ngx-modbus-tcp
v1.0.3
Published
Modbus TCP/IP
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Modbus TCP/IP Stream
This is a very simple module that uses NodeJS Streams2 to read Modbus TCP data and convert it to JSON and vice-versa.
Install
npm install ngx-modbus-tcp
Example
var modbus = require("ngx-modbus-tcp");
var client = new modbus.Client();
var server = new modbus.Server();
// link client and server streams together
client.writer().pipe(server.reader());
server.writer().pipe(client.reader());
// if you have a socket (stream) you can just
// call client.pipe(socket) or server.pipe(socket)
server.on("read-coils", function (from, to, reply) {
return reply(null, [ 1, 0, 1, 1 ]);
});
// read coils from unit id = 0, from address 10 to 13
client.readCoils(0, 10, 13, function (err, coils) {
// coils = [ 1, 0, 1, 1 ]
});
Client Methods
All of the following read methods have the form method(unitId, from, to, next)
and write methods have the form method(unitId, addr, val, next)
, where next
is an optional function called if the server replies (with the same transactionId) to the sent message.
- readCoils
- readDiscreteInputs
- readHoldingRegisters
- readInputRegisters
- writeSingleCoil
- writeSingleRegister
- writeMultipleCoils
- writeMultipleRegisters
Addresses are exactly as is in protocol, so if you see a paper talking about address 40001
this usually means first record address of that function so it means address 0
.
Server Events
- read-coils
- read-discrete-inputs
- read-holding-registers
- read-input-registers
- write-single-coil
- write-single-register
- write-multiple-coils
- write-multiple-registers
- data
This last event is triggered when an unknown function code is received.