node-beckhoff

Beckhoff ADS/AMS protocol implementation to use as Node.JS library

Heavily inspired on the Node.JS implementation of roccomuso (https://github.com/roccomuso/node-ads) and jisotalo (https://github.com/jisotalo/ads-client)

This library aims to be faster in handling read and write requests by caching the handles to the variables. The library uses async/await and Promises instead of the basic callbacks, so it's a little easier to read and follow.

The calls exposed to the user side provide Promises

Faster handling

Although implementation is still in javascript, execution speed is gained by storing fixed blocks of data (header) and storing handles in a SQLite database (default choice = in-memory)(storing on-disk is also possible but may have performance penalties, depending on the kind of storage used ). The drawback of this is that the application has to restart (or: re-fetch datatypes and symbols) after a PLC code-update.

Handles are stored after first use. When the application terminates, all handles are cleaned upon exit

Commands provided

• getPlcInfo : read plc version
• getPlcState : read current plc state
• getPlcSymbols : read the list of plc symbols -> this step is necessary in order to read and write individual symbols
• getPlcDataTypes : read the list of plc datatypes -> RPC functions are also being fetched _ (they can be used to execute functions rather than write data (still TODO))_
• readPlcData : read the current value of a (list of) specified symbol(s) -> multiple symbols allowed
• writePlcData : set the value of a specified symbol -> multiple symbols allowed
• delPlcHandle : delete a read handle for a symbol -> multiple symbols allowed -> handles are fetched automatically upon read/write/notify
• addPlcNotification : add a notification for a specific symbol -> multiple symbols allowed
• delPlcNotification : remove notifications for a specific symbol -> multiple symbols allowed
• getRpcMethodInfo : fetch info about rpc methods provided -> only 1 method allowed per call -> this requires updated plc datatypes and symbols
• callPlcRpcMethod : call an rpc method on the plc -> only 1 method allowed per call
• destroy : close connection to th PLC. Free used symbol + notify handles.

Example application

A sample console application is provided. This shows the (different) approach for node-ads users and will help new users get started.

Quick-start

const BeckhoffClient = require('node-beckhoff');
const settings = require(__dirname + '/settings.json');

const beckhoff = new BeckhoffClient(settings);

const tmpSettings = beckhoff.settings;

tmpSettings.plc.ip = 'plc-ip';
tmpSettings.remote.netid = 'plc-netid';
tmpSettings.develop.verbose = true;
tmpSettings.develop.debug = false;
beckhoff.settings = tmpSettings;

// fetch plc info
let data = await beckhoff.getPlcInfo();
console.log(JSON.stringify(data));

// fetch all symbols 
data = await beckhoff.getPlcSymbols();
//console.log(JSON.stringify(data)); -> this will produce quite some output
console.log('OK - ' + data.length);

let symbol = [
  { name : 'SENSORS.temp_outside' }
];
data = await beckhoff.readPlcData(symbol);
console.log(JSON.stringify(data));

symbol = [
  { name : 'SENSORS.temp_outside' },
  { name : 'SENSORS.temp_inside' }
];
data = await beckhoff.readPlcData(symbol);
console.log(JSON.stringify(data));

symbol = [
  { name : 'LIGHTS.light_outside', value : 1 }
];
data = await beckhoff.writePlcData(symbol);
console.log(JSON.stringify(data));

/*
 * symbol notifications
 */
beckhoff.on('notify', (data) => {
  console.log(JSON.stringify(data));
})

symbols = [
 // {name : "SENSORS.temp_inside",        mode: "cyclic",   delay : 5, cycle: 30},
  {name : "SENSORS.contact_front_door", mode: "onchange", delay : 5, cycle: 5}
];
data = await beckhoff.addPlcNotification(symbols);
console.log(JSON.stringify(data));

symbols = [
 // {name : "SENSORS.temp_inside"},
  {name : "SENSORS.contact_front_door"}
];
data = await beckhoff.delPlcNotification(symbols);
console.log(JSON.stringify(data));

symbols = [
 // {name : "SENSORS.temp_inside"},
  {name : "SENSORS.contact_front_door"}
];
data = await beckhoff.delPlcNotification(symbols);
console.log(JSON.stringify(data));

// in order to know the syntax for rpc calls on your plc,
// first do a 'getRpcMethodInfo' call
rpcCall = [
  {
    "name" : "LIGHTS.lgt_tabletop",
    "method" : "SET_VALUE", 
    "parm_in" : [{"parm" : "value", "value" : 1}]
  }
];
data = await beckhoff.callPlcRpcMethod(rpcCall);
console.log(JSON.stringify(data));

await beckhoff.destroy();