beckhoff-js

This is a Promise based client implementation of the Twincat ADS protocol from Beckhoff written in TypeScript.

API

Connection options

interface ConnectOptions {
  source: {
    netID: string;
    amsPort?: number;
  },
  target: {
    host: string;
    port?: number;
    netID?: string;
    amsPort: number;
  },
  loadSymbols: boolean;
  loadDataTypes: boolean;
  reconnect: boolean;
  reconnectInterval: number;
}

Connect to a PLC and read a tag

const AdsClient = require('beckhoff-js');
 
const options = {
  target: {
    host: "172.16.21.6",
    netID: "5.9.36.191.1.1",
    amsPort: 801
  }
};
 
const client = new AdsClient.default(options);
client
  .connect()
  .then(async () => {
    // Read a tag
    const bTest = await client.readTag(".bTest");
    console.log('bTest value is', bTest);
  });

Connect to a PLC and write a tag

const AdsClient = require('beckhoff-js');
const options = {
  target: {
    host: "172.16.21.6",
    netID: "5.9.36.191.1.1",
    amsPort: 801
  }
};
const client = new AdsClient.default(options);
client
  .connect()
  .then(async () => {
    // write a tag
    return client.writeTag(".bTest", false);
  })
  .catch(err => {
    console.log("failed to write: ", err);
  });

Connect to a PLC and monitor a tag

const AdsClient = require('beckhoff-js');
const options = {
  target: {
    host: "172.16.21.6",
    netID: "5.9.36.191.1.1",
    amsPort: 801
  }
};
const client = new AdsClient.default(options);
client
  .connect()
  .then(async () => {
    // write a tag
    return client.montorTag(".bTest",  (value, timestamp) => {
      console.log(`.bTest value changed ${value} at ${timestamp}`)
    });
  })
  .catch(err => {
    console.log("failed monitor item: ", err);
  });

Events

Client extends EventEmtter and emits following events:

• error Errors. All methods are rejected if they end up with error. Here we have all other errors like connection errors
• connected Connection established (or reconnection)
• reconnect Reconnection started
• close Connection closed

Symbols and tags

The library will automaticly load symbols and tags from the PLC. It will also keep track of sub items of a symbol for you.

All of the following writeTag calls are valid where .Alvalyckan is the symbol and the rest of the path is just sub items. The same is true for all of the Tag functions.

await client.writeTag(".Alvalyckan.HotWaterCount", 3)
await client.writeTag(".Alvalyckan.Alarms.IBJFB_UTOMHUS", false)
await client
  .writeTag(".Alvalyckan.Alarms", {
    IBJFB_KYL: true,
    IBJFB_FRYS: false,
    IBJFB_UTOMHUS: true
  });

Arrays and tags

This library supports Arrays. ST Arrays may have different starting point, Nodejs Arrays startng point is allways 0. If Array starting point is different, all members before that are undefined (<empty item>). Multi dimensional arrays are supported. MultiArray is not supported yet. eg.

 //  arrAlarm: ARRAY [1 .. 2] OF BOOL;
 await client.readTag(".arrAlarm") // [ <1 empty item>, true, true ]

If writing whole array, whole array needs to supplied.

 //  arrAlarm: ARRAY [1 .. 2] OF BOOL;
 await client.writeTag(".arrAlarm". [undefined, false, false])

You can use array indexes for read, write and monitor:

 //  arrAlarm: ARRAY [1 .. 2] OF BOOL;
 await client.readTag(".arrAlarm[1]") // true

Credits, sources and inspiration

There is a lot of projects and information on Beckhoff ADS out there! Below you'll find the ones that has been my primary inspiration and source of information.

• https://github.com/src-one/twincat-ads
• https://github.com/tomcx/tame4
• https://github.com/stlehmann/pyads
• https://github.com/Beckhoff/ADS
• https://github.com/DEMCON/python-ads
• https://github.com/roccomuso/node-ads
• https://github.com/dkleber89/ioBroker.beckhoff
• https://infosys.beckhoff.com/content/1033/tcadsamsspec/html/tcadsamsspec_amstcppackage.htm?id=2322770954845974327