A P P L I C AT I O N S S Y S T E M S

Cart Track 4.0
Self-driven, electric e-Carts from Krups Fördersysteme optimize the assembly
and testing track in the battery pack production of a German car manufacturer;
Turck's robust IP67 PLCs provide the decentralized operation control of the individual conveyor modules

The e-Cart systemtakes the drive andthus also the maintenance away from theconveyor track, thus
maximizing its
availability

In many places, the production halls of automobile
manufacturers or tier-1 suppliers very much resemble
a clockwork mechanism. The operating steps of robots
and co-workers at the individual stations are closely
synchronized so that the treated object can then be
returned to the process flow. However, if one cog sticks,
particularly if this cog is the production conveyor
system, the entire plant gets out of step.
Maximum availability and flexibility are top of thelist of customer requirements. This puts conveyor
system manufacturers under pressure to innovate. They
are required here to provide maintenance-free andmore flexible conveyor systems that are simpler andfaster to integrate, which are less expensive andavailable faster than alternative solutions once all
direct and inidirect costs have been offset.
Krups, a company with its main plant in Dernbach
Rhineland-Pfalz, is one of the market leaders in assembly and test automation. The company specializes inautomation systems for the efficient linking of assembly and testing stations. The new e-Cart systemprovides actively powered, intelligent workpiececarriers, which are able to rotate, lift, clamp or tilt
workpieces.
Krups latest device is a highly available conveyor
system which is breaking (or making) new ground.
Philipp Krups, second generation head of the company,
explains the basic idea behind it: “In a conventionalroller conveyor system the drive is located in theconveyor track. This involves a lot of mechanical partsin the track, and also the associated amount of wear.
With permanently installed systems, maintenance istherefore always a problem. That's why we wanted toturn the system round and remove the maintenancefrom the track. We therefore developed a passive trackthat is completely maintenance free. The wholetechnology and electrical system is now located in thecarts, the so-called e-Carts. These electrically driven
carts have a self-diagnostic function and can bedischarged from operation if required for preventative
maintenance. This means that the downtimes are
reduced and the track remains operational. It also

Turck's TBEN-L-PLC controls the Krups conveyor system modules – communication to the periphery is via CAN andto the main controller via Profinet or Ethernet/IP

makes any later expansions to the conveyor line very
easy to implement. The e-Cart system furthermore
makes it possible to implement more flexible production processes with smaller batch sizes. It could evenbe said that it is an Industry 4.0 conveyor.”e-Cart revolutionizes materials handling fore-mobility
Krups has launched the new conveyor system under
the name “LOGO!MAT e-Cart”. And where if not in theautomobile industry should one of the first applicationsof this conveyor system be implemented? The automotive sector is after all the early adopter of industrial
automation. This is a home game for Krups since thecompany does around 95 percent of its sales in theautomobile industry. Some of the customers of thecompany based in the Westerwald are integrators that
supply complete systems for automobile manufacturers, or also the integrators of the automobile manufacturers themselves. A major German automobile
manufacturer will therefore be using an e-Cart systemin future in the battery production facility for electriccars.
Krups uses a modular concept in order not to haveto re-invent the wheel. The system consists of a few
standard modules: Rotate modules, shuttle modules,
stopper modules and indexers. These units are combined in a layout according to individual customer
requirements and connected to the onsite control
system of the plant. The conveyor system supplies thecustomer's production system with report data andenables the implementation of bidirectional communication interfaces.
Decentralized control for modular conveyor systems“Previously there was always a main controller, to which
all signals were routed. This partly involved point-topoint wiring, but increasingly more often also decentralized I/O units. The problem here was the program-“In the long term wedon't just want to be a
supplier of mechanicalsystems but a supplierof plug and play conveyor systems – smartsystems that control
themselves and only
need a higher-levelmaster controller”

ming. A plant programmer normally programs
everything in one sequencer. However, if any condition
at switchon or after an emergency startup is present
that is not represented in this sequencer, the users
must move units by hand in order to restore a known
situation,” explains Christian Mies, control developer atKrups. “A conveyor system has to be programmed

QUICK READ
With its e-Cart system Krups Fördersysteme is responding to the increasing
requirements of modern assembly and test automation in terms of safety, lowmaintenance and communication. A zero maintenance track and intelligent
self-driven carts, combined with decentralized system components withstandard controls ensure the possibility of flexible and safe assembly automation. This increases availability and allows flexible processes for small batch
sizes. The individual modules of the track are autonomously controlled by
Turck's TBEN-L-PLC. With the multiprotocol-enabled IP67 PLC, Krups can offer
standard and optimized control sequences for the individual components.
Customers can thus reduce the time required for wiring and commissioning
and expand the system easily.

A P P L I C AT I O N S S Y S T E M S

At the stoppers andother function modules the e-Cart systemcommunicates withthe carts via NFC

differently in order to eliminate the need for manualinterventions. Conditions and appropriate reactions
have to be defined that are suitable for all situations.”
If the modules are controlled in the central controller,
customers have to make some changes that interrupt
the overall process. If faults later occur, these comeback to Krups – even though the company was not
responsible for them. This experience taught Krups one
thing: Ideally, every module should be autonomously
controlled.
Autonomous control increases process safety
Today each module operates externally as a black box,
which simply communicates bidirectionally with thecentral controller in both directions via a bus connection. The module runs its program in order to perform
its particular task: Rotating, transferring, traffic monitoring and reporting of module status. Each module istherefore controlled – exactly according to the development – and perfectly implements all possible
sequences. A plant controller is installed at the level
above this and controls the overall flow. However, theactual positioning sequences and the monitoring ofconditions is taken over by each controller at themodule.
Krups then no longer has to intervene in the controlof the overall plant, neither does the plant operator
have to control the conveyor system modules. Only theBefore – after: Thecontroller built
in-house by Krups (left)worked well but, compared to Turck's TBEN-L
module (right), wasconsiderably larger andmore complicated toinstall and only workedin Profinet networks

communication between the general controller and themodules has to be implemented at base level. In-house,Krups calls these conveyor system modules which havetheir own intelligence smart modules. The company
therefore looked for autonomous controllers ten years
ago, which can be installed directly on the modules.
Self-built IP67 controller“At that time we already looked for compact controllers
with IP67 protection. However, there was nothing on
the market,” Christian Mies reports. Krups therefore
helped itself first of all: “We had our own controller built
on a board, fitted all M12 plug connectors and placed
everything in a housing. This housing had to beprovided with drill holes plus a pneumatic system and adisplay. These were very big units and relatively difficult
to manufacture. We had to have the boards built, thehousings assembled and everything wired up.
Although this was successful, it was a laborious task,”senior boss Peter Krups explained the journey towards
an in-house module controller.
Since Turck launched its TBEN-L-PLC block controller
on the market a few years ago, Krups has been able tosave the effort required for a self-build. The company is
now using the IP67 controller in many machine models– not only in the e-Cart system. The control system forevery conveyor system element was written in Codesys.
The communication to the drives or valve blocks andother components of the module is implemented via abus interface, while the communication to the main
controller is mostly implemented via Profinet. “We now
have the benefit: The modules can be deployed
immediately and without the need for any other field
programming device, i.e. replace, insert, data backup.
In the ideal situation: the customer just has to connect
the 7/8 inch plug connector for 24 volt and the Ethernet connector for the bus connection,” Mies explains
the benefits for the users. For an international company
like Krups even the range of protocols offered by thecompact controller pays for itself, according to IT
manager Mies: “We can serve the US market with

more@TURCK 1 | 201928 | 29

Ethernet/IP in exactly the same way as the Europeanand Asian market, where the protocols are mixed. We
are currently concentrating on Ethernet/IP and Profinet,
but Modbus TCP would also be possible in principle if
this is required by a customer. The great thing here isalso the fact that all the Codesys licenses are containedin the Turck device. The license is there and we can use
it, regardless of the fieldbus the customer uses. We caneven use them when we sometimes need a small main
controller because the master licenses are also available,” Mies describes the different scenarios in which
the TBEN-L-PLC can be deployed.
e-Cart system saves power in battery production
The specifications of the e-Cart conveyor system inbattery production already make it clear that themanufacturer means it with e-mobility. With 130

which can be set automatically to the required configuration as input or output. If other I/Os are required,
Krups can expand the number of signals required with
the BL compact I/O module via the CAN bus connection. The BL compact modules are likewise designedwith IP67 protection and are mounted directly at theunits.
IP67 saves wiring
Krups has recognized the work that can be saved with
the IP67 technology. “Just routing the 24V cables andsignals to the twelve controllers on the stoppers andlabeling would be very labor intensive. The price of theTBEN-L-PLC covers this easily,” IT manager ChristianMies expresses his appreciation.
The e-Cart system is not only energy-saving andfail-safe, it also enables more flexible processes as»Just routing the 24V cables and signals tothe twelve controllers on the stoppers andlabeling would be very labor intensive. The
price of the TBEN-L-PLC covers this easily.«
Christian Mies | Krups Fördersysteme GmbHself-driven carts on a kilometer of conveyor track, thestage of small series production has been left behind.
Krups fitted 70 turntables and around 140 stoppers
on the track. 10 stoppers use a TBEN-L-PLC jointly asa gateway to the customer's main controller. Thisconsiderably reduces the number of bus nodes
required for the customer.
To change direction, the carts are moved by transfer
units to parallel tracks or their direction is changed byturntables. Unlike most conventional systems it ispossible to communicate with the carts of the e-Cartsystem. NFC (near field communication) units areprovided at the stoppers in order to use the TBEN-L-PLC
as a gateway to implement communication between
the main controller and the carts. In this way, carts canbe removed depending on their state or the presenceof warning messages. Another benefit: When the carts
are waiting, they do not consume any power – unlike
the conventional roller conveyor systems in which thedrives normally continue running – even if no cartons
have to be moved.

outlined in Industry 4.0 model scenarios and also
already implemented. Through the communication
with the workpiece carriers greater product variancecan be achieved, as shown in another application
example: Likewise in the automobile industry, thee-Cart conveyor system transports the vehicle axlesof two models. There are, however, 140 different typesof axles that the carts can move through production.
The actively driven workpiece carriers enable different
production steps to be activated easily or left out. Wait
times are minimized and different speeds can beassigned to the carts at the stations.
The e-Cart system with smart control technology
in the field thus helps to ensure the smooth and highly
efficient execution of flexible production processes.
In view of all this, it becomes clear that the image ofproduction as a highly synchronized clockwork
mechanism comes from a different time. Even if
production 4.0 requires the meshing of one cog inanother, the clocks of production 4.0 have to beflexible like those in Salvador Dali paintings.

BL compact provides additional I/Os via CAN
The sensors and actuators of the modules are connected directly to the TBEN-L-PLC. The block controller
provides eight universal channels on four sockets,

Author | Frank Paluch is sales specialist at TurckCustomer | www.krups-online.de/en
Webcode | more11951e