Festo AX Controls (PLCnext) (Pro)

Note

This feature was added in realvirtual 6.3.3 (Professional) — Beta

Overview

The Festo AX Controls interface connects realvirtual directly to Festo AX Controls controllers running PLCnext Technology — the open IEC 61131-3 runtime platform developed by Phoenix Contact and adopted by Festo for their AX Controls series.

Communication uses Festo’s RSC (Remote Service Call) library over TCP port 41100, providing direct access to PLCnext Global Data Space (GDS) variables. The interface supports two data exchange modes: subscription mode, where the controller pushes variable updates at a configurable sample rate, and polling mode, where realvirtual reads all output variables each cycle.

Both Boolean, integer, float, and string variable types are supported. An editor button connects to the controller at design time to import variables and create realvirtual signal objects automatically.

Festo AX Controls (PLCnext) interface Inspector showing connection, subscription, and variable import settings

Prerequisites

1. realvirtual Professional — The Festo interface and RSC DLLs are included in the Professional package.
2. Network connectivity — Your development PC must be able to reach TCP port 41100 on the Festo controller.
3. PLCnext firmware — The controller must be running PLCnext firmware with RSC services enabled (standard on all AX Controls firmware releases).

Properties

Connection Settings

Property	Description
Host	IP address or hostname of the Festo PLCnext controller (default: 192.168.1.10)
Port	RSC service TCP port (default: 41100)
Use TLS	Enable TLS encryption for the RSC connection. Recommended for production deployments
Validate Certificate	Validate the server’s TLS certificate. Disable this for self-signed certificates in test environments
Username	PLCnext authentication username (default: admin)
Password	PLCnext authentication password (default: plcnext)
Connection Timeout Seconds	Timeout in seconds for connection and read/write operations (default: 10)

Subscription Settings

Property	Description
Use Subscription	Use PLCnext real-time subscription mode for output signals. When disabled, polling is used instead
Subscription Cycle Ms	Sample rate in milliseconds for subscription mode. Lower values give higher update rates. Minimum effective value is 10 ms (default: 100)

Variable Import

Property	Description
Import Root Path	Root component path on the PLCnext to browse for variables during signal import (default: Arp.Plc.Eclr for the IEC 61131-3 runtime). Leave empty to browse all components
Default Import Direction	Default signal direction assigned to imported variables (Input or Output)

Button:

• Import Signals from PLC — Connects to the controller from the Unity Editor, browses variables under the Import Root Path, and creates or updates realvirtual signal objects as children of the interface component.

Quick Start

1. Add the Festo AX Controls (PLCnext) component to a GameObject in your scene via Add Component > realvirtual > Interfaces > Festo AX Controls (PLCnext)
2. Add REALVIRTUAL_FESTO to Edit > Project Settings > Player > Scripting Define Symbols and recompile
3. Set Host to the IP address of your Festo controller
4. Enter your Username and Password
5. Configure Import Root Path to point to your PLC program (e.g. Arp.Plc.Eclr)
6. Click Import Signals from PLC — the interface connects, browses variables, and creates signal objects
7. Review the imported signals and set Input direction on any variables that Unity should write to the PLC
8. Press Play — the interface connects automatically and signal exchange starts

Signal Address Format

Each signal stores its PLCnext variable path in the Address metadata field. The path format follows the PLCnext GDS convention:

ComponentName/ProgramName.VariableName

Examples:

Signal	Address
Boolean motor status	Arp.Plc.Eclr/MainInstance.Motor1_Running
Integer counter	Arp.Plc.Eclr/MainInstance.PartCounter
Array element	Arp.Plc.Eclr/MainInstance.ConveyorSpeeds[0]
Array slice	Arp.Plc.Eclr/MainInstance.ConveyorSpeeds[0:9]
Struct field	Arp.Plc.Eclr/MainInstance.DriveState.ActualPosition

The component name for the standard IEC 61131-3 (Eclr) runtime is Arp.Plc.Eclr. Your program instance name is the name assigned to the program in the PLCnext Engineer project.

Communication Modes

Subscription Mode (default)

When Use Subscription is enabled, the interface registers all output signals with the PLCnext subscription service. The controller pushes updated values at the configured Subscription Cycle Ms rate. This is the recommended mode for real-time simulation as it minimizes latency and reduces network overhead.

If the PLCnext firmware does not support the subscription service, the interface automatically falls back to polling mode and logs a warning.

Polling Mode

When Use Subscription is disabled, the interface performs a batched read of all output signal addresses each communication cycle. This mode is compatible with all PLCnext firmware versions but has higher latency than subscription mode.

Input signals (Unity writing to the PLC) always use batched write operations regardless of which mode is selected. On the first cycle after connection, all input values are sent to initialize the PLC state.

Importing Signals from PLC

The Import Signals from PLC editor button provides one-click signal discovery:

1. The interface connects to the controller using the configured credentials
2. Variables are browsed from Import Root Path using the PLCnext variable browse service
3. For each discovered variable, a realvirtual signal object is created as a child of the interface component
4. The Address metadata field is set to the full PLCnext instance path
5. All imported signals receive the Default Import Direction — change individual signals to Input for variables that Unity should write back to the PLC

Supported PLCnext data types map to realvirtual signal types as follows:

PLCnext Types	realvirtual Signal Type
BOOL	Bool
INT, UINT, SINT, DINT, UDINT, BYTE, WORD, DWORD	Int
REAL, LREAL	Float
STRING, WSTRING	Text

Variables with unsupported types are skipped and a warning is logged to the Unity console.

See Also

• Interfaces Overview — All available interfaces
• Signal Manager — Managing PLC signals
• Custom Interfaces — How to build your own interface
• Compiler Defines — Adding scripting define symbols
• Keba Interface (Pro) — Similar RSC-based controller interface
• TwinCAT (Pro) — Another IEC 61131-3 based interface

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