Munich, Germany - The scalable multi-channel Eltec camera concept can process up to 32 cameras on one basic unit, and the Ethernet patch cables guarantee industry-compatible and low-cost cabling. Thus, the company supports complete solutions in association with this intelligent camera concept right up to the evaluation computer. It is, therefore, possible to cover numerous applications ranging from electronics manufacture, automation and process control, transportation and logistics, up to safety applications.
The multichannel cameras are build with standard components
If objects have to be investigated from different viewing angles, or very large image fields have to be observed, the bandwidth from the camera to the computer increases significantly. There is therefore a permanently increasing number of applications which require many cameras with large sensors connected to one computer. The objective of this development of an innovative camera concept was therefore a solution with intelligent, remote camera heads, an industry-compatible and cost-effective cable concept for digital image transmission, and a modular, scalable architecture. In addition, the camera system should make full use of the high bandwidth of state-of-the-art server chipsets, and also fit in a compact weatherproof housing.
CMOS sensor chips are preferably used in the cameras, since they provide a high reading rate together with high resolution at a relatively low price. Camera versions with a full-frame shutter were necessary so that there are no oval distortions as generally produced by a rolling shutter. CMOS sensors are appropriate for compact designs, but there are only a few with the desired shutter which "freezes" a complete frame when a pulse is generated.
The CMOS sensors used have a wide VGA resolution and a frame rate of 50 Hz (non-interlaced) together with a freeze-frame shutter for geometrically accurate recording of moving objects, and allow transmission per LVDS with up to 700 Mbit per channel. Applications with CCD sensors are also possible for special requirements, e.g. reduced noise. The camera heads with the sensors are small and light (for example, the CCD version measures just 47 mm x 40 mm x 40 mm), but a standard C-mount lens can be used nevertheless.
The data are already produced by the sensor in digital form so that the conversion to a serial LVDS format is relatively simple. If the transmission frequencies are selected appropriately, low-cost patch cables for Gigabit Ethernet can be used. These cables can have lengths between 20 cm and 15 meters, thus allowing flexible designs.
The cameras are controlled independent of the pixel interface via a noise-immune RS-485 connection. The pixel interface for the cameras and frame grabbers is completely implemented in FPGAs. Thus several cables can be provided flexibly in parallel. As a result of the error detection function implemented in the FPGAs, checking of the data consistency is simple to carry out.
The transmission format has been selected such that maximum transmission rates are achieved with reduced cabling costs. The low-cost patch cables of category CAT 5e which are used in large numbers for Gigabit Ethernet are suitable for the cabling. Electrical transmission of the image data is over an LVDS interface. The required computing performance is provided in the intelligent camera units by fast yet low-power ETX or COM Express CPU modules. These CPU modules offer the complete functionality of a PC on one card. Together with a corresponding graphics output, a full-scope operating system with GUI can be used.
The CPU modules are fitted on motherboards which support the project-specific I/Os. The advantages provided by the flexibility of an FPGA are again utilized here. A fieldbus interface is used for the control outputs, since ready-to-use interfaces are already available which handle the complex real-time communication and are easy to address via dual-port RAMs.
It is of course necessary for the computer to be able to process the data transmitted by the cameras. A standard PC with its three expansion slots rapidly reaches its limits. For cameras with a high image rate or when using several cameras the server technology with its high bandwidth as used provides significant advantages. Up to 32 cameras, which all transmit their data simultaneously, can then be connected to one system. In addition, network interfaces are also available for direct connection to Gigabit Ethernet.
The Eltec Toolkit is available for software support, and is available in Linux and Windows versions. Control of the cameras via RS-485 is supported by example routines in source code.