SWITCHING METHOD OF HOLDING DOUBLE PROGRAMMABLE CONTROLLER

摘要

PURPOSE:To attain the switching of a programmable controller together with the continuous control even in case a peripheral device has a fault, by putting the programmable controller itself under a simulated fault mode and switching it to a holding system in the fault mode of the peripheral device. CONSTITUTION:A holding double system contains a programmable controller 10 having a diagnosis function for the controller 10 itself and an automatic switching function which performs automatic switch to a holding system 20 when a fault is confirmed by said diagnosis function and a peripheral device connected to the controller 10. The control sequences of both controllers 10 and 20 of the holding double system are provided with a fault monitor function for the peripheral device. When the peripheral device has a fault, the controller 10 itself is put under a simulated state by the control sequence of the controller 10. Thus the controller 10 is switched automatically to the holding controller 20 by the automatic switching function of the controller 10.