Diagnostic system and method for detecting retardation of an object controlled by a programmable controller

A method of diagnosing a programmable controller with a diagnostic system having a telecommunication line for connecting to said programmable controller, input means for commanding operations, output means for outputting diagnostic results, and memory means for storing data, comprising the steps of:

• storing output addresses assigned to output ports of said programmable controller from which operational commands for sequentially controlling at least one controlled object are applied to said at least one controlled object, and input addresses assigned to input ports of said programmable controller to which signals representing completion of operations are applied from said at least one controlled object;
• determining whether or not signals representing the completion of operations are applied from said at least one controlled object;
• storing status flags in said memory means when it is determined that said signals representing the completion of operations are applied;
• determining whether or not one series of sequential control is completed;
• resetting data stored in said memory means when it is determined that said one series of sequential control is completed;
• determining whether or not retardations occur in said at least one controlled object;
• transferring control logic, operational commands and signals representing the completion of operations corresponding to said operational commands from said programmable controller when it is determined that said one series of sequential control is completed;
• determining a starting address for analyzing said control logic to identify addresses where retardations occur;
• equivalently modifying a part of said control logic behind said starting address to a form including only external contacts arranged on said at least one controlled object;
• and
• identifying addresses in said control logic where retardations occur in said control logic based on said status flags.

An apparatus for diagnosing a programmable controller comprising:

• means for storing one set of output addresses assigned to output ports of said programmable controller from which one series of operational commands for sequentially controlling at least one controlled object is applied to said at least one controlled object, one set of input addresses assigned to input ports of said programmable controller to which one set of feedback signals corresponding to said one series of operational commands is fed back from said at least one controlled object, and status flags each of which is set, respectively, when each signal of said one set of feedback signals is received by said programmable controller;
• means for determining whether or not retardations occur in said at least one controlled object by checking whether or not all of said status flags are set;
• means for transferring said status flags and control logic programmed in said programmable controller from said programmable controller when it is determined that retardation occurs at said determining step;
• and
• means for identifying an address where a status flag is not set as an address where retardation occurs.

An apparatus for diagnosing a programmable controller comprising:

• memory means for storing output addresses assigned to output ports of said programmable controller from which operational commands for sequentially controlling at least one controlled object are applied to said at least one controlled object, and input addresses assigned to input ports of said programmable controller to which signals representing completion of operations are applied from said at least one controlled object;
• means for determining whether or not signals representing the completion of operations are applied from said at least one controlled object;
• means for storing status flags in said memory means when it is determined that said signals representing the completion of operations are applied;
• means for determining whether or not one series of sequential control is completed;
• means for resetting data stored in said memory means when it is determined that said one series of sequential control is completed;
• means for determining whether or not retardations occur in said at least one controlled object;
• means for transferring control logic, operational commands and signals representing the completion of operations corresponding to said operational commands from said programmable controller when it is determined that said one series of sequential control is completed;
• means for determining a starting address for analyzing said control logic to identify addresses where retardations occur;
• means for equivalently modifying a part of said control logic behind said starting address to a form including only external contacts arranged on said at least one controlled object;
• and
• means for identifying addresses in said control logic where retardations occur in said control logic based on said status flags.