Problems recording serialports nodejs?
I am using the serialports nodejs module ( https://npmjs.org/package/serialport ) and I am having problems writing to the serial port.
If I just write to the port like below, the serial device never gets the command.
var serialport = require("serialport");
var sp = new serialport.SerialPort(serialPortPath);
sp.write("SYST:ADDR?\n");
However, if I use setTimeout like below does it work?
var serialport = require("serialport");
var sp = new serialport.SerialPort(serialPortPath);
setTimeout(function(){sp.write("SYST:ADDR?\n")},1000);
FYI, "serialPortPath" is installed elsewhere in the code.
I'm not sure what's going on ... any ideas?
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Here's another approach that works very well and allows dynamic addressing of a specific serial device. In my case, I'm only interested in connecting to a Numato device connected to our integrated system, so I have the conditional logic in the list callback.
exports.testSerial = function(data) {
serialPort.list(function(err, ports) {
var port = {};
for(var i = 0; i < ports.length; i++) {
try {
if(typeof ports[i].manufacturer != 'undefined' && ports[i].manufacturer.includes("Numato")) {
port = ports[i];
}
} catch(err) {
console.dir(err);
}
}
// the port will be opened via the constructor of this call
var numato = new serial(port.comName, {baudrate : 19200}, function(err) {
if(err) {
return console.dir(err);
}
// by having the write call within the callback you can access it directly w/o using .on()
numato.write('relay ' + data.state + ' ' + data.channel + '\r', function(err) {
if(err) {
console.dir('error writing');
console.dir(err);
}
console.dir('serial message written');
numato.close();
});
});
return true;
});
}
Hope this helps someone in the future! For reference this is with library version 4.0.7.
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I think I figured it out from github ( https://github.com/voodootikigod/node-serialport page ... basically it looks like I was missing "open" like below:
serialPort.on("open", function () {
console.log("open");
serialPort.on("data", function(data) {
console.log("data received: " + data);
});
serialPort.write("SYST:ADDR?\n", function(err, results) {
console.log("err: " + err);
console.log("results: " + results);
});
});
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