LJU Busmastersystems currently in use have been available since 2001 and have been implemented in a wider variety of Railbus and Inductive bus installations, proving reliable not only in the traditional fields of operation in Automotive production but also in numerous logistics installations in Germany and abroad. In these non automotive applications the dynamics of demand and track variability of the carriers are regarded as being considerably higher. This reliability is achieved because of consistent decentralization of control responsibility down to the carrier level, that LJU developed and implemented.

In summer 2015 LJU applied the first components of the new iDM-System successfully in a customers installation. This new iDM development combines the practical features of the actual railbus system with Ethercat network technologies. This advancement in technology will permit future integration of safety communication and other customer demands.

Merging components, will in most configurations, create not only a more powerful functionality but will provide greater cost efficiencies for customers to benefit from. LJU's new -iDM-System represents the core technology within Series 7 and the innovation found in the new generation of Series 8 controllers.
Improvements correspond to increased customer demands of:

  • Centralised operability
  • Comprehensive diagnostics
  • Safety applications
  • Cost efficiency.
A configuration-oriented system combines the LJU practical experience of the hundreds of historic installed base of Railbus and Inductive bus systems, coupled with the features of latest network communication. Integration of planning and startup tools and the variable scalable parameter structure of the whole installation ensures it is possible to increase the efficiency and reduce time in performing installation planning and startup, as well as later installation modifications. A Soft-PLC can be integrated into the MCU for smaller installations as well as enabling several PLCs can be connected for large installations.
See below an overview of main components of the LJU-iDM-System:
iDM-System MCU-Master Control Unit      NEW!

The Master Control Unit (MCU) is the interface between all track segments and the system controller. It is independently responsible for the management of trolleys in the connected system component. Its functions include the re-registration of trolleys across track segments (tracks) and the maintenance of safe distances between trolleys, among others. Its extensive functionality allows systems to be commissioned without a superordinate SPS, among other things. This makes an autonomous controller without SPS possible for small systems.

The MCU is based on the CX product series of modular top-hat-rail industrial strength PCs from the company Beckhoff. Its central unit is the CPU module CX2030 with an Intel®-Core™ i7 dual core CPU operating at a clock frequency of 1.5 GHz. The controller does not have a fan or other rotating components. Ethernet and EtherCAT® modules of the CX product series are used for the interfaces. To configure it as an iDM unit, the iDM MCU CC (Master Control Unit Control Center) is installed as a system component.

iDM-System TCU-Track Control Unit      NEW!

The iDM-Track Control Unit is an intelligent modem that allows bidirectional data transfer between the Master Control Unit and the trolley controllers. One TCU each transfers MCU data or data from the superordinate system controller to/from a track section (track). EtherCAT® is used for data transfers to/from the MCU, with the TCU configured as a certified EtherCAT® slave. A sliding contact bus or inductive bus is used for data transfers to/from trolley controllers.

Unit functions:

– Management of a maximum of 30/45 trolleys over a maximum distance of 200m (depending on data volumes per trolley)
– Monitoring data consistency in trolley controllers
– Diagnosis/display in order to display parameter tables, trolley status, communication status and quality
– Synchronization of time of day with MCU (uniform factory time)
- Synchronized operational/error logs

iDM-System Manager      NEW!

The LJU System Manager provides a very powerful configuration tool to the user. The installation configuration can be directly imported from dxf-format. Simulation tools allow plausibility checks and selective online control of carriers during system startup, what is extremely useful when the master PLC software is not ready yet.  Editing of features and values can mostly happen intuitively, otherwise there is a comprehensive documentation available. 

Online screen monitoring is a standard tool, also recording of communication protocols to easily debug problems with higher level data structures.

LJU Busmaster System (actual)

If a bus system is used, the data is transmitted to the trolleys in the system over the rail bus, for example over slide-contact rails or contact-free over inductive data bus (option). Commands, messages and trolley data are transmitted cyclically and acyclically over two bus lines A and B or over the inductive data bus between the trolleys and the system controller. To use one of these bus systems it is required to use an LJU Bus master system as an interface between the system controller (PLC) and the trolley controllers Optionally the PLC can be connected via the Profibus DP-V1, Profinet, Modbus+, Devicenet, Modbus IP or other systems available in the market.

All other tasks are independently handled by the trolley controller in conjunction with the bus master. The trolley drives through the system at the speeds specified by the system table (system map in the bus master) and parameterized in the controller. The controller uses the positions read by the PLA 14 (optical scanner for LJU position reading system) to detect the position of the trolley in the system and sends it continuously to the bus master. The bus master evaluates the position of all trolleys and indicates the free travel to each trolley.

Now if the trolley approaches another trolley, it automatically reduces its speed and drives to a parameterized distance. Positioning points can also be configured using the system table. If the trolley reaches these defined points, the trolleys precisely position to these points. Moreover in specified areas of the system the hoisting motors should automatically move up to certain hoisting heights. If the trolley reaches one of these areas, the hoisting motor moves up to the defined height as specified in the hoisting tables stored in the trolley and the bus master. The flexible configuration of tables allows the user to design ergonomically optimized workstations, thus the hoisting height can be set based on the workstation and person. This hoisting height setting can always be by operating interfaces, programs or product-related requirements.
Example of Application of Bus System:
  • Drive at multiple speeds
  • Automatic distance control
  • Automatic positioning
  • Automatic driving up to a hoisting height
  • Routing through internal routing table

Advantages of Bus Systems:

  • Positioning within millimeters with the implementation of the absolute-coded rails and PLA-14
  • Automatic distance control without additional sensors
  • Quick data transfer
  • Greater flexibility in functionality with increased number of commands
  • Detailed data transfer from the trolley to the system controller (e.g. for display purposes)
  • Configuration of trolleys via the system controller
  • Automatic update (e.g. of hoisting tables) in the trolley controllers
  • Automatic routing function (option)

Further information can be found in our download area.

Do you require consultation on a project if so please contact your nearest LJU partner (see partners on our contact page) or use our contact form.