nestjs S71200 连接 单个地址读写 多个地址读写 断连重连

连接S71200 PLC可以使用node-snap7库来实现。以下是一个简单的例子：

import { Injectable } from '@nestjs/common';
import * as snap7 from 'node-snap7';

@Injectable()
export class PlcService {
  private plcClient: snap7.S7Client;

  constructor() {
    this.plcClient = new snap7.S7Client();
  }

  async connect(ip: string, rack: number, slot: number): Promise<void> {
    return new Promise<void>((resolve, reject) => {
      this.plcClient.connect(ip, rack, slot, (err) => {
        if (err) {
          reject(err);
        } else {
          resolve();
        }
      });
    });
  }

  async disconnect(): Promise<void> {
    return new Promise<void>((resolve, reject) => {
      this.plcClient.disconnect((err) => {
        if (err) {
          reject(err);
        } else {
          resolve();
        }
      });
    });
  }

  async readSingleByte(db: number, start: number): Promise<number> {
    return new Promise<number>((resolve, reject) => {
      this.plcClient.readArea(snap7.S7AreaDB, db, start, 1, snap7.S7Word, (err, data) => {
        if (err) {
          reject(err);
        } else {
          resolve(data[0]);
        }
      });
    });
  }

  async writeSingleByte(db: number, start: number, value: number): Promise<void> {
    return new Promise<void>((resolve, reject) => {
      const buffer = Buffer.alloc(1);
      buffer.writeUInt8(value);
      this.plcClient.writeArea(snap7.S7AreaDB, db, start, buffer.length, snap7.S7Word, buffer, (err) => {
        if (err) {
          reject(err);
        } else {
          resolve();
        }
      });
    });
  }

  async readMultipleBytes(db: number, start: number, length: number): Promise<Buffer> {
    return new Promise<Buffer>((resolve, reject) => {
      this.plcClient.readArea(snap7.S7AreaDB, db, start, length, snap7.S7Word, (err, data) => {
        if (err) {
          reject(err);
        } else {
          const buffer = Buffer.alloc(length * 2);
          for (let i = 0; i < length; i++) {
            buffer.writeUInt16BE(data[i], i * 2);
          }
          resolve(buffer);
        }
      });
    });
  }
}

在上面的代码中，我们使用了node-snap7库来连接S71200 PLC，并实现了读写单个字节和多个字节数据的方法。连接方法使用了Promise来处理异步操作，而读写方法则是通过回调函数来获取结果。

使用该服务的方法如下：

@Injectable()
export class AppService {
  constructor(private plcService: PlcService) {}

  async readSingleByte(db: number, start: number): Promise<number> {
    await this.plcService.connect('192.168.0.1', 0, 1);
    const result = await this.plcService.readSingleByte(db, start);
    await this.plcService.disconnect();
    return result;
  }

  async writeSingleByte(db: number, start: number, value: number): Promise<void> {
    await this.plcService.connect('192.168.0.1', 0, 1);
    await this.plcService.writeSingleByte(db, start, value);
    await this.plcService.disconnect();
  }

  async readMultipleBytes(db: number, start: number, length: number): Promise<Buffer> {
    await this.plcService.connect('192.168.0.1', 0, 1);
    const result = await this.plcService.readMultipleBytes(db, start, length);
    await this.plcService.disconnect();
    return result;
  }
}

在上面的代码中，我们创建了一个AppService类来使用PlcService类，并实现了读写单个字节和多个字节数据的方法。在每个方法中，我们先调用connect方法连接PLC，然后调用相应的读写方法，最后再调用disconnect方法断开连接。这样可以确保每个方法都是在PLC连接的情况下执行的，并且在执行完毕后断开连接，以免占用资源。