the single unified interface for all applications and all process IO resources
in the RTOS based DACHS-Product-line from STEINHOFF
The process image is the single unique IO interface for all applications to the IO resources of an external process. It consists of a shared memory segment splitted into an input and output section containing an un-interpreted bit stream of IO bits. That IO section is read and written using a pair of pointers.
The process image is completely independent to the different fieldbus controllers and other IO controllers ... that means also the applications are independent of the different fieldbuses and other IO resources.
The IO information in DACHS are provided by optimized specific fieldbus drivers or non-fieldbus drivers dealing with other IOs .. e.g. Multi-IO boards. That concept makes sure that every fieldbus will be handled regarding its specific requirements ... therefore no specific functionalities are lost in complete implementations.
The IO data are provided with a standard time resolution of one millisecond.
A higher time resolution is archived by PCI fieldbus controllers which are providing already a process image in its dual ported memory (1MB or more). After mapping of that DPM no driver actions and no DMA transfer are necessary to transfer the IO data to the process image !
and different I/Os