Sigma LD Software

Sigma LD software enables hardware configuration of the REDUL controller family (B600, B500, B400, and B200).


Sigma LD is an integrated software package that provides all the tools required for configuration, programming and maintenance of all the REDUL 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. Sigma 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 Sigma LD to find all the REDUL 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 Sigma LD separates controller configuration from the programming part. This approach allows for a developer new to PLC programming or to the use of REDUL 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 REDUL 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 Sigma 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 Sigma 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 Sigma 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, B400 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 Sigma 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 REDUL controller to deliver stable and secure performance in the industrial environments.


To download complete your copy of Sigma LD, please, send an e-mail to

Version changelog

Version 1.6.1

New functionality

New functionality in system software of PLC:

  • Added a file / directory synchronization scheduler with support for external storage device
  • Added the ability to turn off the display after a set time
  • Added SNMP protocol support
  • Added support for time synchronization via PTP protocol on B500 (x86) controllers

New functionality of the PLC bus driver:

  • Added command to reset network segment blocking for managed Redul B000 switches and B500 CP06111 bus expansion module
  • Added support for I / O modules:
    • B500 AI08052
    • B000 CP061X1
  • Added support for the CPU module:
    • B500 CU00031
    • B500 CU00071 R (RW)


Sigma LD changes:

  • Added connection point setting in OPC UA configurator
  • Added a system parameter editor on the “PLC Service” tab

Changes to the system software of PLC:

  • The version of the runtime has been updated to
  • Added the ability to stop the NTP service at startup in case of an unacceptable discrepancy with the time sources
  • Added the ability to disable anonymous access to the OPC UA server
  • Added the ability to override the quality and timestamp for OPC UA tags
  • Added the ability to save / load lines to / from the database more than 80 characters
  • Added the ability to set visualization parameters on the PLC B500 CU00071 R (RW)
  • Added information about nodes and type of action for GeneralModelChangeEventType OPC UA events
  • Added support for SD memory cards in controllers based on ARM architecture
  • Added check of the priority of the backup task
  • Added function for working with strings of arbitrary length in JSON format
  • The possibility of obtaining the visualization password from the configuration file of the PLC B500 CU00071 R (RW) is excluded
  • Added regeneration of SSL certificates when renaming a PLC
  • The function of redundancy of the central processor for controllers on the ARM platform has been implemented

Changes to the IEC 60870-5 protocol driver

  • Added the ability to set spare bits in the timestamp
  • Added logging of time synchronization events
  • Slave: Added the ability to process C_CS_NA_1 commands by application software
  • 104 Slave: When the “Use message queue accumulation” flag is turned off, messages are not buffered.

Change in ModBus driver:

  • Fixed limitation on the number of channels

Changes in the PLC bus driver:

  • Added support for individual configuration of the communication module from the side of the central processor module, as part of a controller operating under two central processor modules
  • Added the ability to transfer the cold junction temperature value to the BX00 AI0XX31 temperature measurement modules
  • Added support for voltage measurement in BX00 AI0XX31 modules

Bug fixes

Fixes in Sigma LD:

  • Fixed indication of CU module status in partial redundancy scheme
  • Fixed HART Master configuration error when compiling the project
  • Fixed a bug that led to a warning about the version mismatch of the connected device
  • Fixed the value of the available dynamic memory of the controller, which led to an error when loading the application into the controller

Fixes in the system software of PLC:

  • Restored the ability to change the system time of the PLC
  • Restored the ability to use triggers in the database
  • SysSockPing function restored
  • Possible out of bounds of the string in the JsonGetValueIntoString function has been eliminated
  • Fixed rendering crash when using some rendering styles
  • Fixed writing of lines containing special characters to the controller database
  • Fixed a very rare bug with the controller freezing at startup
  • Fixed a bug in the PLC on the ARM platform, which led to the disconnection of the connection with the IDE and OPC DA server with a long 100% CPU load
  • Fixed a bug in the procedure for starting a factory reset
  • Fixed error restoring RETAIN variables for a child application
  • Fixed a bug with access to variables by unaligned address, which in rare cases led to an exception on the ARM platform
  • Fixed error writing to external USB storage
  • Fixed error importing network configuration from network scanner
  • Fixed a bug when working with .csv files, the generated files were not available from the IDE and via FTP
  • Fixed a bug with creating a database when specifying a character encoding
  • Fixed a bug that caused an exception when converting UTF-8 strings containing invalid characters
  • Fixed work with SFP modules that do not support connection speed detection
  • Fixed a rare bug that led to double freeing of memory in OPC UA
  • Fixed a rare bug that caused the controller to freeze when turned on
  • Fixed wear alignment of NAND flash in controllers on the ARM platform
  • Fixed distortion of statistics of network interfaces
  • Fixed damage to Ethernet packets during communication via the CP02021 module
  • Fixed application of network packet filtering rules at controller start
  • Fixed a critical error that caused the failure of task execution scheduling when adjusting the system time
  • Fixed a bug in the PLC on the ARM platform that caused the loss of log messages when power was removed
  • The error of restoring PERSISTENT RETAIN variables while using them with RETAIN variables has been eliminated
  • The GetMode function of the backup subsystem returned an incorrect value “BOOTUP” when going offline

Fixes in driver IEC 60870-5-104:

  • Fixed response to BREAK command, DEACTCON is returned instead of ACTCON
  • Fixed leak of descriptors when the connection is broken

Fixes in the PLC bus driver:

  • Fixed a bug that led to an exception in projects using more than 17 of 16-channel or 34 of 8-channel analog modules in one crate
  • Fixed algorithm for diagnostics of PP and ST modules of B500 series controllers
  • Fixed a bug in the exchange of service messages, which sometimes led to malfunctions of CP modules with a large number of racks

Corrections in the redundancy subsystem:

  • Fixed incorrect operation of the synchronization function
  • Fixed a bug that caused a short-term reset of outputs on common modules when turning on the slave CU module on the first bus
  • Fixed the return value of the SYNCHRONIZE function
  • Fixed false diagnostics of communication break at high computational complexity in the backup task

Version 1.6.0

The minimum system requirements for Sigma LD were changed to

New Functionality

New functionality in Sigma 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:

  • B500 DI32111
  • B500 AI08131
  • B500 CP06111
  • B600 DA03022


Changes in Sigma 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 Redul 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 Sigma 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 B200 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 B200 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 DA03021 (electronic overspeed trip)