node-mewtocol

Panasonic MEWTOCOL COM protocol implementation for Node-JS

Please use official MEWTOCOL manual as a reference: MEWTOCOL.pdf At the moment only some read commands are implemented:

• RD(station,memory-area,start-addr,end-addr) - Read Registers
• RCS(station,memory-area,address) - Read single Contact binary value
• RCC(station,memory-area,start-addr,end-addr) - Read Contact values as 16bit integers
• RCP(station,addresses-array) - Read up to 8 Contact binary values in a single request
• RS(station,start-addr,end-addr) - Read timer set values
• RK(station,start-addr,end-addr) - Read timer elapsed values
• RR(station,start-addr,end-addr) - Read system register
• RT(station) - Read PLC status

Install

Run the following command in the root directory of your Node.JS application:

npm install jsmewtocol

Run the following command for global install:

npm install -g jsmewtocol

Usage:

const MewClient = require('jsmewtocol');
var ip=10.10.10.11 // ip address of the PLC
var port=9094; // TCP port is optional, default is 9094
var timeout=5000; // timeout is optional, default is 5000ms

const client = new MewClient(ip,port,timeout);
client.on('connect', (server) => { console.log('Event: connected to server: '+server.host+":"+server.port); });
client.on('disconnect', (err) => { console.log('Event: disconnected '+err); }); //the err for disconnect is true if there was an error before disconnecting
client.on('error', (err) => { console.log('Event: error: ' + err.error); }); //err object will contain error details
client.on('timeout', (err) => { console.log('Event: timeout: ' + err.error); }); //err object will contain timeout reason

//If we want to consecutively read different values from the PLC we can use Promises .then construction:
client.RD(1,'D',800,809) // first let's read registers from area D, addresses 800-809 (10 values)
.then ((data)=>{console.log(data); return client.RCS(1,'X','50A');}) // then let's read single bit from Contact area X at address 50, bit #10 (0xA)
.then ((data)=>{console.log(data); return client.RCC(1,'X',100,109);})// then read 16bit Contact values from area X from addresses 100-109 (10 values)
.then ((data)=>{console.log(data); return client.RT(1);}) // then read PLC status
.then ((data)=>{console.log(data); return client.destroy();}) // we need to destroy the connection after we are done reading, otherwise it will wait until socket timeout
.catch ((err) =>{ console.error(err); client.destroy();}); // catch any errors

It is important to destroy the client socket. Otherwise it will hang until PLC drops the connection on it's end or socket timeout will happen. If the socket is destroyed due to timeout, the node-mewtocol will try to re-establish the connection