modbus-serial
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A pure JavaScript implemetation of MODBUS-RTU (Serial and TCP) for NodeJS.
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JavaScript
;
/* eslint-disable no-undef, no-console */
/**
* Tests require two linked serial connections:
*
* Create two ports /tmp/ttyp0 for the server, /tmp/ptyp0 for the client,
* enable copying to stderr for debugging to see raw messages across connection.
*
* sudo socat -v -x -d -d PTY,link=/tmp/ptyp0,raw,echo=0,ispeed=b9600 PTY,link=/tmp/ttyp0,raw,echo=0,ospeed=b9600
* sudo chown user:user /tmp/ttyp0 /tmp/ptyp0
*/
const { MockBinding } = require("@serialport/binding-mock");
const { SerialPortStream } = require("@serialport/stream");
const expect = require("chai").expect;
// const { SerialPort } = require("serialport");
const ServerSerial = require("./../../servers/serverserial");
// FYI, maximum length for requests.
// const MAX_COIL = 2040;
// const MAX_DISCRETE_INPUT = 2040;
// const MAX_INPUT = 127;
// const MAX_HOLDING_REGISTER = 127;
describe("Modbus Serial Server (no serverID)", function() {
let serverSerial; // eslint-disable-line no-unused-vars
let clientSerial; // eslint-disable-line no-unused-vars
beforeEach(function() {
const vector = {
getInputRegister: function(addr) {
return addr;
},
getHoldingRegister: function(addr) {
if (addr === 62)
throw new Error();
console.log("\tHolding register: ", addr);
return addr + 8000;
},
getCoil: function(addr) {
console.log("\tHolding register: ", addr);
return (addr % 2) === 0;
},
setRegister: function(addr, value) {
console.log("\tset register", addr, value);
return;
},
setCoil: function(addr, value) {
console.log("\tset coil", addr, value);
return;
}
};
MockBinding.createPort("/dev/server", { echo: true, record: true });
MockBinding.createPort("/dev/client", { echo: true, record: true });
clientSerial = new SerialPortStream({
binding: MockBinding,
path: "/dev/client",
baudRate: 9600
});
serverSerial = new ServerSerial(vector, {
binding: MockBinding,
port: "/dev/server",
portResponse: clientSerial,
debug: true
});
});
afterEach(function() {
serverSerial.close();
});
describe("function code handler", function() {
it("should receive a valid Modbus Serial message", function(done) {
let awaitingResponse = false;
clientSerial.write(Buffer.from("01050001ff00ddfa", "hex"));
clientSerial.on("data", function(data) {
if (awaitingResponse === false) {
// Client request forwarded to server
awaitingResponse = true;
serverSerial.getPort().write(data);
} else {
// Client received response
awaitingResponse = false;
// FC05 - valid responce
expect(data.toString("hex")).to.equal("01050001ff00ddfa");
clientSerial.close();
done();
}
});
});
// TODO: FC1 - FCX tests
});
describe("modbus exception handler", function() {
it("should receive a valid unhandled function Modbus Serial message", function(done) {
let awaitingResponse = false;
// FC07 - unhandled function
clientSerial.write(Buffer.from("01070001ff00ddfa", "hex"));
clientSerial.on("data", function(data) {
if (awaitingResponse === false) {
// Client request forwarded to server
awaitingResponse = true;
serverSerial.getPort().write(data);
} else {
// Client received response
awaitingResponse = false;
// A valid error message, code 0x01 - Illegal fanction
expect(data.toString("hex")).to.equal("0187018230");
clientSerial.close();
done();
}
});
});
it("should receive a valid slave failure Modbus Serial message", function(done) {
let awaitingResponse = false;
// FC03 to error triggering address
clientSerial.write(Buffer.from("0103003E0001ddfa", "hex"));
clientSerial.on("data", function(data) {
if (awaitingResponse === false) {
// Client request forwarded to server
awaitingResponse = true;
serverSerial.getPort().write(data);
} else {
// Client received response
awaitingResponse = false;
// A valid error message, code 0x04 - Slave failure
expect(data.toString("hex")).to.equal("01830440f3");
clientSerial.close();
done();
}
});
});
// TODO: exceptions
});
describe("large client request", function() {
it("should handle a large request without crash successfully (FC1)", function(done) {
let awaitingResponse = false;
// request `maximum number` + 1 of coil addresses at once
clientSerial.write(Buffer.from("0101000007f9fe78", "hex"));
clientSerial.on("data", function(data) {
if (awaitingResponse === false) {
// Client request forwarded to server
awaitingResponse = true;
serverSerial.getPort().write(data);
} else {
// Client received response
awaitingResponse = false;
// A valid error message, code 0x04 - Slave failure
expect(data.toString("hex")).to.equal("0181044193");
clientSerial.close();
done();
}
});
});
it("should handle a large request without crash successfully (FC3)", function(done) {
let awaitingResponse = false;
// request `maximum number` + 1 of holding addresses at once
clientSerial.write(Buffer.from("010300000080446a", "hex"));
clientSerial.on("data", function(data) {
if (awaitingResponse === false) {
// Client request forwarded to server
awaitingResponse = true;
serverSerial.getPort().write(data);
} else {
// Client received response
awaitingResponse = false;
// A valid error message, code 0x04 - Slave failure
expect(data.toString("hex")).to.equal("01830440f3");
clientSerial.close();
done();
}
});
});
it("should handle a large request without crash successfully (FC4)", function(done) {
let awaitingResponse = false;
// request `maximum number` + 1 of input addresses at once
clientSerial.write(Buffer.from("010400000080f1aa", "hex"));
clientSerial.on("data", function(data) {
if (awaitingResponse === false) {
// Client request forwarded to server
awaitingResponse = true;
serverSerial.getPort().write(data);
} else {
// Client received response
awaitingResponse = false;
// A valid error message, code 0x04 - Slave failure
expect(data.toString("hex")).to.equal("01840442c3");
clientSerial.close();
done();
}
});
});
// TODO: exceptions
});
describe("too short client request", function() {
it("should handle a request that is too short without crash", function(done) {
// valid ID, function code & CRC, but too short body
serverSerial.getPort().write(Buffer.from("081013bc0f", "hex"));
// wait a bit to make sure we didn't crash
setTimeout(done, 50);
});
});
});
describe("Modbus Serial Server (serverID = requestID)", function() {
let serverSerial; // eslint-disable-line no-unused-vars
let clientSerial; // eslint-disable-line no-unused-vars
before(function() {
const vector = {
setCoil: function(addr, value) {
console.log("\tset coil", addr, value);
return;
}
};
MockBinding.createPort("/dev/server", { echo: true, record: true });
MockBinding.createPort("/dev/client", { echo: true, record: true });
clientSerial = new SerialPortStream({
binding: MockBinding,
path: "/dev/client",
baudRate: 9600
});
serverSerial = new ServerSerial(vector, {
binding: MockBinding,
port: "/dev/server",
portResponse: clientSerial,
debug: true,
unitID: 4
});
});
after(function() {
serverSerial.close();
});
describe("function code handler", function() {
it("should receive a valid Modbus Serial message", function(done) {
let awaitingResponse = false;
// FC05 - force single coil, to on 0xff00
clientSerial.write(Buffer.from("04050001ff00ddaf", "hex"));
clientSerial.on("data", function(data) {
if (awaitingResponse === false) {
// Client request forwarded to server
awaitingResponse = true;
serverSerial.getPort().write(data);
} else {
// Client received response
awaitingResponse = false;
// FC05 - valid responce
expect(data.toString("hex")).to.equal("04050001ff00ddaf");
clientSerial.close();
done();
}
});
});
});
});
describe("Modbus Serial Server (serverID != requestID)", function() {
let serverSerial; // eslint-disable-line no-unused-vars
let clientSerial; // eslint-disable-line no-unused-vars
before(function() {
const vector = {
setCoil: function(addr, value) {
console.log("\tset coil", addr, value);
return;
}
};
MockBinding.createPort("/dev/server", { echo: true, record: true });
MockBinding.createPort("/dev/client", { echo: true, record: true });
clientSerial = new SerialPortStream({
binding: MockBinding,
path: "/dev/client",
baudRate: 9600
});
serverSerial = new ServerSerial(vector, {
binding: MockBinding,
port: "/dev/server",
portResponse: clientSerial,
debug: true,
unitID: 4
});
});
after(function() {
serverSerial.close();
});
describe("function code handler", function() {
it("should receive a no Modbus Serial message for wrong unitID", function(done) {
this.timeout(1000 + 100);
let awaitingResponse = false;
// FC05 - force single coil on unitID 3, to on 0xff00
clientSerial.write(Buffer.from("03050001ff00ddaf", "hex"));
function cleanup() {
clientSerial.close();
done();
}
const timeout = setTimeout(cleanup, 1000);
clientSerial.on("data", function(data) {
if (awaitingResponse === false) {
// Client request forwarded to server
awaitingResponse = true;
serverSerial.getPort().write(data);
} else {
// Client received response
awaitingResponse = false;
clearTimeout(timeout);
clientSerial.close();
expect.fail("Shouldn't have received data - we specified wrong unitID.");
}
});
});
});
});