| 摘要 |
PROBLEM TO BE SOLVED: To provide a programmable controller, which enables a duplexed CPU unit to communicate using the same serial communication programs as a single CPU unit. SOLUTION: A first and a second CPU units 11 and 12 can check internal data transfer and the state of a communication partner through a bus. In addition, the units can communicate with a connection device 20, such as a tool, through a communication cable 21 that corresponds to 1:N communication interface in a serial communication system. Since serial communication port numbers for both of the CPU units are the same, the connection device can communicate without being conscious about whether or not CPU units are active systems. Both of the CPU units can determine whether or not they are active systems, so that the only CPU that is the active system communicates with the connection device. COPYRIGHT: (C)2004,JPO
|
