| 摘要 |
PROBLEM TO BE SOLVED: To provide a device for a PLC that makes it possible to rewrite a program being held during the operation of a program. SOLUTION: The device has a program code area P in which to store a plurality of user applications A, B constituting a program described in C language, and a data area D in which to store programs to be used among the plurality of user applications stored in the program area, as well as a task management program TCB specifying the order of execution of the programs. A variable data mapping block VMB that stores an address for accessing variables stored in a BBS area B is also provided in the data area. By updating an address that shows a program being executed within the TCB during system operation, the user application can be switched from A to B. By changing the reference address of the VMB within the TCB from a solid line to a broken line, the variables for reference can be changed from a, b to c, d. COPYRIGHT: (C)2005,JPO&NCIPI
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