Abstract: A controller continues to operate in a stable manner after program modification. A controller repeatedly executes a task A and a task B in cycles. The controller includes a RAM and a task control program. The RAM stores a fixed time set longer than an actual execution time of the task A as an execution time for the task A. The task control program executes the tasks A and B, and executes the task A by using the fixed time.

Abstract: A controller allows easy synchronization between a plurality of control programs executed in parallel to control a plurality of motors. The control programs are executed cyclically in parallel in predetermined execution cycles. Timing data for synchronizing the execution timing of the control programs is transmitted and received between the control programs. After control program 1 is executed, an axis variable to be referred to by the control program 2 is copied from an execution area of the memory for the control program 1 into a buffer area for the control program 2.

Abstract: A control apparatus capable of updating a user program while processing is being performed in a multitasking manner is provided. A processor includes a memory that stores a user program containing a program organization unit as well as a central processing unit executing a task containing the user program and also updating the program organization unit stored in the memory. The central processing unit is configured to execute a plurality of tasks concurrently and to execute each task with a period corresponding to the task. Moreover, the central processing unit is configured to update the program organization unit stored in the memory during the period of time from when a plurality of tasks to be executed have been finished until when the plurality of tasks are executed again.

Abstract: A technique capable of efficiently performing debugging in a program and checking of soundness in a control system including a controller and a database system. A CPU unit has a communication interface for connection to a database device. The CPU unit executes a user program to call a DB connection service in accordance with an instruction included in the user program and generate a statement to access the database device. In the DB connection service, a statement according to an access instruction is generated, and the generated statement is transmitted to a database system. After that, information indicative of time until a response from the database system is received is acquired, and the acquired information is stored as a log into a memory. A support device acquires the information and displays it on a monitor.

Abstract: A technique for facilitating debugging in a user program which operates by cooperation of a PLC and another system in a control system including a controller and another system. A CPU unit has a communication interface, executes a user program, calls DB connection service in accordance with an instruction included in the user program, and generates a statement to access a database device. In the DB connection service, operation is performed while switching a first mode and a second mode. In the first mode, a statement according to an access instruction is generated, the generated statement is transmitted to a database system, and a result of a response is sent to the user program. In the second mode, without transmitting the statement to the database device, a result of execution corresponding to the statement is sent to the user program.

Abstract: The present invention provides a technique for improving the reliability of access to a database system in a controller, such as a PLC. A PLC accessible to a database accesses a DB server in response to an event in which a user program calls a DB access processing program. The DB access processing program stores status information indicating a status of accesses to the DB server in a nonvolatile memory, in accordance with an instruction of the user program. When a power interruption occurs, the PLC can obtain a status of accesses to the DB server at the timing of the occurrence of the power interruption by referring to the status information. Then, the PLC, for example, re-sends a SQL sentence, depending on the access status.

Abstract: A control device capable of appropriately switching operating modes when multitasking is being performed is provided. A CPU unit is provided with a task executing unit for executing a plurality of tasks in parallel, and for executing each task in cycles based on each task; and a mode switching unit for switching operating modes. The task executing unit is configured in such a manner that when in operation mode, a user program is executed for each task, and when in program mode, a user program is not executed for each task.

Abstract: A control device is provided with a task execution unit, a collection unit which collects variables which have been referenced and updated in a user program and a management unit which manages the collected variables. The user program includes a collection instruction program which instructs the collection of the variables by the collection unit. The collection instruction program further includes distinguishing information for a user to distinguish the location of the collection instruction program in the user program. When the collection of the variables has been instructed by the collection instruction program, the management unit associates the variables collected by the collection unit with the distinguishing information of the collection instruction program.

Abstract: A control device includes a task execution unit; a storage unit which stores a variable in a program, which is capable of being referenced and updated; and a collection unit which collects a variable when a task is executed. The storage unit stores reference data corresponding to the variable. A plurality of tasks include: an update task which is capable of updating and referencing the variable; and a reference task which is capable of referencing the reference data. The collection unit collects the reference data when the plurality of tasks are executed.

Abstract: A control apparatus capable of updating a user program while processing is being performed in a multitasking manner is provided. A processor includes a memory that stores a user program containing a program organization unit as well as a central processing unit executing a task containing the user program and also updating the program organization unit stored in the memory. The central processing unit is configured to execute a plurality of tasks concurrently and to execute each task with a period corresponding to the task. Moreover, the central processing unit is configured to update the program organization unit stored in the memory during the period of time from when a plurality of tasks to be executed have been finished until when the plurality of tasks are executed again.

Abstract: The present invention aims to provide a debug device for efficiently and smoothly performing the debugging process of the control program including function blocks. In the debug device for executing each step configuring the control program including the function blocks one step at a time, a step-over function for continuously executing the program in the function block, and moving the executing position to the step after the execution of the function program in the control program when the next executing position is the function block (FIG. A); a step-in function for having the head position of the program in the function block as the next executing position when the next executing position is the function block; and a step-out function for continuously executing from the next executing position to the end of the function block and moving the executing position to the step after the execution of the function block when the next executing position is the step of the program in the function block are provided.

Abstract: A control system includes a programmable controller having a CPU unit that carries out cyclic operations of processes. An additional temporary user memory is provided in addition to a regular user memory. When an on-line editing of a user program is to be carried out, the program is stored in both memories and the program stored in the temporary memory is called by an instruction execution engine to be executed. After the on-line editing is completed on the user program stored in the user memory, the program execution is based on the edited user program stored in the user memory.

Abstract: A control system includes a programmable controller having a CPU unit that carries out cyclic operations of processes. An additional temporary user memory is provided in addition to a regular user memory. When an on-line editing of a user program is to be carried out, the program is stored in both memories and the program stored in the temporary memory is called by an instruction execution engine to be executed. After the on-line editing is completed on the user program stored in the user memory, the program execution is based on the edited user program stored in the user memory.