Method to check module chaining in a modular software architecture located in an electronic unit with microprocessor comprising, apart from the microprocessor, a memory space (14, 16, 18), the method comprising: a)- during an inter-module call instruction belonging to the microprocessor's instruction set, said inter-module call instruction triggering execution of a save routine in privilege mode allowing writing to a protected memory which is accessible in read-only mode only except for the save routine, b)- from within the execution of the save routine executing in privilege mode, before branching the execution of the calling module to a precise point in the program of the called module: c)- saving automatically, in the protected memory, with the inter-module call instruction, an identification information used to identify the calling module to programs not executing in privilege mode, said identification information of the calling module consists in the content of one or more registers of the central processing unit in the microprocessor, d)- identifying an identification and program chaining check routine specific to the called module among several identification and program chaining routines, e)- checking whether the calling module is authorised to access the called module, if the calling module is authorised, branching to a specified point of the given called module. a)- during an inter-module call instruction belonging to the microprocessor's instruction set, said inter-module call instruction triggering execution of a save routine in privilege mode allowing writing to a protected memory which is accessible in read-only mode only except for the save routine, b)- from within the execution of the save routine executing in privilege mode, before branching the execution of the calling module to a precise point in the program of the called module: c)- saving automatically, in the protected memory, with the inter-module call instruction, an identification information used to identify the calling module to programs not executing in privilege mode, said identification information of the calling module consists in the content of one or more registers of the central processing unit in the microprocessor, d)- identifying an identification and program chaining check routine specific to the called module among several identification and program chaining routines, e)- checking whether the calling module is authorised to access the called module, if the calling module is authorised, branching to a specified point of the given called module. c)- saving automatically, in the protected memory, with the inter-module call instruction, an identification information used to identify the calling module to programs not executing in privilege mode, said identification information of the calling module consists in the content of one or more registers of the central processing unit in the microprocessor, d)- identifying an identification and program chaining check routine specific to the called module among several identification and program chaining routines, e)- checking whether the calling module is authorised to access the called module, if the calling module is authorised, branching to a specified point of the given called module.