Patent ID: 7536590
Filing Date: 2009-05-19
Classification: G05B,G06F

Abstract:
1. A programmable controller comprising: two CPU units, each of said two CPU units being adapted to know status of the other of said CPU units, one of said two CPU units functioning as an executing CPU unit and the other of said two CPU units functioning as a standby CPU unit, said standby CPU unit being adapted, when said executing CPU unit goes down, to serve as said executing CPU unit and to continue operations of said executing CPU unit, each one of said two CPU units storing a user program, user program version data based on said user program and unit version data indicative of functionality of said one CPU unit, wherein each of said two CPU units comprises: judging means for judging, based on the unit version data of said standby CPU unit and the user program version data stored in said executing CPU unit, whether or not execution of the user program stored in said executing CPU unit is possible by said standby CPU unit; and starting means for starting a duplexed operation by said two CPU units only if said judging means judges that said execution is possible; wherein the judging means of said executing CPU unit has the functions of: obtaining the unit version data of said standby CPU unit from said standby CPU unit; and judging whether or not the user program stored in said executing CPU unit can be executed by said standby CPU unit by comparing the obtained unit version data of said standby CPU unit with said user program stored in said executing CPU unit; and wherein said executing CPU unit has the function of copying said user program stored in said executing CPU unit to said standby CPU unit together with said user program version data when starting said duplexed operation; and wherein said executing CPU unit is adapted to obtain the unit version data of said standby CPU unit, compare said obtained unit version data of said standby CPU unit with the unit version data of said executing CPU unit and to communicate an older of the compared unit version data to a support tool connected to said programmable controller.