JP2813277B2 - Sequence control program creation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system program creation method in a sequence control method using a sequential function chart (SFC).

[0002]

2. Description of the Related Art Sequence control of a plurality of operation steps performed by using a programmable sequence controller is easy to change the operation steps and has many advantages, so that it is widely applied in various technical fields. ing. There are ladder diagram systems, flow systems, logic symbol systems, Petri nets, mnemonic systems, table systems, and the like as sequence control languages for creating a program for giving a command to a programmable sequence controller.

[0003] Among these ladder diagram systems, the relay ladder processing system is the best known, but this system is used for repair,
Because of the difficulty in remodeling, a sequence control device and a sequence control language in a graphic expression format have been used.

[0004] A sequential function chart (hereinafter referred to as SF), which is one of languages in a graphic expression format,
C) is an expression form of execution order and processing content in order control common to all languages used for sequence control, and is also an international standard of the International Electrotechnical Commission (IEC), and is therefore expected in the future.

On the other hand, a flow chart or a time chart has conventionally been used for describing the operation processing of the sequence control. Flow charts allow intuitive understanding of the flow of conditions, control, and data processing, but it is difficult to express parallel processing functions, and time charts allow the relationship between the movement of the control target and the processing functions to be understood in parallel, but are structured. There is a drawback that expression is difficult and complicated.

[0006] Since the sequence control is a sequential order control, generally, the description of the operation processing has been performed in a flow chart. However, the flowchart has a drawback that the interrupt operation cannot be described, and the causal relationship of the operation, the branching of the operation mode, and the like are hardly shown.

[0007] Also in this regard, the SFC expresses steps by macro functional blocks, and sequentially describes the steps in detail SF.
Since it is represented by C, structuring is easy. SFC is a notation that can describe the execution order and processing contents of sequence control in a visually understandable manner, and is also a language that facilitates program creation.

FIG. 1 is an explanatory diagram showing a model of an example of a conventional SFC. SFC is a step, transition,
The link is composed of three description elements. The step represents one action, has an active logical state and an inactive logical state, and executes the contents of the action corresponding to one-to-one only in the active state (condition satisfied state).

Each step has a corresponding operation circuit. A transition indicates an execution process transition condition for transitioning from a certain active logical state step to an adjacent inactive logical state step via a link. Each transition has a corresponding transition condition circuit. The link connects the steps and indicates the path of the transition, and includes a simultaneous branch and a selective branch.

As a result, the transition condition corresponding to one-to-one is executed only when the step connected above is in the active state, and the processing result of the transition condition is a logical value “0” or a logical condition “1” (transition condition). The condition is satisfied). An SFC written in such a form can be rewritten to a program of an SFC-compatible sequence control device at any step or transition.

[0011]

The sequence control is a discrete system having asynchronous and parallel properties in which each stage of the control is sequentially advanced according to a predetermined order or an order defined by a certain logic. I can say.

The sequence control is represented by a state equation and an output equation: (1) z (k + 1) = H ｛z (k), v (k)｝ (2) W (k) = Q ｛z (k), v (k)｝.

Here, v is an operation vector to m components, z is a state vector indicating that m components have n internal states, and W is m components and each of them. The output vector in combination with the n internal states of the component, that is, the active / inactive logic state of each step, H and Q indicate matrix functions.

Equation (1) indicates that the internal state of each component in the next step is given by the internal state of each component in the current step and the input. Equation (2) indicates that the output is given from the internal state of each component and the input at that time.

The basic structure of the operation description of the SFC substantially reflects the state equation and the output equation. In addition to the description, it is a very excellent description method of the operation of the sequence control. Is suitable for expressing the order control of the normal operation of.

However, the SFC has a drawback that it is difficult to express conditional logic. The condition logic is a condition that needs to be constantly monitored, and naturally exists in the sequence control system. For example, the SFC can express the processing contents at the time of abnormal operation that is arbitrarily operated. Absent.

The internal condition of each step and each transition is shown as an element indicating the internal state of “the output is given from the internal state of each component and the input at that time” shown in the above-mentioned state equation and output equation. Is still not enough with SFC alone.

That is, the SFC alone cannot accurately represent the operating conditions of the step. Therefore, the interlock cannot be accurately described. The SFC cannot describe the interrupt operation and the operation such as recovery after the interrupt operation, as in the flow chart used to describe the operation processing of the conventional sequence control.

The present invention is a notation system in which the execution order and processing contents of the sequence control are visually easy to understand and can be easily rewritten into a program, which can express the internal state clearly and can sufficiently cope with an interrupt operation and the like. An object of the present invention is to provide a sequence control program creation method.

[0020]

In order to solve the above-mentioned problems, an interlock macro is added to each step and each transition of a sequential fan cushion chart in which conditions that must be constantly viewed are written. By describing the interrupt operation read by the macro and the recovery operation from the interrupt, it is possible to cope with the expression of the conditional logic, that is, the expression of the processing contents at the time of abnormality which is arbitrarily operated.

What is described by RFC are operations and processing conditions which are arbitrarily generated or normally generated. Specifically, troubles, operation mode switching, operation / stop, etc., which are important in sequence control, are described in RFC.

By adding an element called an interlock macro to each step and each transition of the SFC, it is possible to sufficiently express the internal conditions of each step and each transition.

The description method of the operation of the sequence control system of the present invention is based on the SFC, the interlock macro list, and the R
It is constituted by FC. An interlock macro is a constraint condition such as permission or prohibition on operation and operation of the system. Specifically, the operation condition, condition,
It is classified into memory, trouble, failure diagnosis, and safety, and is expressed in a simple description.

[0024]

An embodiment of the present invention will be described with reference to the drawings. FIGS. 2 and 3 are views showing an embodiment of a material handling automatic control system configured using the method for describing the operation of the sequence control system of the present invention.

FIG. 2 shows an operation process of sequence control described in SFC. FIG. 3 shows the correspondence between the step / transition (SFC) and the interlock macro. The operation mode includes three modes: auto, manual, and inching. In the interlock macro in the SFC right column of each mode, trouble, mode switching, operation and stop are described as conditional logic, for example, described as stop of localization value.

FIG. 5 shows a list of interlock macros corresponding to the SFC in which conditions that need to be constantly viewed are described. The contents corresponding to the operating conditions described in the interlock macro of FIG. 3 are collectively described in the macro list of FIG. The operation is held until the conditions of a series of interlock macros are satisfied.

FIG. 4 shows a table type RFC.
The specific operation and operation of the device corresponding to the condition logic read by the interlock macro, which corresponds to the interlock macro condition of FIG. 5, are described.

[0028]

As described above, according to the method for describing the operation of the sequence control system of the present invention, it is possible to accurately describe the operation of the sequence control by the SFC. The interlock macro and the RFC which is read only when required by the interlock macro make it possible to use a conventional SF.
It is possible to complement the interrupt operation and the interrupt recovery operation that C was not good at.

Further, since the interlock macro list is used, the operation conditions of the steps and transitions can be accurately described. The operation described by the method for describing the operation of the sequence control system of the present invention can be easily rewritten to a sequence control program of a ladder diagram system or the like, and thus has an effect of facilitating programming.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a model of an example of a conventional SFC.

FIG. 2 is a diagram showing an SFC in an embodiment of the present invention.

FIG. 3 is a diagram illustrating a correspondence relationship between an SFC and an interlock macro in the embodiment of the present invention.

FIG. 4 is a table type RF according to an embodiment of the present invention.
C is shown.

FIG. 5 is a list of interlock macros according to the embodiment of the present invention.

Claims (2)

(57) [Claims] In a method for creating a sequence control program using a sequential fan cushion chart, an interlock macro is added to each step and each transition of the sequential fan cushion chart in which conditions that need to be constantly viewed are described.
A method for creating a sequence control program, characterized by using a random fan cushion chart describing an interrupt operation read by the interlock macro and a recovery operation from the interrupt. 2. The sequence control program creating method according to claim 1, wherein the random fan cushion chart is a table-type list.