Epsilon LD software enables hardware configuration of the REGUL controller family (R600, R500, R400, and R200).


Epsilon LD is an integrated software package that provides all the tools required for configuration, programming and maintenance of all the REGUL controllers. Having one package only enables you to flexibly use the most appropriate controller series in your project without having to learn new tools and approaches. Epsilon LD supports development of applications in the following languages:

  • IEC 61131-3:
    • FBD (Functional Block Diagrams)
    • LD (Ladder Logic)
    • ST (Structured Text)
    • IL (Instruction List)
    • SFC (sequential function diagrams)
  • CFC (Continuous Function Chart)

Network Scanner – Find all your controllers in the network for IP configuration
A specially developed tool, Network Scanner, is included into Epsilon LD to find all the REGUL controllers in your network, no matter what their network configuration is. Then the same tool can be used to configure IP addresses and names of the controllers.

Abstraction – Simple to start with PLC development
Abstraction level in the Epsilon LD separates controller configuration from the programming part. This approach allows for a developer new to PLC programming or to the use of REGUL controllers, to have a faster start with the system.

Visual PLC Editor
It is highly supportive to visualize the configuration of the system and have a clear understanding which rack contains which modules and visibly identify the state of the racks. To perform it, the software shows each system configuration in the visual editor, with drag-and-drop adjustments.

Redundancy Configuration
As the redundancy is at the core of the REGUL controllers, it was important to have a convenient tool to set up and monitor redundancy state. The tool allows you to see the type of the redundancy used in the system in the Visual PLC Editor, as well as indicate controllers to be used as main and hot-standby, compare firmware and application used in each of them, and switch the control from one to another.

Programming – Wide choice of languages to your taste
The modular structure of the projects in the Epsilon LD software supports the use of different languages more suitable to different parts of the application. IEC 61131-3 are integrated into the software and the developers can choose the preferred language for them. Additionally, there is support for CFC (Continuous Function Chart) and ANSI C. Since the application could be split into modules running with a different speed, each of the modules can use its own language too.

Online Software Update
One of the most distinguished features is the support of the live software update on the redundant systems without stopping them from the operation. When performing an update, the control is switched to the second controller while in hot-standby. Then, the application update is uploaded to the first controller and the control is switched back to it. After successful pickup of the new application, it is synchronized to the standby controller.

Each project in the Epsilon LD is developed in its own profile and you can keep as many as needed. Separate profiles allow you to get the same environment as when the application was developed. Reducing the need to search and fix library dependencies.

Integrated Visualization
Oftentimes, the requirements for visualization are less than the use of SCADA system. In those cases, developers can create an interface directly from Epsilon LD and download it to the controllers. There is support for two types – one is Target Visualization, when it is displayed on an HMI (for example, R400 or third-party device) or on a monitor connected to the CPU module; the second is Web Visualization available in corresponding versions of the CPU modules. In case of Web Visualization, a web server runs in the module supporting remote connection and remote display of the state and control of PLC in the defined interface.

Integrated Debugger
Once the application is developed, use the debugger to go step-by-step through your application to ensure smooth and correct running.

Remote Diagnostics and Maintenance
Design of the controller to be used in the locations that are difficult to reach or the travel takes plenty of time puts a special accent on the possibility to remotely diagnose and update controller. This is reached by the integrated tools in the Epsilon LD software that support collection of the diagnostic information, analysis of the operation, and update where necessary. This includes configuration of the I/O modules, update of the application, firmware update.

Real-Time Operation
Before download to the controller, the application is compiled into a package for real-time operating system in the controller. Operation under it allows each REGUL controller to deliver stable and secure performance in the industrial environments.

Version changelog

Version 1.6.0

The minimum system requirements for Epsilon LD were changed to

New Functionality

New functionality in Epsilon LD:

  • Added OPC UA configurator

New functionality in the controller software:

  • Added an ability to perform service functions from the graphical interface
  • Added support for OPC UA protocol for PLCs based on ARM platform

Added support for the new I/O modules:

  • R500 DI 32 111
  • R500 AI 08 131
  • R500 CP 06 111
  • R600 DA 03 022


Changes in Epsilon LD:

  • Was changed the algorithm for calculating bus timeouts during automatic configuration
  • Some interface improvements
  • Was added to network scanner an ability to block modifications of the network settings
  • Optimized network scanner

Changes to the Regul bus driver:

    • The default interval for re-initializing modules was reduced to 3 seconds

Added a property that notifies the bus driver of the activity of the second set in the redundant controller

Changes of the drivers of the IEC 60870-5 protocol:

  • 104 Slave: The network port opens only when the application is running.
  • Slave: Added additional send ACTTERM after ACTCON in response to commands
  • Added the ability to transfer timestamps in UTC
  • Added support for custom types LREAL and ULINT
  • Optimized driver initialization
  • Auto-timestamping option was added to import/export

Correction in the ModBus Serial Slave driver: The range of user functions was changed.

Changes in the System software of the controller:

  • Automounting external USB drives is now optional
  • Runtime version updated to
  • Added restarting of the network driver when it detects a malfunction in the adapter
  • Starting network services on the controller has become optional
  • The structure of the controller logs directory has been changed
  • Changed the indication of backup states on the front panel
  • Some improvements in reporting NTP performance
  • By default, the time zone is set to UTC
  • PLC bus service, redundancy and external network processes were separated and isolated from each other
  • Extended set of the diagnostic messages
  • Added access to the full controller log from Epsilon LD
  • Network configuration of the controller was combined in a single network.cfg file


  • Corrections in the drivers of the IEC 60870-5 protocol:
    • 104: Fixed a bug that in some cases led to disconnection after changing the PLC system time
    • 104: Possible blocking of the driver when the communication line is broken
  • Fixed general request for custom types
  • Fixed compilation error after data import

Corrections in the ModBus driver:

  • Serial: Fixed a critical error that caused an exception when using the ASCII operating mode on the R200 series PLC
  • Master: Fixed possible blocking of functional block ModbusUserRequest FB

Corrections in the controller system software:

  • Fixed critical vulnerabilities in information security
  • Runtime: Fixed rounding of time to 1 ms in task statistics
  • An analysis of the hardware error flag was added in the backup subsystem when reconnecting
  • In the redundancy subsystem, the probability of short-term removal of output signals during the transition from the Leading to the Autonomous state is eliminated
  • Fixed a serial port failure that occurred when a USB device was disconnected
  • Fixed error accessing some diagnostic files of the controller via FTP
  • Fixed a bug leading to delays (up to 25 ms) in exchange with I/O modules at high network load
  • Fixed the operation of the visualization component Webbrowser
  • Fixed incorrect presentation of data on the NTP service
  • Improved stability of OPC UA server
  • Fixed a problem that caused GPS to be disabled on the R200 CU after updating to version
  • Fixed a bug in the backup subsystem, sometimes leading to the reset of retain variables on the slave CPU when updating the project

Corrections in input-output modules:

  • Fixed list of commands for modules DA 03 021 (electronic overspeed trip)