Jtekt Corporation

Kenichi Ikegami

Tsutomu Araki

A programming assist device for a PLC program and a programming assist method for a PLC program capable of easily preparing separate executable files for causing redundant CPUs of a PLC to operate and reliably preventing an emergency stop of the PLC due to a failure in converter software are provided. First and second intermediate codes are generated from an original program. An inverse conversion program is generated from the first intermediate code. A reconverted first intermediate code and a reconverted second intermediate code are generated from the inverse conversion program. In the case where the intermediate codes and the reconverted intermediate codes match each other, a first executable file is generated from the reconverted first intermediate code, and a second executable file is generated from the reconverted second intermediate code. The executable files are transferred to the PLC.

Programming assist device for programmable logic controller program and programming assist method for the program

A method of inspecting a RAM of a programmable logic controller is provided that enables all unit storage regions in a RAM inspection region to be inspected in about several minutes and that meets a predetermined safety standard. The inspection method includes the steps of: (a) dividing a RAM inspection region, which is a region of the RAM to be inspected, into a plurality of blocks; and (b) by a control device, writing a predetermined value into unit storage regions in a combination of blocks obtained by combining two blocks extracted from the divided blocks and thereafter sequentially inspecting whether or not values read from the unit storage regions each coincide with the written value. Step (b) is executed for all combinations of two blocks extracted from the divided blocks.

Method of inspecting RAM of programmable logic controller, and programmable logic controller

A common library stores therein user function blocks and ready-made protected function blocks. By being manipulated by the user, an editing device links some of function programs stored in the function blocks in the library to form a control program which controls the exchange of signals between I/O modules and external devices. A control section in the terminal device allows the alteration of the function programs included in the user function blocks, but inhibits the alteration of the function programs included in the protected function blocks.

Program editing device for programmable controller

The PLC according to this invention includes I/O modules, a CPU module, an input/output bus, and a PC having a display. The CPU module includes a control program storage unit which previously stores an intrinsic control program in which operation processing and an input/output information item are packaged; a library which previously stores the function block representing the operation processing; and a header file which previously stores equivalent input/output information equivalently representing the input/output information by a graphical language. Referring to the library and header file, PC causes the execution program created and stored in the main storage unit to be displayed on the display by the function block and equivalent input/output information item.

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Inazawa, Japan

Kenichi Ikegami