Tuesday 8 December 2009

Embedded controller

Complete, all-in-one solution for automation solutions
CANopen master/slave configuration capability facilitates tight integration of pneumatics, electric drives and I/O functions
Obviates need for a master PLC in many small to medium sized automation systems

About CoDeSys
CoDeSys is an acronym for Controller Development System. Developed by the German software company 3S-Smart Software Solutions GmbH back in 1994, it is now the leading hardware-independent IEC 61131-3 programming system for automation controllers, and can be downloaded free of charge from the company’s website. The system offers a variety of programming languages, including two textual editors and three graphical editors, enabling programmers to use the tool of their choice. There are now over 250 hardware manufacturers producing automation devices with CoDeSys compatible interfaces. The system is supported by the CoDeSys Automation Alliance – a group of independent manufacturers formed specifically to provide users with compatible hardware components – which has grown to include 100 members.

Festo has launched a powerful CoDeSys embedded controller for use with its renowned CPX series of multifunctional control terminals. The new CPX-CEC module provides machine builders with a technically elegant means of overseeing all the units in a CPX terminal – regardless of whether they are for pneumatic or electric drives, or I/O functions – using a fast, easy-to-program controller. Suitable for single and multi-axis applications, it can operate autonomously or in conjunction with a host controller such as a master PLC, and can also be used as an intelligent slave in fieldbus-based systems, to provide localised signal pre-processing.

The CPX-CEC embedded controller is essentially a PLC in its own right, but with additional functionality. Based on a high performance 400 MHz low power consumption 32-bit processor, backed by 64 MB of memory, it features an Ethernet 10/100 Base-T interface for programming and host controller communications, and uses a backplane bus system to communicate with other modules in the CPX terminal. The controller has a cycle time of just 1 ms – making it one of the fastest on the market – and can be supplied configured as a fieldbus slave or as a CAN master for controlling other CANopen devices, such as electric drives. It supports all popular fieldbus protocols, including PROFIBUS, PROFINET, Ethernet/IP, DeviceNet, Modbus TCP, CANopen, CC-Link and EtherCAT.

Motion control programs can be created very quickly and easily on a standard PC, using any of the textual or graphical editors available in the CoDeSys hardware manufacturer-independent IEC 61131-3 programming system, and then downloaded to the CPX-CEC controller’s non-volatile memory. The controller is equipped with the latest V.2.3 version of the full CoDeSys RTS (runtime system). Program creation is further simplified by the fact that Festo supplies a comprehensive CoDeSys function library with the controller, which contains control routines for all of the company’s electric drives, as well as diagnostic and condition monitoring routines for its pneumatic drives.

Whereas most CoDeSys controllers are panel-mount or rack-mount designs, the CPX-CEC is a true embedded solution – all component parts are completely enclosed within the module, which carries an IP65/67 rating against dust and water ingress. The ability to deploy the CPX terminal and its constituent modules in the same environment as the machine itself – even on the machine if required – provides system designers with a very flexible solution for decentralised control.

Placing this level of networkable intelligence locally at the CPX terminal offers numerous advantages, including a significant reduction in system wiring, faster I/O capabilities and much more convenient monitoring, diagnostics and maintenance. The built-in Ethernet interface provides a very convenient means of handling remote maintenance and diagnostics via TCP/IP or OPC server technology. Simply by using Festo’s CPX Web Monitor software, for example, users can monitor static and dynamic statistical data from any of the constituent modules in the CPX terminal, over the internet. The CPX-CEC also features a service interface for a Festo CPX-MMI handheld terminal, and is equipped with front panel LEDs to indicate program status and to provide local diagnostic feedback.

Another major benefit to machine builders is that the control code developed for the CPX-CEC is reusable; this means that if, as is often the case, a customer orders several machines but with different host controllers or PLCs, the underlying CoDeSys routines remain the same – which reduces development time and costs, and helps accelerate machine delivery.

The CPX-CEC module can either be used as a front-end controller or signal pre-processor, under control of a host computer, or it can function completely autonomously, executing motion control sequences stored in its internal memory. For many applications, especially small to medium sized automation systems such as pick-and-place, palletising, loading/unloading and labelling machines, the CPX-CEC can completely obviate the need for a master PLC. When the module’s fieldbus interface is configured as a CANopen master it can accommodate up to 31 electric drive axes, while the CPX terminal itself can be equipped to handle up to 512 I/O functions.

Festo’s CPX multifunctional terminals provide machine builders with a very flexible, modular approach to control, condition monitoring and diagnostics. The terminals can form part of centralised, decentralised and hybrid control schemes, and individual constituent modules can be changed at will, enabling systems to be reconfigured or expanded without altering the wiring.

Festo produces a wide range of CPX-compatible modules, including intelligent analogue I/O modules for temperature sensing and signal detection, PNP and NPN digital input units, M12 and M8 connection blocks, and two types of position transducers for use with pneumatic actuators.

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