| 摘要 |
A programmable controller (PLC) facilitates modifications to programs running thereon, readily accommodates addition and removal of intelligent modules contained therein, and offers good maintenanceability. For modifying programs in a conventional PLC which incorporates intelligent modules, programs in each of the intelligent modules must be modified since programs are individually inputted to the respective intelligent modules, thus giving rise to a problem in that an increased amount of works are required. In the PLC of the present invention, a processing unit of an intelligent module is configured equivalent to a processing unit of a CPU module, and registers and memories of respective intelligent modules are allocated in a memory map of the CPU module to build a hardware configuration which allows the processing unit of the CPU module to read and write the registers and memories of the respective intelligent modules, so that the intelligent modules can be controlled in a manner similar to the CPU module. Software running on the CPU module is additionally provided with instructions which indicate that they are executed in an intelligent module but can be processed either by the CPU module or by the intelligent module.
|
