In order to perform the demonstration activities in εCEDAC an engineering prototype for the modelling of evolution control applications, the download to distributed embedded devices as well as the connection to a formal verification tool have been developed and prototypically implemented by the project partners. The prototype covers important project results in order to demonstrate the possibilities of the new εCEDAC technology. For the execution of evolution control applications a modified version of the µCrons (www.microns.org) middleware/runtime (MARTE) was used in all demonstration use-cases. The following figures shows the main elements of the developed prototype.

eCEDAC Engineering Prototype

The goal of the Bachmann demonstrator was to show the enhanced engineering capabilities of the εCEDAC method and the extended IEC 61499 system model for its application in motion control applications. Therefore a distributed control system as depicted in the following figure (consisting of a Bachmann PLC, a Bachmann Panel PC for visualisation and an engineering PC with an IEC 61499 environment) was setup. An Ethernet based communication was used for the data-exchange between the different devices. The PLC was responsible for the motion control task(s) of electrical motors. The visualisation and parameterisation of the motion control was carried out in the Panel PC. The engineering and configuration of the PLC and the Panel PC was done via the engineering PC equipped with the eCEDAC engineering prototype.

Motion Control Application

kirchner SOFT implemented two different demonstration uses-cases. In the first one the εCEDAC engineering prototype together with the adapted µCrons runtime environment was used to demonstrate the reconfiguration of encoding algorithms for communication over several embedded controllers. Therefore encoding/decoding algorithms which are used to encode or decode data that are communicated between controllers have been synchronously dynamically reconfigured.

In the second demonstrator use-case kirchner SOFT prototypically implemented the basis of the eCEDAC method in their own IEC 61131-3 compliant engineering tool logi.CAD and the corresponding runtime environment logi.RTS. The already existing feature instance reload in logi.CAD / logi.RTS provided the basis for the prototypical implementation. With the eCEDAC method it’s now possible to guide the reconfiguration process (through the RINIT, RECONF and RDINIT phases). The following figure shows parts of the modelling sequence for RECONF for the guided instance reload (exchange) of a P with a PIDT1 controller.

Evolution sequence with the IEC 61131-3 tool logi.CAD from kirchner SOFT

The goal of the SIEMENS VAI demonstrator was to present the bumbles reconfiguration of a 4^th order filter in the feedback term of a control loop for hydraulic cylinders in milling processes. The following figure shows the general setup of the demonstration use-case. To show the differences between the εCEDAC method and state-of-the-art approaches the exchange of the filter was done using the εCEDAC method and using the state-of-the-art method instance reload. The usage of the εCEDAC method showed that it is possible to exchange the filter without any disturbances whereas this is not the case with state-of-the-art approaches.

Bumbles exchange of a Butterworth with a Chebyshew filter in a control loop for hydraulic cylinders in milling processes

The goal of the LOYTEC demonstration use-case was to demonstrate the εCEDAC method for a distributed building automation system. Therefore LOYTEC implemented a gateway (GTW) for the integration of a LON building automation network into the εCEDAC approach. The following figure shows the demonstrator configuration. The temperature control in an office building executed by the εCEDAC method was chosen as demonstration use-case.

Distributed building automation control system

The goal of this demonstrator was to show the evolution capabilities of εCEDAC in a distributed control application. To show how such an evolution works an example has been created that uses two embedded control boards (DIGI ConnectME development boards called DIGI1 and DIGI2). Both embedded boards are equipped with the Net+OS 6.3 real-time operating system (which is based on the ThreadX open source project) and the IEC 61499 compliant runtime environment MARTE with enhanced reconfiguration services which was developed in the µCrons project. The initial control application performs the following steps:

• A HMI device (e.g. PC) sends a user input (a number) to the DIGI1 device over Ethernet.
• DIGI1 device sends data to DIGI2 device over Ethernet.
• The DIGI2 device sends the data to the HMI device over Ethernet and this device displays the result to the user.

All communications in this application is over Ethernet, but this can be changed online by an evolution control application. This application has been designed such that it changes from a communication over Ethernet to a communication over a serial link (the hardware layout is shown in the following figure).

Reconfiguration of communication links between two embedded controllers

Downtimeless reconfiguration of a control circuit: Several reconfiguration scenarios have been applied to a linear servo drive of a gantry system. On the one hand, a conceptual study has been applied to identify the possibilities and difficulties of the proposed εCEDAC evolution method. In detail, the velocity controller as well as the position controller of the cascaded control circuit have been changed during operation (see following figure). In detail, the velocity controller has been exchanged on the device. The position controller was shifted to another device within the network. The results of this study led to a more structured approach for the engineering of downtimeless system evolution.

Linear servo drive demonstrator (left), Exchange of the position controller – current velocity for correct (red)t and wrong (green) transition management (right)

The verification of system evolution was tested by a simple application, which counts up an integer value and sums it within an internal variable. After reaching a certain limit, the application stops. There have been to different reconfiguration scenarios applied utilizing the verification methodology developed in the εCEDAC project.

• Change of the threshold for stopping the application, and
• Exchange of the addition by a subtraction without loosing the current value of the internal variable.

For the rule-based checks within the verification method, a wizard has been developed. The following figure depicts two pages of this wizard. On the left side, the calculation of the initial system state is done. Therefore, the current system state is loaded from the devices and the evolution application (which will be downloaded for the verification process) is "virtually" added to this system state. On the right side, the checks within the RINIT sequence are given. Based on the analyses of the evolution application, the commands within the reconfiguration logic are checked according to the given rules.

Wizard for the rule-based verification: Calculation of the Initial System State (left), Calculation of the RINIT sequence (right)

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