODE_WEBRTC)
     list(APPEND LIBRARIES LibDataChannel::LibDataChannel)
 endif()
 
+# Enable FMU node-type support
+if(WITH_NODE_FMU)
+    list(APPEND NODE_SRC fmu.cpp)
+    list(APPEND LIBRARIES FMI)
+endif()
+
 add_library(nodes STATIC ${NODE_SRC})
 target_include_directories(nodes PUBLIC ${INCLUDE_DIRS})
 target_link_libraries(nodes PUBLIC ${LIBRARIES})