During its operational lifetime of more than one decade, the Diagnostic Data Acquisition systems of the TEXTOR experiment experienced many modifications to comply with new requirements and the rapid development of software systems and computer components. Currently, again, the TEXTOR-94 data acquisition and handling systems are facing a major revision due to additional requirements imposed by the remote participation of Trilateral Euregio Cluster partners in the experimental programme of the fusion device. In order to open the system for new developments, but to retain the large investments in hardware instrumentation and software, a gliding upgrade of the current system to a revised one is aimed at, avoiding long shut down times of the system and loss of existing services. In this paper, we describe the recent developments and the design concept envisaged for the computer configuration, the data acquisition instrumentation and the networking.

The computer systems, previously consisting of VAX type machines for both data acquisition and data analysis tasks, have been resolved into an environment of distributed workstations specialized into control and data taking servers, data archive servers and user oriented data analysis stations. VAX computers have been replaced by DEC AXP Alpha machines to obtain an open system architecture, which provides a migration path into DecUnix and other operating systems based developments, while most of the existing OpenVMS based software investment can be preserved.

The data acquisition systems, up to now mainly based on CAMAC standards, face increasingly higher data volumes and processing demands. Therefore, the system is being extended to integrate VXI based solutions, which enable the application of more and modern commercially available equipment, i.e. containing pre-processing digital signal processors. While keeping the previous CAMAC serial highway concepts, the VXI integration is to be achieved by applying the KineticSystems VXI Highway Interconnect. This provides VXI coexistence with most of the available CAMAC equipment.

In a distributed and decentralized environment, the internetworking between the diagnostic systems plays an important and growing role. Therefore, the existing Ethernet has been partly replaced by FDDI links to increase throughput between the data generating and data analysis and archiving computer nodes. The Common Object Request Broker Architecture will be applied to solve the communication demands in a multiplatform environment.