Which programming languages and tools can be used with EtherCAT?
There is no single “EtherCAT programming language.” The right language depends on which layer you are building. A machine programmer working with ready-made I/O and drives may spend the whole project in IEC 61131-3. A MainDevice developer may work in C or C++. A SubDevice vendor usually deals with embedded C, the ESC interface and conformance testing. A test or supervisory application may use Python, C#, Java or Rust through a supported API. EtherCAT defines the communication system; the programming language, real-time runtime, protocol stack and network configurator are separate choices.[1]
One useful rule: if you are programming a PLC, you normally work with mapped process variables—not with raw EtherCAT frames. The engineering tool reads ESI files, builds the process-data map and configures the network; the EtherCAT runtime generates the cyclic communication. Raw frame handling becomes your concern when you are developing the MainDevice stack, a new SubDevice or specialist diagnostic software.
IEC 61131-3 is the natural starting point for machine control
For ordinary machine automation, Structured Text (ST), Ladder Diagram (LD), Function Block Diagram (FBD) and Sequential Function Chart (SFC) are common choices. Platforms such as TwinCAT 3 and CODESYS integrate the PLC application and EtherCAT engineering into the same project. Beckhoff states that TwinCAT 3 PLC supports the IEC 61131-3 language set, while CODESYS EtherCAT Master SL combines the configurator, protocol stack, runtime component and diagnostics with its IEC 61131-3 development system.[2][3]
That means an engineer can write the sequence of a packaging machine in ST or Ladder while the EtherCAT configuration maps a servo status word, digital input or analog value into PLC variables. The application does not normally contain a “send EtherCAT telegram” instruction on every cycle.
C and C++ dominate when you own the communication layer
If you are implementing the MainDevice yourself, writing an embedded controller or developing a new SubDevice, C/C++ become much more important. SOEM is a lightweight open-source C library for EtherCAT MainDevice development. The IgH EtherCAT Master provides a Linux-oriented application interface with real-time integration options. On the SubDevice side, Beckhoff/ETG's EtherCAT Slave Stack Code (SSC) is written in ANSI C, and SOES is another portable open-source C stack.[4][5]
The language alone does not create deterministic control. Network-driver behavior, scheduler, operating system, task period and the stack architecture all contribute to the real real-time performance. A very fast C function running on an unsuitable scheduler can still miss the required cycle.
Python, C#, Rust and Java are valid choices—but the architecture matters
High-level languages are increasingly practical when the selected stack exposes a supported API. A current example is acontis EC-Master, which advertises application APIs for C/C++, C#, Python and Rust. The time-critical EtherCAT core can remain in the native real-time component while the user application works through the API.[6]
Python is useful for test automation, commissioning helpers, data processing and supported control APIs. It should not be assumed that an ordinary desktop Python interpreter by itself guarantees a microsecond-level deterministic schedule. C# is common for .NET engineering, HMI and supervisory applications. Rust is viable where the selected SDK provides bindings. Java can connect to a native EtherCAT stack through JNI or another supported binding, but Java itself does not supply an EtherCAT stack.
This is why a toy JNI method named “connectToEtherCAT” is not meaningful evidence of a working EtherCAT application. Unless it names the real stack API, network interface, device configuration and process-data mapping, it only demonstrates a Java-to-native function call.
TwinCAT 3 is an engineering platform, not a language
TwinCAT 3 combines hardware configuration, EtherCAT engineering, PLC, motion and diagnostics in one environment. Beckhoff also supports real-time modules written in C/C++ and model-based workflows with MATLAB/Simulink alongside IEC 61131-3 code. The code executes in the TwinCAT real-time runtime rather than relying on the ordinary Windows task scheduler.[7]
That distinction matters: saying “we program EtherCAT in TwinCAT” usually means TwinCAT is configuring the network and running the control application. EtherCAT itself is not a TwinCAT-specific language or API.
CODESYS EtherCAT Master SL brings fieldbus engineering into the PLC project
CODESYS EtherCAT Master SL integrates the EtherCAT configurator, a portable stack, direct Ethernet-interface access and diagnostics into the CODESYS development system. For users who already structure their machine around CODESYS PLC applications, this gives one engineering environment for control logic and fieldbus configuration.[8]
The runtime still matters. Different target controllers can have different real-time behavior, Ethernet drivers, licenses and optional motion features even when the project is built with the same CODESYS engineering system.
SOEM, SOES and EtherLab are developer tools rather than drag-and-drop machine builders
SOEM is useful when you want a compact C MainDevice library and control over your own application architecture. SOES targets embedded SubDevice implementations. IgH EtherCAT Master / EtherLab is aimed at Linux systems and provides a common application interface, process-data domains and support for different real-time approaches. The current 1.6 documentation describes integration with Linux real-time extensions as well as operation without them.[9][10]
These tools assume you understand the EtherCAT State Machine, process image, PDO mapping, Distributed Clocks and error handling. They offer control and portability, but they are not a substitute for understanding how EtherCAT works.
SubDevice development has its own toolchain: SSC and CTT
Developing an EtherCAT sensor, drive or I/O module is a different job from programming a PLC. Beckhoff's EtherCAT Slave Stack Code (SSC) is ANSI C. Its tooling can generate stack source code, ESI device-description data and documentation tailored to the device. The stack covers functions such as the EtherCAT State Machine, mailbox protocols, process data and synchronization support.[11]
CTT (Conformance Test Tool) performs a different function: it tests protocol conformance. ETG's download record lists CTT 2.8.2 as the release published on 1 September 2026. It is used to check device behavior and ESI-related requirements against the EtherCAT specifications; it is not a code generator.[12]
Configuration tools solve the network-description problem
Tools such as EC-Engineer import ESI files, scan topology, configure PDOs and Distributed Clocks, and export an ENI (EtherCAT Network Information) file for the runtime. This is a different artifact from the PLC or C/C++ application. The ENI describes the EtherCAT network; your application describes what the machine should do.[13]
That distinction is central to device integration. The application may request a velocity or read a sensor value, while the configuration layer defines where that value lives in the process image and how the SubDevice is initialized.
MATLAB and Simulink fit model-based and test workflows
Model-based control teams can use MATLAB/Simulink in two common ways. TwinCAT can compile model-based modules into its real-time runtime, and Simulink Real-Time provides EtherCAT MainDevice blocks that initialize the network from an ENI file. MathWorks explicitly documents ENI generation through tools such as TwinCAT 3 or acontis EC-Engineer.[14]
This can be useful for controls research, rapid control prototyping, test benches and HIL-style systems. The Simulink sample time, EtherCAT cycle time and physical I/O response must still be treated as separate timing quantities.
Diagnostics may matter more than the language during commissioning
Wireshark can decode EtherCAT command, address, Working Counter and Distributed Clocks fields. Vendor engineering tools can add topology views, state information, link counters and process-data monitoring. When a machine fails to reach OP state or a WKC changes, these tools may tell you more than the source code alone. The separate EtherCAT troubleshooting guide covers that diagnostic workflow.[15]
A clean packet capture still does not prove that a drive parameter, scaling equation or machine-safety function is correct. Communication evidence and application evidence are different.
A practical selection table
| Task | Typical language | Example tool / stack | What to remember |
|---|---|---|---|
| Machine PLC logic | ST, LD, FBD, SFC | TwinCAT 3, CODESYS | The runtime normally handles frames; the PLC works with mapped process data. |
| Custom MainDevice | C/C++, or supported C#/Python/Rust APIs | SOEM, IgH, EC-Master | Real-time behavior depends on OS/runtime as well as language. |
| New SubDevice | Usually C | SSC, SOES, vendor stacks | ESC/PDI, ESI, PDOs and conformance are part of the job. |
| Model-based control | MATLAB/Simulink model | TwinCAT, Simulink Real-Time | Model sample time is not the same as physical I/O response. |
| Network configuration | No programming language required | TwinCAT XAE, CODESYS, EC-Engineer | ESI → PDO/DC/topology → project or ENI configuration. |
| Diagnostics / test | Scripts optional | Wireshark, CTT, vendor diagnostics | A packet trace is evidence, not the complete machine diagnosis. |
The shortest way to choose
If you already have a PLC and ready-made EtherCAT I/O or drives, start with the controller vendor's engineering environment and IEC 61131-3. If you are building a PC-based MainDevice, stack/API and real-time OS choices become central. If you are creating a new EtherCAT device, you need a SubDevice stack, ESC/PDI design, ESI and conformance workflow. For HMI, SCADA, analytics or test automation, higher-level languages may be entirely appropriate without being responsible for the hard-real-time cycle.
The better question is therefore not “what is the best language for EtherCAT?” but “which layer of the EtherCAT system am I implementing?” For the communication mechanism, continue with how EtherCAT works; for device roles see MainDevice/SubDevice communication; and for stack/tool cost questions see EtherCAT licensing and cost.
Related OtomasyonAVM guides
• What is EtherCAT?
• How does EtherCAT work?
• How do EtherCAT MainDevice and SubDevice devices communicate?
• Which devices and sensors can be integrated with EtherCAT?
• EtherCAT technical specifications
• EtherCAT real-time performance
• Detecting and resolving EtherCAT network errors
• EtherCAT security
• EtherCAT and industry standards
• Industrial communication
Technical references
[1] EtherCAT Technology Group — MainDevice implementation, standard Ethernet interface and SubDevice ESC architecture. Implementation
[2] Beckhoff — TwinCAT 3 PLC / IEC 61131-3 languages. TC1200 TwinCAT 3 PLC
[3] CODESYS — EtherCAT Master SL: configurator, protocol stack, runtime component and diagnostics integrated in the IEC 61131-3 environment. Product data sheet
[4] OpenEtherCATsociety — SOEM, Simple Open EtherCAT MainDevice library. SOEM repository
[5] Beckhoff / ETG — EtherCAT Slave Stack Code is ANSI C; SOES is an open-source C SubDevice stack. SSC / SOES
[6] acontis — EC-Master APIs for C/C++, C#, Python and Rust; supported IDE/OS options. EC-Master / Programming languages
[7] Beckhoff — TwinCAT engineering/runtime supports IEC 61131-3, C/C++, MATLAB and Simulink modules. TwinCAT
[8] CODESYS — EtherCAT Master SL integrated fieldbus engineering. CODESYS EtherCAT Master SL
[9] EtherLab / IgH — open-source EtherCAT MainDevice for Linux and its application interface. EtherLab / 1.6 manual
[10] OpenEtherCATsociety — SOES portable C SubDevice stack. SOES
[11] Beckhoff — ET9300 EtherCAT Slave Stack Code and SSC Tool functions. ET9300 SSC
[12] EtherCAT Technology Group — CTT V2.8.2 release (1 September 2026) and conformance-test resources. ETG Downloads / CTT Knowledge Base
[13] acontis — EC-Engineer configuration, diagnostics, ESI import and ENI export. EC-Engineer
[14] MathWorks — Simulink Real-Time EtherCAT Init block; ENI can be generated with TwinCAT 3 or EC-Engineer. EtherCAT Init
[15] Wireshark — EtherCAT datagram display fields including command, address, Working Counter and DC fields. EtherCAT display-filter reference