Abstract: A method of controlling a memory including a first storage area and a second storage area. The method includes determining, in response to a request for writing a write data string, whether the write data string changes a logical value stored in the memory from a first logical value to a second logical value, writing, to the first storage area, a logical value that is located in a position of the write data string and does not change an existing logical value of the memory from the first logical value to the second logical value, and writing the second logical value that is located in a position of the write data string and changes an existing logical value of the memory from the first logical value to the second logical value to the second storage area which is different from the first storage area.

Abstract: A method of controlling a memory including a first storage area and a second storage area. The method includes determining, in response to a request for writing a write data string, whether the write data string changes a logical value stored in the memory from a first logical value to a second logical value, writing, to the first storage area, a logical value that is located in a position of the write data string and does not change an existing logical value of the memory from the first logical value to the second logical value, and writing the second logical value that is located in a position of the write data string and changes an existing logical value of the memory from the first logical value to the second logical value to the second storage area which is different from the first storage area.

Abstract: A programmable controller has two communication units connected to a same network and a CPU unit. These two communication units are both identified by same unit-identifying data such as node numbers and unit numbers and function such that one of them operates in an active mode and the other operates in a standby mode. Each of these communication units, when in the active mode, operates to carry out data exchanges with the CPU unit and other nodes connected to the network and, when in standby mode, is prevented from carrying out any data exchange with the other nodes connected to the network. When the communication unit in the active mode fails and goes down, the one in the standby mode is switched to the active mode and carries out the data change. This mode-switching operation is carried out in response to a command from the CPU unit although it may be so arranged that the communication units communicate with each other and switch their modes by informing the occurrence of a failure to the other unit.

Abstract: A communication interface, as a part of a programmable controller, serves to carry out command-response communications with an external general-purpose device connected through a specified communication line according to an execution command from a user program for controlling a control device connected to the programmable controller or according to a preliminarily stored program. When a communication command addressed to an external general-purpose device is received from a peripheral device, it is converted appropriately for communication through a serial line. When it is relayed to the external general-purpose device, it is judged whether it is in a wait condition for a response and the relaying is temporarily stopped. When the wait condition ends, communication is carried out with the external general-purpose and the converted command is relayed to the external general-purpose device.

Abstract: A cleaning tool for an optical connector includes a cylindrical cleaner and a holding member for holding a proximal portion of the cleaner. The cleaner has a main body with a ferrule insertion hole extending from a ferrule insertion port at its distal end face toward the proximal end of the cleaner. The ferrule insertion hole has an inner diameter substantially the same as an outer diameter of a ferrule. The ferrule insertion hole is surrounded by a rough surface so as to clean an outer surface of the ferrule which is to be inserted.

Abstract: A programmable controller has two communication units connected to a same network and a CPU unit. These two communication units are both identified by same unit-identifying data such as node numbers and unit numbers and function such that one of them operates in an active mode and the other operates in a standby mode. Each of these communication units, when in the active mode, operates to carry out data exchanges with the CPU unit and other nodes connected to the network and, when in standby mode, is prevented from carrying out any data exchange with the other nodes connected to the network. When the communication unit in the active mode fails and goes down, the one in the standby mode is switched to the active mode and carries out the data change. This mode-switching operation is carried out in response to a command from the CPU unit although it may be so arranged that the communication units communicate with each other and switch their modes by informing the occurrence of a failure to the other unit.

Abstract: A cleaning tool for an optical connector includes a cylindrical cleaner and a holding member for holding a proximal portion of the cleaner. The cleaner has a main body with a ferrule insertion hole extending from a ferrule insertion port at its distal end face toward the proximal end of the cleaner. The ferrule insertion hole has an inner diameter substantially the same as an outer diameter of a ferrule. The ferrule insertion hole is surrounded by a rough surface so as to clean an outer surface of the ferrule which is to be inserted.