CN108614515B - method for converting PLC ladder diagram into instruction list based on logistics production line control - Google Patents

Abstract

The invention discloses a method for converting a PLC (programmable logic controller) ladder diagram to an instruction list based on logistics production line control, which comprises the steps of S1, adopting a two-way linked list to store ladder diagram information, abstracting vertex information and arc node information in an AOV (automatic optic vision) diagram from the two-way linked list, mapping the AOV diagram into the AOV diagram, S2, adopting step fast scanning to construct a logic tree for the AOV diagram, S3, deleting and combining logic nodes of the logic tree, traversing to generate the instruction list, and S4, outputting the instruction list.

Description

method for converting PLC ladder diagram into instruction list based on logistics production line control

Technical Field

The invention relates to the technical field of PLC (programmable logic controller), in particular to a method for converting a PLC ladder diagram into an instruction list based on logistics production line control.

Background

An important component in the industrial production of the logistics production line, the logistics production line is usually controlled by a PLC (programmable logic controller), and the PLC is usually provided with five languages, wherein a ladder diagram and an instruction list are the two most commonly used languages. Before the PLC generates the target code to be executed by the logistics production line, the conversion from the ladder diagram to the instruction list needs to be completed. When large and complex ladder diagram programs are encountered, the conversion efficiency is low, the program compiling is delayed, and the real-time performance of the control is affected.

Disclosure of Invention

The invention aims to provide methods for converting a PLC ladder diagram to an instruction list based on logistics production line control, which are used for solving the problems of low conversion efficiency and variant program delay when a complex ladder diagram is converted into the instruction list in the prior art.

The invention solves the problems through the following technical scheme:

method for converting PLC ladder diagram to instruction list based on logistics production line control, comprising:

step S1: mapping the ladder diagram into an AOV diagram;

step S2: constructing a logic tree according to the AOV graph;

step S3: traversing the logic tree to generate an instruction list;

step S4: and outputting the instruction table.

Preferably, the step S1 specifically includes:

step S11: establishing a doubly linked list for recording ladder diagram information in an editing process, wherein the ladder diagram information in the editing process comprises rows formed by graphic elements and relations among the rows;

step S12: determining vertex information, wherein the vertex information comprises a vertex number, a vertex position, a vertex number, a vertex arc head, a vertex arc tail, a vertex type and link information;

step S13, determining the direct predecessor and the direct successor of each vertices;

step S14: the complete AOV map is constructed from the vertices, their direct predecessors and successors determined in step S13.

Preferably, the doubly linked list includes an a doubly linked list and a B doubly linked list, the a doubly linked list is used for storing the primitive of each rows in the ladder diagram, and the B doubly linked list is used for storing the relationship between the rows of the ladder diagram.

Preferably, the a doubly linked list includes base elements for storing the ladder primitives and predecessor and successor pointers connecting the base elements.

Preferably, the B doubly linked list includes an up pointer, a down pointer, and a right pointer, the right pointer is used to link the basic units in the a doubly linked list, and the up pointer and the down pointer are used to link different B doubly linked lists.

Preferably, the step S12 specifically includes: and determining the primitives of the ladder diagram as vertexes, regarding the chain line segments between the primitives as arcs, and scanning the ladder diagram sequentially from left to right and from top to bottom so as to determine vertex information.

Preferably, the step S13 specifically includes determining a direct predecessor and a direct successor of each vertices in turn according to the vertex numbers, and the step of determining the direct predecessor and the direct successor of each vertex includes:

step A1: firstly, judging the virtuality and the reality of the current vertex, and jumping to the step A2 if the current vertex is a real vertex; if the vertex is a virtual vertex, jumping to the step A3;

step A2: stopping scanning, determining that the current vertex is a direct precursor, and jumping to the step A4;

step A3: scanning to the left, if a real vertex is found, the real vertex is a direct precursor of the current vertex; stopping scanning if a parallel branch or node is encountered, determining that the current vertex is a direct precursor, and jumping to the step A5;

a4, scanning to the right, finding the next real vertexes, and then the real vertexes are the direct successors of the current vertexes;

step A5: and scanning to the right until a real vertex is found, and the real vertex is a direct successor of the current vertex.

Preferably, the step S2 specifically includes:

step B1: assigning the number of the vertexes to a variable, and traversing the vertexes through a for loop to obtain the degree of entry of the vertexes;

b2, performing the following nodes for circularly traversing the vertexes, and establishing a vertex single linked list;

step B3: sequentially establishing a singly linked list of each vertex according to the method of the step B2, and establishing an adjacency list of the ladder diagram;

step B4: assigning the number of the vertexes to a variable, and traversing the adjacency list in a for loop to obtain the output information of the vertexes;

step B5: and constructing a logic tree for the AOV graph by adopting step fast scanning.

Preferably, the step B5 specifically includes:

scanning from left to right by taking a virtual vertex with zero in-degree as a starting point, if a branch is encountered, scanning a backward directly connected branch, returning to a branch point after the scanning is finished to scan a downward branch, returning to the branch point after the scanning is finished to scan an upward branch, and establishing an th step tree structure after the scanning is finished;

the scan of different steps is repeatedly performed to finally construct tree structures.

Preferably, the step S3 specifically includes:

sequentially judging each logic node on the logic tree, if the type of the logic node is the same as that of a father node of the logic node, directly adding a child node of the logic node as a child node of the father node of the logic node, and deleting the logic node;

and (2) accessing the root node by adopting a for cycle, traversing each sub-tree of the root node according to the sequence from left to right, if the sub-node is traversed, judging whether an element corresponding to the sub-node is input or output, if the element is input, judging whether the element is th sub-node of the father node, if so, generating an LD statement or an LDN statement, otherwise, generating an AND statement or a statement, and if the corresponding element is output, generating an OUT statement.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the invention adopts step fast scanning to construct a logic tree for an AOV graph, a virtual vertex with zero in-degree is taken as a node of a starting point, namely a bus, to start scanning from left to right, if a branch is encountered, a backward directly connected branch is scanned first, a branch point is returned after the scanning is finished to scan a downward or upward branch, a tree structure of th steps is established after the scanning is finished, the scanning of different steps is repeatedly executed to finally construct tree structures, the repetition is reduced, the scanning speed is accelerated, and the conversion efficiency is improved.

(2) The method comprises the steps of establishing a ladder diagram suitable for a dynamic editing double-linked list storage editing process, storing each primitive of the ladder diagram into data of the double-linked list, storing a front relation and a back relation into a pointer field, and linking data exchange between rows through the double-linked list, wherein vertex information and arc node information in the AOV diagram can be abstracted from the double-linked list by using a programming method, and head vertices, tail vertices, numbers of the rows where the vertices are located, columns, vertex arc heads, arc tails and the like are described in a class.

(3) Since the logic nodes are deleted before traversing the logic tree, the scan speed can be further increased by simplifying the AOV graph.

Drawings

FIG. 1 is a structural diagram of a doubly linked list of the present invention;

FIG. 2 is an example ladder diagram employed in an embodiment of the present invention;

FIG. 3 is an AOV graph of the ladder map of FIG. 2;

FIG. 4 is a logic tree constructed in the present invention.

Detailed Description

The present invention is further illustrated in detail with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1:

method for converting PLC ladder diagram to instruction list based on logistics production line control, comprising:

establishing the mapping from the ladder diagram to the AOV diagram, wherein the ladder diagram is as shown in FIG. 2, firstly establishing a double linked list for storing the ladder diagram in the editing process, the ladder diagram is a dynamic editing process and needs to be modified, searched and the like, and the double linked list is suitable for dynamic editing. As shown in fig. 1, each node of the doubly linked list has a successor pointer and a predecessor pointer, and the successor pointer and the predecessor pointer each construct its own linked list of the circular chain. Therefore, each primitive of the ladder diagram can be stored in the data of the double linked list, and the front-back relation of the primitives is stored in the pointer field, so that each row of the ladder diagram is stored, and the data exchange between rows of the ladder diagram can be linked through the double linked list; secondly, the vertex information and arc node information in the AOV graph can be abstracted from the bidirectional linked list by using a programming method, and related information such as head vertices, tail vertex numbers, rows and columns where the vertices are located, vertex arc heads and arc tails and the like exist in the description of the class, so that the information such as the number of the scanned vertices from top to bottom can be obtained from left to right from the starting point of the program; and determining the direct predecessor and the direct successor of the vertex, firstly judging the virtual and real of the vertex in the scanning, stopping scanning if the vertex is a real vertex, wherein the vertex is the direct predecessor, continuing to scan leftwards if the vertex is a virtual vertex until the real vertex is found, and stopping scanning if a parallel branch or a node is met, wherein the virtual vertex is the direct predecessor. And (3) judging direct successor, if the current vertex is a real vertex, scanning rightwards to have a real node, and the vertex is the direct successor: the current vertex is a virtual vertex, and an effective vertex is found to the right direction and is a direct successor of the current vertex; finally, the AOV graph can be constructed by scanning to obtain the determination of the number of the vertexes and the related information of the direct predecessor and the direct successor of the vertexes, as shown in FIG. 3.

A logic tree is built according to an AOV graph, firstly, an adjacency list is adopted to store the AOV graph mapped by a ladder graph, the number of vertexes is assigned to variables, the vertexes are traversed through for circulation to obtain the degree of entry of the vertexes, then, the successor nodes of the vertexes are traversed through for circulation to build single linked lists of vertexes, then, the single linked lists of each vertex are repeatedly built, the adjacency list of the ladder graph is built, finally, for circulation is conducted to obtain the degree of exit information of the vertexes, secondly, the logic tree is built through ladder fast scanning according to the characteristics of a ladder graph program, scanning is started from the nodes of a bus from left to right, if branches are encountered, the branches which are directly connected backwards are scanned, the branches which are scanned downwards or upwards are returned after the scanning is finished, th ladder tree structures are built after the scanning is finished, scanning of different ladders is repeatedly performed, and finally, logic tree structures are built, as shown in FIG. 4, compared with series-parallel.

The method comprises the steps of sequentially judging each logic node on a logic tree, if the type of the logic node is the same as that of a parent node, directly adding a child node of the logic node as the child node of the parent node, deleting the logic node, adopting for-cycle access to a root node, traversing each sub-tree of the root node from left to right, if the logic node is traversed to a child node, judging whether an element corresponding to the child node is input or output, if the element is input, judging whether the element is the th child node of the parent node, if the element is input, generating an LD statement or an LDN statement, otherwise, generating an AND statement or a statement, if the corresponding element is output, generating an OUT statement, and outputting an instruction list as follows:

LD I0.0

A I0.1

LD I0.5

AN I0.6

OLD

O I1.1

LD I0.2

A I0.3

LD I0.7

A I1.0

OLD

ALD

AN I0.4

＝ Q0.0

wherein, LD, get the order, represent and input the open contact order that the bus bar links to each other, namely the open contact logic operation is started;

LDN, negation instruction, representing normally closed contact instructions connected with the input bus, namely the start of logic operation of the normally closed contact;

a, and instruction, for series connection of a single normally open contact;

AN, NAND order, used for the series connection of the single normally closed contact;

o, or command, for parallel connection of a single normally open contact;

OLD, parallel connection instruction of the series circuit blocks, instruction without operation target;

ALD, a serial connection command of parallel circuit blocks, a command without an operation target;

ON, or nor command, for parallel connection of a single normally closed contact.

Although the present invention has been described herein with reference to the illustrated embodiments thereof, which are intended to be preferred embodiments of the present invention, it is to be understood that the invention is not limited thereto, and that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure.

Claims (7)

1, method for converting PLC ladder diagram to instruction list based on logistics production line control, which comprises:

step S1: mapping the ladder diagram into an AOV diagram;

the step S1 specifically includes:

step S11: establishing a doubly linked list for recording ladder diagram information in an editing process, wherein the ladder diagram information in the editing process comprises rows formed by graphic elements and relations among the rows;

step S12: determining vertex information, wherein the vertex information comprises a vertex number, a vertex position, a vertex number, a vertex arc head, a vertex arc tail, a vertex type and link information;

the step S12 specifically includes: determining the primitives of the ladder diagram as vertexes, regarding the chain line segments between the primitives as arcs, and scanning the ladder diagram sequentially from left to right and from top to bottom, so as to determine vertex information

Step S13, determining the direct predecessor and the direct successor of each vertices;

the step S13 specifically includes determining the direct predecessor and the direct successor of each vertices in turn according to the vertex numbers, and the step of determining the direct predecessor and the direct successor of each vertex includes:

step A1: firstly, judging the virtuality and the reality of the current vertex, and jumping to the step A2 if the current vertex is a real vertex; if the vertex is a virtual vertex, jumping to the step A3;

step A2: stopping scanning, determining that the current vertex is a direct precursor, and jumping to the step A4;

step A3: scanning to the left, if a real vertex is found, the real vertex is a direct precursor of the current vertex; stopping scanning if a parallel branch or a node is encountered, determining that the current vertex is a direct precursor, and jumping to the step A5;

a4, scanning to the right, finding the next real vertexes, and then the real vertexes are the direct successors of the current vertexes;

step A5: scanning to the right until finding the real vertex which is the direct successor of the current vertex

Step S14: constructing a complete AOV graph by the determined top points of the step S13, and direct predecessors and successors of the top points; step S2: constructing a logic tree according to the AOV graph;

step S3: traversing the logic tree to generate an instruction list;

step S4: and outputting the instruction table.

2. The method for converting PLC ladder to instruction list based on logistics production line control, wherein said doubly linked list comprises A doubly linked list and B doubly linked list, said A doubly linked list is used for storing primitive of every rows in the ladder, said B doubly linked list is used for storing the relation between rows in the ladder.

3. The method for converting PLC ladder to instruction list based on logistics production line control, wherein the A doubly linked list comprises basic units for storing ladder primitives and a predecessor pointer and a successor pointer for connecting the basic units.

4. The method for converting PLC ladder based on logistics production line control to instruction list, wherein said B doubly linked list comprises up pointer, down pointer and right pointer, said right pointer is used for linking basic unit in said A doubly linked list, said up pointer and down pointer are used for linking different B doubly linked lists.

5. The method for converting the PLC ladder diagram based on logistics production line control into the instruction list, as claimed in any of claims 1-4, wherein the step S2 specifically comprises:

step B1: assigning the number of the vertexes to a variable, and traversing the vertexes through a for loop to obtain the degree of entry of the vertexes;

b2, performing the following nodes for circularly traversing the vertexes, and establishing a vertex single linked list;

step B3: sequentially establishing a singly linked list of each vertex according to the method of the step B2, and establishing an adjacency list of the ladder diagram;

step B4: assigning the number of the vertexes to a variable, and traversing the adjacency list in a for loop to obtain the output information of the vertexes;

step B5: and constructing a logic tree for the AOV graph by adopting step fast scanning.

6. The method for converting PLC ladder diagram to instruction list based on logistics production line control, wherein the step B5 specifically comprises:

scanning from left to right by taking a virtual vertex with zero in-degree as a starting point, if a branch is encountered, scanning a backward directly connected branch, returning to a branch point after the scanning is finished to scan a downward branch, returning to the branch point after the scanning is finished to scan an upward branch, and establishing an th step tree structure after the scanning is finished;

the scan of different steps is repeatedly performed to finally construct tree structures.

7. The method for converting PLC ladder diagram to command sheet based on logistics production line control according to claim 6, wherein the step S3 specifically comprises:

sequentially judging each logic node on the logic tree, if the type of the logic node is the same as that of a father node of the logic node, directly adding a child node of the logic node as a child node of the father node of the logic node, and deleting the logic node;

and (2) accessing the root node by adopting a for cycle, traversing each sub-tree of the root node according to the sequence from left to right, if the sub-node is traversed, judging whether an element corresponding to the sub-node is input or output, if the element is input, judging whether the element is th sub-node of the father node, if so, generating an LD statement or an LDN statement, otherwise, generating an AND statement or a statement, and if the corresponding element is output, generating an OUT statement.

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