Programmable controller alarm display method

Claim 1

An alarm display method in a programmable controller for controlling an apparatus, the controller having a memory for storing a sequence program in which messages are programmed, a processor for performing sequence control by successively executing the sequence program stored in said memory, and a display unit for displaying a ladder diagram corresponding to the sequence program of said memory as well as the messages, said method comprising the steps of: (a) determining alarm conditions for the apparatus (b) generating display information representing a ladder diagram for a sequence program associated with each of said alarm conditions; (c) generating a sequence program for the apparatus, including ladder data specifying said display information for each of said alarm conditions, and data defining a message for each of said alarm conditions; (d) executing said sequence program to control the apparatus; (e) sensing execution of the sequence program; (f) accessing the memory to retrieve the display information associated with the sensed alarm condition on the basis of the ladder data within said sequence program; and (g) displaying on the display unit the ladder diagram represented by the accessed display information, together with the message associated with the sensed alarm condition.