Lightning speed transfer on the data highway

Pepperl+Fuchs: At present, the communication and control of automated logistic systems is achieved almost exclusively using fieldbus systems. Conversely, the integration of new Ethernet-based networks is often problematic due to the inadequate performance of the transmission media used. The latest generation of optical data couplers can overcome these challenges with ease. Devices from the Pepperl+Fuchs LS680-DA series are the first optical data couplers on the market that can achieve a full fast Ethernet bandwidth of 100 Mbit/s. In addition to standard TCP/IP, protocol-free data transmission allows the transfer of all standard industrial Ethernet dialects. The usual limitations of WLANs in high-rack storage facilities, for example, are now a thing of the past. In addition to use as a communication channel for control systems, the door is open to a wide range of other applications such as camera-assisted services that transfer video streams from IP cameras.

The use of fieldbuses in automatic high-bay warehouses is state-of-the-art. Automation components on rail-mounted vehicles, stock feeders, moving vehicles etc. are integrated directly into control hierarchies via the fieldbus. Optical data couplers are used as the standard method for communicating with these units. Previously used optical data couplers achieved maximum transfer rates of 3 Mbit/s. Although they fulfill current fieldbus requirements, they do not offer an adequate signal strength. PROFIBUS systems, for example, operate in applications with a data rate of 1.5 Mbit/s.

Enhanced performance with no side effects

For a long time, it appeared that technical limits had been reached. Although there has been a greater need for higher transfer rates over the past few years, providers have not actually developed any products that fulfill this need or offer a reasonable cost/performance ratio. The call for appropriate solutions intensified following the arrival of Ethernet in the world of automation technology. Owing to the situation, numerous users started trying out radio solutions as a replacement for optical data transmission. However, these trials have remained in their infancy due to the special circumstances of high-bay warehouses. Steel constructions are the main source of the problem due to their grid structure, which is unfavorable for the propagation of radio waves. In addition, the network coverage in a warehouse of this nature may vary considerably depending on the loading state. The limited number of channels and the use of channels for other communication purposes also significantly detracts from the attractiveness of this kind of solution. When controlling expensive, highly dynamic industrial systems that are critical to company operations, even a brief or temporary disconnection must be ruled out completely when such technology is used. So it is hardly surprising that there is a continuous demand for solutions without the disadvantages mentioned.

For the first time, the featured devices from the LS680-DA range offer a solution for optical data transfer that is not afflicted with any of the disadvantages listed. Optical data couplers from Pepperl+Fuchs operate with full fast Ethernet bandwidth at a transfer rate of 100 Mbit/s, which far exceeds the current 3 Mbit/s. This revolutionary leap in performance not only lays the foundation for satisfying unfulfilled user requirements that have had to be deferred due to slow transfer speeds, but also allows the development of completely new application possibilities.

Suitable for all Ethernet dialects

Additional measures for transferring TCP/IP data are not required due to the protocol-free principle of the LS680-DA. The same applies for industrial Ethernet, where it does not matter if you use it as a Profinet, Ethercat or Ethernet IP, for example. This approach has finally removed a bottleneck in the market and industrial Ethernet can be used consistently right the way up to the stock feeder. Users are in no way limited when selecting a suitable network. Your decision to choose a fieldbus or industrial Ethernet should be based entirely on the application requirements. No additional engineering expenses are incurred because the devices behave transparently in relation to the network.

The new devices are the result of consistent further development of the successful LS610/LS611 product family currently available on the market and have been perfectly tailored to the target application areas through use of the latest technology. Tried and tested features such as tool-free click-clamp technology, M12 plug connections and alignment using highly visible LEDs have been retained. One beneficial side effect of protocol-free transfers is that only one universal device variant is required and so an unnecessarily large range of variants is avoided in the ordering, stockkeeping and spare parts procurement processes. One type /F1 device and one type /F2 device are required to build a transfer link. The specified range limit is 180 m and the operating range is 150 m. An adequate signal strength is available at all times up to this distance. Needless to say, optical data couplers operate from a range of 0 mm and there is no reason to fear overranges or telegram losses.

From the plug-and-play connection to the automatic alignment aid

The LS680-DA is designed for genuine “plug-and-play” use, i.e. opening the devices is not a prerequisite for operation and parameter settings do not require modifying. This is also the reason why the devices can operate without any kind of operating elements. M12 connectors are available for the electrical connection. The operating voltage is supplied via a “conventional” A-coded M12 connector. A D-coded M12 plug is used to establish the Ethernet connection. At the same time, this connection technology reliably ensures that the IP65 degree of protection is maintained throughout the device.

The devices operate with red and infrared light from laser class 1M, which rules out damage to the human eye. Looking at the laser source through a magnifying lens is not permitted, however. On the front of the device, there is a special highly visible alignment LED that allows for quick and convenient alignment of the two corresponding devices. As soon as the receiver detects the transmitter light of the device opposite it, the flashing frequency of the alignment aid decreases. If the light goes out, this indicates that the devices are perfectly aligned and a sufficient signal strength is available. The devices also feature a bar graph display for fine adjustment that enables easy alignment to the best setting.

Using synergy effects

The system uses a large, sharp light spot with a diameter of 1.5 m at a sensing range of 100 m to effortlessly compensate for vehicle vibrations caused by uneven rails or load changes. This is most beneficial during system modernization. A convenient mounting bracket that allows the device to make mechanical adjustments across two axes is available as an accessory. A 90° deflection unit, which is particularly effective when used for vertical data transfers, operates in the same way.

In the application area mentioned, a corresponding solution is usually required in order to position stock feeders linked via a wireless connection. A combination of LS680-DA optical data couplers and distance measurement devices from the VDM100 series offered by the same manufacturer is recommended here. Valuable synergy effects are generated during the handling, installation, alignment and operation of both systems because not only are the accessories for both devices identical, but a standardized mounting and alignment concept has also been implemented. The two systems can be operated directly beside one another without any risk of mutual interference.

Visions for the future

The main application area for fast optical data couplers is Ethernet-based communication with stock feeders and similar vehicles. The LS680-DA is also ideal for the simple implementation of new types of solution. One urgent concern relating to today’s availability requirements for high-bay warehouses is the timely elimination of any malfunctions. This is not always easy on large systems because malfunctions can sometimes occur at great heights. In most cases, personnel must climb onto the stock feeder in order to make qualified assertions about the causes of faults and decisions on how to proceed. Suitable cameras such as those used in monitoring technology are available as an alternative for simpler solutions. However, a suitable transmission medium has not been available up to now. WLAN has been the only option for this application because video streams still require high bandwidths despite the availability of compression standards such as MPEG. Optical 100 Mbit data transfers represent a much more convenient solution for this type of application. IP cameras can also be connected directly to the optical data couplers, while the live stream is followed centrally from a control console or remotely from the system manufacturer, for example. Only a PC with installed web browser is required. If a camera with actuator components is used, the camera can be tilted from the browser or the image can be zoomed, for example. The number of camera systems operated in parallel is not restricted in terms of the data quantities transferred. The full 100 Mbit/s is available at all times irrespective of the distance and allows the smooth transfer of several streams in HD quality along the same route. On this basis, numerous other application scenarios are possible, including the documentation of the rack loading condition or other inspection processes.