CODESYS Redundancy SL

An extension for CODESYS SoftPLC systems to realize redundant control systems.

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Product Description

CODESYS Redundancy SL makes it possible to run one and the same IEC 61131-3 application on two independent soft PLC systems at the same time. If a control fails, the passive control is activated. The function enables the mutual monitoring and synchronization of two controllers.

The redundant cross-connection between the two controllers is implemented using a TCP/UDP-based protocol. The active controller controls the I/O system, while the passive controller monitors the active controller and synchronizes itself with it. When the redundant system is started up, the first PLC started goes into the “standalone” state until the second PLC is started and synchronized. Then the first changes to the active state, the second to the passive state (standby). If a control fails, there is an automatic switchover.

A manual switchover can be initiated via a function interface. The boot application and the memory are updated automatically. IEC timers are synchronized in each task cycle.


Programming System

CODESYS Development System Version or higher

Runtime System

CODESYS Control V4.1.0.0 or higher

CODESYS Control V3.5.17.10 or higher

Supported platforms and devices

  • CODESYS SoftPLC systems


Note: Use the tool “Device Reader” to find out the supported features of your device (free of charge component of CODESYS Development System).

Additional Requirements

  • Two SoftPLC systems of the same type in the same version

  • TCP / IP stack


  • The synchronization is limited to one task.

  • IEC timers are locked during the execution of a task.

  • During the synchronization phase, the application data are copied between two cycles.

  • Pointers and other system resources must be stored locally on the respective device.


Single Device License: The license can be used on the target device/PLC on which the CODESYS Runtime System is installed.

Licenses are activated on a software-based license container (soft container), which is permanently connected to the controller. Alternatively the license can be stored on a CODESYS Key (USB-Dongle). By replugging the CODESYS Key, the license can be used on any other controller.

Note: In demo mode, the software runs for two hours without a license. After that, a manual restart is required.

Required Accessories

Optional: CODESYS Key


No Support

Technical support is not included with this product. To obtain technical support, please purchase a CODESYS Support Ticket.


For general error messages or pre-sales inquiries, please use the "My Question" contact form directly, which can also be used without logging in. A list of alternative support resources can be found in the support section of the CODESYS Group website.



A member of the CODESYS Group

Memminger Straße 151
D-87439 Kempten

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