Erhard Lutz, Head of the Software Development Department at ROVEMA, about SERCOS III
"SERCOS III fits perfectly for packaging machines"
ROVEMA in Fernwald, Germany, belongs to the technologically leading manufacturers of packaging machines. World-wide more than 29,000 packaging machines from ROVEMA are delivered. Almost all leading brand manufacturers are among the international clients.
Erhard Lutz, Head of the Software Development Department, holds the key position in regard to the automation of the packaging machines. ROVEMA implemented SERCOS III as the first manufacturer of packaging machines. SERCOS III shows the most dynamic development among the Ethernet protocols with a market share of below 10% according to the study “Ethernet and Safety Ethernet 2010 to 2012”. For this reason Thomas Quest interviewed Erhard Lutz about his experiences with this Ethernet protocol.
What is the main advantage of SERCOS III for your applications?
We could realize unique selling propositions. Our know-how is focused on the motion core of packaging machines. We decided for a central control system. Our automation system „P@ck-Control“ operates the complete coordination of the axes including the position control. All software modules use a central data server.
As an unique selling proposition we developed a so-called dynamic limit-value calculation. If the operator modifies one parameter at the machine, all other machine parameters are automatically adapted to this change in real time. So the operator sees immediately on the HMI, which parameters in which ranges are still available, and which impact on the machine can be expected, e.g. output. Additionally all parameters and their ranges, being not any longer available, are hidden. In the result any incorrect entries by the operator are no longer possible, in fact, faulty operations are eliminated.
This is an unique selling proposition feature that could be strengthen in context with the implementation of SERCOS III.
Another point is that the number of axes will continue to increase at the packaging machines. In the near future we can expect about 30 to 35 axes at our packaging machines. At the time being we can synchronize 75 axes in 1 ms with SERCOS III. If it should become even more we will simply synchronize further 75 axes via a second ring.
The fact that faulty operations are eliminated is certainly a strong argument for the end-users. Are there further points why SERCOS III could be of interest from the end-users’ view?
First of all the end-user does not say, I prefer ProfiNet or SERCOS III or any other bus. What large end-users are demanding from time to time is the brand of the control system or the hardware. We use as standard a IPC-control developed by our own. Through the openness and standardization a universal drive and automation interface is available for ROVEMA ensuring among others the smooth integration of drives and devices from the most varying manufacturers. This opens up a high degree of flexibility to deal with the customer requests.
All the EMC problems in the past have almost disappeared with SERCOS III, they simply do not occur any more. Not to speak of lower wiring efforts and fewer hardware components leading to less susceptibility at packaging machines providing further advantages to customers.
Our tabular bag packaging machines offer a special seal-technique to the customer. While sealing the required force is not constant but rising according to an algorithm already applied for a patent. So higher packaging and product qualities are provided.
The product quality is also increased by the fact that the manufacturing of the seal-seam is monitored in such a way that parts of products in the seal-seam's range are identified in real time while producing causing immediately to defined actions. So scrap is reduced.
The sophisticated architecture and the high speed of SERCOS III enable us to realize fast algorithms via the control system, e.g. position control, speed and torque precontrols, status controls. The continuous measurement key perfectly integrated into SERCOS III permits us the realization of accurate pressure forming regulations and similar things. As far as I know this is not provided by other Ethernet protocols.
Finally the diagnostics. A modem or a VPN connection is included in each machine. By means of remote diagnostics we can look into the machine, each terminal, each motor. At the motor we can determine torque, heating of the motor, effective torque, peak torque and even the energy consumption. Of course that makes the troubleshooting at the end-user substantially easier.
How are you coping with project engineering and start-up with SERCOS III?
The start-up of the machines has become easier and faster with SERCOS III. I have already mentioned that the EMC problems disappeared. Furthermore all axes are integrated via SERCOS III. So at the start-up we can drive with reduced torque thus avoiding damage. SERCOS III is simply uncomplicated.
With the application engineering, i.e. the bus configuration, we initially had some problems because there were still no configuration tool. Finally we developed our own solution and now it is running smoothly.
With a view to the future, what should be modified or improved at SERCOS III?
Well, the diagnosis, the bus diagnosis, should become still simpler for us. Possibly we might again work together with our development partners. The peripherals to SERCOS III is another point concerned. Here I wished, besides the already varied supply, there would be available more devices with interface to SERCOS III such as frequency converters, sensors, printers, weighing modules, cameras or modules for format setting. As long as this peripherals are not completely offered on the market, adaptations are still necessary.
From our view SERCOS III fits perfectly for packaging machines. We are only using the standard parameters of SERCOS III, no proprietary parameters, because they are completely sufficient for packaging machines. These standard parameters are all openly available, can be downloaded on the Internet, this is standard to the third. And in opposition to other Ethernet bus systems there are no different versions of Sercos but one SERCOS III for all applications.