JET real-time project test-bench software structure

Abstract A new test-bench for the JET real-time project was developed, being capable of generating analogue and digital stimulus signals to the control systems under test using previously stored JET pulse data. This platform allows systems to be more thoroughly tested in a wide range of scenarios before going on-line on the JET machine, reducing development and maintenance times and improving systems performance and reliability. This paper describes the real-time stimulus generator. Three layers of software which were developed to completely control 32 analogue output channels and 32 ATM virtual circuits as a real-time signal generator system: • Signal processing on Digital Signal Processor (DSP) software directly accesses the programmable control logic, issuing all the necessary commands using a 64-bit control register and 8-channel rate change registers. Real-time data flow from local SDRAM to digital to analogue converter (DAC) channel circular buffers is also controlled by the DSP. Interrupt service routines (ISRs) were developed to Control Software variables, as well as DMA data transfers. • Signal generation and operation as a Linux application controls the DSP in a client–server architecture. The most important functions of this software are: (i) access the JET database via MDSplus, (ii) data transfer to the local DSP SDRAM, (iii) issuing commands to the DSP state machine hardware controller, (iv) check DSP and hardware logic blocks status for errors and (v) the ATM link control. • Remote control operation using HTTP server running CGI scripts receives the remote configuration and commands from JET operations management software interface and passes it to the high level Linux software.