This contribution describes a possibility to build critical real-time applications using RT Linux 2.3 and LabVIEW 5.1 for Linux. Therefore a software interface has been added to LabVIEW, which gives control over real-time processes running on RT Linux. Unlike LabVIEW-RT, the real-time processes are programmed as linux kernel modules using “C” and do not need additional devices for hard real-time features,… instead they run on the industry's standard PC architecture. All known Linux DAQ-card drivers can be used for data acquisition and control of external devices, as far as they are able to run on RT Linux. The real-time programming examples being presented are written in “C” and “G” and refer to a low-cost and modular data acquisition and control system, which is connected to the PC's printer port. A real-time control system has been developed which manages a biophysical experiment, using a PC with a Pentium 133Mhz and 32MB ram. It covers: 1. control of stepper drives, valves and power heating using pulse-width-modulation, thereby achieving near analog operation with precise synchronisity; 2. multi channel data acquisition (digital and analog, rate 1Hz..10kHz, resolution 8..18 bits); 3. multiple simultaneously and independently running feedback control loops for position and temperature. 4. online graphical visualization of measured data and user interface to control of the experiment; 5. real-time scripting and macro language for easy programming of repetitive automation tasks; 6. graphically controlled post processing of the obtained data. Finally, this fully functional real-time DAQ and control system was build up using only a fraction of the usually needed expenses. The use of open standards and modularity make this solution highly flexible and easy to adopt to future applications.

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