Axon AT61 — Complete Guide to IEC 61850 Simulation for Substation Commissioning

What Is Axon AT61?

Axon AT61 is a comprehensive IEC 61850 simulation and testing tool suite developed by Axon Group, designed specifically for engineers working with modern substation automation systems (SAS) built on the IEC 61850 standard. It enables the simulation, testing, and commissioning of IEDs (Intelligent Electronic Devices), protection relays, substation gateways, and SCADA systems that communicate using the IEC 61850 protocol family.

AT61 is the dedicated IEC 61850 complement to Axon Test 5 (which covers DNP3, IEC 60870-5-104, and Modbus) within Axon Group’s power automation software suite. While Axon Test handles traditional telecontrol protocols, AT61 is specifically engineered for the object-oriented, data-model-driven world of IEC 61850.

AT61 supports all major IEC 61850 communication services:

MMS (Manufacturing Messaging Specification) — client and server roles
GOOSE (Generic Object Oriented Substation Event) — publisher and subscriber roles
Sampled Values (SV/9-2LE) — specialized capture tool
IEC 61850 Edition 1 and Edition 2 — both versions supported simultaneously

Why IEC 61850 Testing Needs a Dedicated Tool

IEC 61850 is fundamentally different from traditional telecontrol protocols like DNP3 or IEC 60870-5-104. Rather than fixed register addresses and simple data point lists, IEC 61850 uses:

An object-oriented data model — a hierarchical structure of Logical Devices (LD), Logical Nodes (LN), Data Objects (DO), and Data Attributes (DA)
SCL (Substation Configuration Language) files — XML-based files (SCD, ICD, CID, SED, IID) that describe the complete configuration of IEDs and substations
Report Control Blocks (RCB) — the mechanism for IEDs to send spontaneous data reports to clients, both buffered and unbuffered
GOOSE messages — high-speed multicast messages for protection functions, operating at sub-millisecond speeds over Ethernet
Sampled Values — digitized current and voltage waveform data from process bus merging units

Testing this architecture requires tools that understand the IEC 61850 data model, can parse and validate SCL files, and can simulate both the IED side and the client/SCADA side of the communication — exactly what AT61 is built to do.

AT61 Tool Suite Components

AT61 is not a single application but a suite of specialized tools, each targeting a different aspect of IEC 61850 testing:

1. AT61 Client — MMS Client Simulator

The MMS Client tool simulates a SCADA system, engineering workstation (EWS), or gateway acting as an IEC 61850 client connecting to real or simulated IEDs:

Data model discovery:

Automatic discovery — connect to an IED and AT61 Client automatically reads and displays the complete data model hierarchy (LD → LN → DO → DA) from the IED itself
SCL file loading — alternatively, load an SCD or CID file to pre-populate the data model without needing the physical IED connected

Data reading and monitoring:

Browse and read any data attribute in the IED’s data model
Enable unbuffered reports (URCB) — subscribe to spontaneous changes in IED values
Enable buffered reports (BRCB) — subscribe to time-stamped change events with guaranteed delivery
Monitor data values with quality flags and timestamps in real time

Command execution:

Direct-Operate (DO) — single-step command execution
Select-Before-Operate (SBO) — two-step command with select confirmation, with and without enhanced security
Send commands to circuit breakers, disconnectors, and other controllable objects

Dynamic dataset management:

Create and manage dynamic datasets for flexible data subscription
Subscribe to existing datasets defined in the IED

Reporting:

Export data and test results to CSV format for documentation and analysis

Multi-connection:

Simultaneous connections to multiple IEDs — monitor a complete substation bay from a single AT61 Client instance

2. AT61 Server — MMS Server Simulator

The MMS Server tool simulates an IED at the MMS communication level, enabling testing of SCADA systems, gateways, and engineering tools that connect to IEDs as clients:

SCL-based IED cloning:

Load a real IED’s SCD or CID file — AT61 Server creates a functionally equivalent MMS server that mirrors the IED’s complete data model
The SCADA or gateway connecting to AT61 Server sees the same data model structure as it would see from the real IED

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Signal simulation:

Manual simulation — operator manually changes values of binary inputs (status), analog inputs (measurements), quality flags, and timestamps during testing
Automatic simulation — configure signals to change automatically at defined intervals or with random variation — simulates real field conditions without physical process stimulation
Configurable auto-simulation — individual or group configuration of auto-simulation behavior, including fixed interval or dynamic period simulation

Filtering and search:

Filter and search attributes to quickly locate specific signals within large data models — essential for IEDs with thousands of data points

Report generation:

Configure and enable report control blocks — test how client applications handle spontaneous buffered and unbuffered reports from the simulated IED

Multi-IED simulation:

Run multiple AT61 Server instances simultaneously — simulate an entire substation’s IED population from a single PC

3. AT61 GOOSE Tool — GOOSE Publisher and Subscriber

GOOSE (Generic Object Oriented Substation Event) is IEC 61850’s high-speed protection messaging mechanism, operating over Layer 2 Ethernet multicast with sub-millisecond timing. AT61 GOOSE provides both publisher and subscriber capabilities:

GOOSE Subscriber (Receiver):

Detect and capture all GOOSE message flows circulating on the Ethernet network
Display GOOSE message contents in decoded format — AppID, Dataset, sequence number, state number, time to live, and all data attribute values
SCL format display — show GOOSE content in SCL terminology for easy cross-reference with configuration files
Monitor multiple GOOSE publishers simultaneously
Verify correct GOOSE behavior after configuration changes or IED firmware updates

GOOSE Publisher:

Create GOOSE message flows from scratch — configure AppID, dataset, and data attribute values
Alternatively, create GOOSE flows based on an existing dataset from an SCD file
Generate manual or automatic changes in GOOSE data states — simulate protection trip signals, interlocking conditions, or breaker status changes
Test GOOSE subscriber behavior in protection relays and gateways without needing physical process conditions

Network-level operation: GOOSE operates at Layer 2 (MAC address multicast), not IP — AT61 GOOSE works at the raw Ethernet frame level, exactly as the standard requires.

4. Sampled Values Tool — IEC 61850-9-2LE Capture

A specialized application for Sampled Values (SV) — the IEC 61850 mechanism for transmitting digitized current and voltage waveform data from process bus Merging Units (MUs) to protection IEDs:

Capture and display:

Receive and decode IEC 61850-9-2LE (Light Edition) Sampled Values streams from connected Merging Units
Graphical waveform display — plot current and voltage waveforms in real time
Verify correct sample values, sample rates, and synchronization

Verification use cases:

Confirm correct operation of new Merging Unit installations
Verify waveform quality and scaling before connecting to protection IEDs
Diagnose Sampled Values communication issues during commissioning

5. Bay Simulator — Interactive Graphical Bay Emulation

The Bay Simulator is the most visually distinctive component of AT61 — a graphical tool for simulating a complete substation bay:

Graphical bay interface:

Visual representation of a typical bay: circuit breakers, disconnectors (isolators), earthing switches, current transformers (CT), voltage transformers (VT), and terminal blocks
Interactive graphical control — click on switchgear elements to change their state (open/close)

IEC 61850 MMS integration:

The Bay Simulator operates as a virtual relay — it communicates via IEC 61850 MMS, making it visible to SCADA clients and engineering tools as a real IED
Load a CID file to define the data model that the Bay Simulator presents to connected clients
Alternatively, the Bay Simulator comes with a built-in default data model for out-of-box use

Simulation modes:

Manual simulation — operator interacts with graphical controls to change breaker positions, generate alarms, simulate measurements
Automatic simulation — configure automatic state changes and measurement variations

Training applications: The Bay Simulator is explicitly designed for training — it allows technicians and engineers to learn IEC 61850 behavior and test their tools without needing physical IEDs or a real substation environment.

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Licensing note: The Bay Simulator is tied to an AT61 Server license — it is not separately licensable.

6. SCL Validation

AT61 includes SCL file validation tools:

Validate SCD, SSD, SED, ICD, and IID files against the official IEC 61850 schema definitions for Edition 1 and Edition 2
Identify configuration errors before attempting to commission physical IEDs
Detect incompatibilities between IED capabilities (ICD files) and the system configuration (SCD file)

IEC 61850 Edition 1 and Edition 2 Support

IEC 61850 has two major versions, and both remain in active use:

Edition 1 (published 2001–2004): The original standard, still installed in the majority of operational substations worldwide. Features the foundational MMS, GOOSE, and Sampled Values services.

Edition 2 (published 2009–2013): Significant improvements including better GOOSE subscriber declaration mechanisms, new data types and data objects, clarified buffered report behavior, and extension to applications beyond substations (wind, hydro, distributed energy resources).

AT61 supports both editions simultaneously — it can connect to and simulate Edition 1 IEDs alongside Edition 2 IEDs in the same test session, reflecting the real-world mixed environments found in substations during upgrades and expansions.

Practical Use Cases

FAT Testing of a New Protection Relay

An IED manufacturer delivers a new protection relay for factory acceptance testing. The commissioning engineer uses AT61 Client to connect to the relay, reads its complete data model, enables BRCB reports for protection pick-up and trip signals, and executes SBO commands to the trip output. All data is exported to CSV for the FAT report.

SCADA Integration Testing Without Physical IEDs

A SCADA integrator is developing the HMI for a new substation. The IEDs won’t arrive for 6 weeks. Using AT61 Server, they simulate all 8 protection IEDs in the substation — each loaded from its CID file. The SCADA connects to the simulated IEDs, HMI displays are verified, alarm handling is tested, and operator commands are confirmed — all without physical hardware.

GOOSE Protection Scheme Verification

A relay engineer needs to verify that a new GOOSE-based busbar protection scheme is configured correctly before energization. AT61 GOOSE subscriber captures all GOOSE flows on the substation network. The engineer verifies that each relay is publishing the correct signals in the correct GOOSE dataset, with correct AppIDs and MAC addresses. AT61 GOOSE publisher is then used to inject test GOOSE frames to verify that subscribing relays respond correctly to trip signals.

Merging Unit Commissioning

A new process bus installation uses IEC 61850-9-2LE Sampled Values from Merging Units. The AT61 Sampled Values tool captures and graphically displays the current and voltage waveforms from the Merging Unit, confirming correct scaling, sample rate, and synchronization before connecting the protection IEDs.

Training New Engineers on IEC 61850

Junior protection engineers need hands-on experience with IEC 61850 before their first substation commissioning assignment. The trainer uses the Bay Simulator — a graphical relay simulator that responds to MMS commands and generates GOOSE messages — to provide realistic training in a risk-free environment.

AT61 vs. Other IEC 61850 Testing Tools

Feature	Axon AT61	OMICRON IEDScout	SystemCorp IEC 61850 Explorer	Wireshark (free)
MMS Client	✅	✅	✅	❌ (decode only)
MMS Server simulation	✅	✅	Limited	❌
GOOSE Publisher/Subscriber	✅	✅	✅	❌ (decode only)
Sampled Values capture	✅	✅	Limited	❌
Bay Simulator (graphical)	✅	✅	❌	❌
SCL file validation	✅	✅	✅	❌
Edition 1 + 2 support	✅	✅	✅	❌
Dongle license (portable)	✅	✅	✅	N/A (free)
Independent client/server licensing	✅	✅	Limited	N/A
CSV export	✅	✅	✅	✅
Integration with Axon Exchange	✅ Native	❌	❌	❌
Integration with Axon Test	✅ Native	❌	❌	❌
Price tier	Mid	Premium	Mid	Free

AT61’s key position: Full-featured IEC 61850 simulation suite at a competitive price point relative to premium tools like OMICRON IEDScout, with native integration into the Axon Group ecosystem (Axon Exchange gateway, Axon Test protocol simulator). For teams already using Axon Test for DNP3/IEC 60870 testing, AT61 completes the IEC 61850 simulation capability within the same vendor framework.

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Licensing

AT61 uses a modular licensing model allowing independent purchase of components:

AT61 Client license:

Includes both the MMS Client and GOOSE Client (subscriber) tools
MMS client for connecting to real IEDs or AT61 Server instances

AT61 Server license:

Includes the MMS Server simulator
Also includes the Bay Simulator (Bay Simulator is tied to Server license)

Combined license:

Both Client and Server tools in a single license

Dongle license: Hardware USB key — portable between PCs, usable on any Windows computer with the dongle inserted. Essential for commissioning engineers working on multiple sites.

Software license: Bound to a specific PC hardware identifier.

A free trial version is available for evaluation.

System Requirements

Component	Requirement
OS	Windows 7, 8, 10, 11 (32 or 64-bit)
RAM	2 GB minimum, 4 GB recommended
Storage	500 MB for installation
Network	Ethernet adapter (Layer 2 access required for GOOSE)
Additional	WinPCap or NPCAP for GOOSE and Sampled Values (Layer 2 capture)

Important for GOOSE and Sampled Values: Since GOOSE and SV operate at Layer 2 (Ethernet frame level, not IP), the PC running AT61 must be directly connected to the substation LAN — not behind a Layer 3 router. WinPCap or NPCAP (packet capture driver) must be installed for Layer 2 access.

Frequently Asked Questions

What is the difference between AT61 and Axon Test? Axon Test 5 covers traditional telecontrol protocols: DNP3 (serial and Ethernet), IEC 60870-5-104, and Modbus. AT61 is dedicated exclusively to IEC 61850 — MMS, GOOSE, and Sampled Values. Both tools are from Axon Group and complement each other for complete substation testing coverage.

Can AT61 Server simulate multiple IEDs simultaneously? Yes. Multiple AT61 Server instances can run simultaneously on the same PC, each simulating a different IED (each loaded from a different CID file). This allows simulation of complete bay or substation IED populations for SCADA integration testing.

Does AT61 support IEC 61850 GOOSE interlocking testing? Yes. The AT61 GOOSE Publisher can generate GOOSE frames with any signal states, enabling testing of GOOSE-based interlocking schemes. Engineers can simulate breaker trip signals, busbar protection trips, and interlocking conditions to verify relay configuration without physical process excitation.

Can AT61 be used for IEC 61850 Edition 2 data model features? Yes. AT61 supports IEC 61850 Edition 2 features including new data types, improved GOOSE subscriber declaration, and Edition 2-specific Logical Node extensions. It can handle mixed Edition 1 and Edition 2 environments simultaneously.

Is the Bay Simulator a separate product? No. The Bay Simulator is included with the AT61 Server license and cannot be licensed independently.

Does AT61 support Sampled Values publishing (generating SV streams)? The current AT61 Sampled Values tool is described as a specialized capture/receiver tool. For SV publishing capability, check current AT61 release notes with Axon Group, as the product suite continues to evolve.

Summary

Axon AT61 is a complete IEC 61850 simulation and testing suite for substation automation engineers — covering MMS client/server simulation, GOOSE publisher/subscriber testing, Sampled Values capture, and graphical Bay Simulator for training and commissioning. Its support for both IEC 61850 Edition 1 and Edition 2, modular licensing, portable dongle option, and native integration with Axon Exchange and Axon Test make it a practical choice for protection engineers, system integrators, and utilities transitioning to or operating IEC 61850-based substations.

For licensing assistance or AT61 configuration support, contact our team via Telegram: t.me/DoCrackMe