[Error: EAGAIN: resource temporarily unavailable, read]

[takeruadelbert]

Hi, I need an advice and help.
I can't get any response when sending command to the serial reader.
it seems that the data event not working.
any suggestion what is wrong?

I have tried any solutions from old issues, but no luck so far.

my code:

const SerialPort = require("serialport").SerialPort;

SerialPort.list().then((ports: any) => {

    if (!ports.length) {
        console.error("No serial port found");
        process.exit(1);
    }

    console.log('Using port : ', ports[0].path);

    const serialPort = new SerialPort(
        {
            path: ports[0].path,
            baudRate: 38400,
            dataBits: 8,
            stopBits: 1,
            parity: "none",
            autoOpen: false,
        },
        function (err: any) {
            err && console.error(err);
        }
    );

    serialPort.on('error', (err: string) => {
        console.error('error: ', err);
    });

    serialPort.on('open', () => {
        console.log('Port opened');

        serialPort.on("data", function(data: any) {
            console.log('data', data)
        });

        const temp = Buffer.from([0x02, 0x00, 0x03, 0xEF, 0x01, 0x01, 0x75, 0x8F, 0x40, 0xD4, 0x6D, 0x95, 0xD1, 0x64, 0x14, 0x48, 0xAA, 0x19, 0xB9, 0x28, 0x2C, 0x05, 0xEC]);
        serialPort.write(temp, (err: string) => {
            if (err) {
                console.error('Error sending INIT command:', err);
            } else {
                console.log('INIT command sent successfully.');
            }
        });
    });

    serialPort.open();
});

output from console:

Using port :  COM3
Port opened
INIT command sent successfully.

OS: WIndows 11; Ubuntu 22.04
seriaport version : 12.0.0

[takeruadelbert]

this is the debug log

serialport/bindings-cpp loading LinuxBinding +0ms
  serialport/bindings-cpp list +0ms
Using port :  /dev/ttyUSB0
  serialport/stream opening path: /dev/ttyUSB0 +0ms
  serialport/bindings-cpp open +70ms
  serialport/bindings-cpp/poller Creating poller +0ms
  serialport/stream opened path: /dev/ttyUSB0 +2ms
Port opened
  serialport/stream _write 23 bytes of data +0ms
  serialport/bindings-cpp write 23 bytes +2ms
  serialport/bindings-cpp/unixWrite Starting write 23 bytes offset 0 bytesToWrite 23 +0ms
  serialport/stream _read reading { start: 0, toRead: 65536 } +1ms
  serialport/bindings-cpp read +1ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixWrite write returned: wrote 23 bytes +1ms
  serialport/bindings-cpp/unixWrite Finished writing 23 bytes +0ms
  serialport/stream binding.write write finished +1ms
INIT command sent successfully.
  serialport/bindings-cpp/unixRead read error [Error: EAGAIN: resource temporarily unavailable, read] {
  errno: -11,
  code: 'EAGAIN',
  syscall: 'read'
} +1ms
  serialport/bindings-cpp/unixRead waiting for readable because of code: EAGAIN +0ms
  serialport/bindings-cpp/poller Polling for "readable" +3ms

[takeruadelbert]

after struggling for few days, I can receive the response now.

serialport/bindings-cpp loading LinuxBinding +0ms
  serialport/bindings-cpp list +0ms
Using port :  /dev/ttyUSB0
  serialport/stream opening path: /dev/ttyUSB0 +0ms
  serialport/bindings-cpp open +76ms
  serialport/stream _read queueing _read for after open +0ms
  serialport/bindings-cpp/poller Creating poller +0ms
  serialport/stream opened path: /dev/ttyUSB0 +1ms
Port opened
  serialport/stream _read reading { start: 0, toRead: 65536 } +0ms
  serialport/bindings-cpp read +3ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/stream _write 23 bytes of data +2ms
  serialport/bindings-cpp write 23 bytes +1ms
  serialport/bindings-cpp/unixWrite Starting write 23 bytes offset 0 bytesToWrite 23 +0ms
  serialport/bindings-cpp/unixRead read error [Error: EAGAIN: resource temporarily unavailable, read] {
  errno: -11,
  code: 'EAGAIN',
  syscall: 'read'
} +1ms
  serialport/bindings-cpp/unixRead waiting for readable because of code: EAGAIN +1ms
  serialport/bindings-cpp/poller Polling for "readable" +4ms
  serialport/bindings-cpp/unixWrite write returned: wrote 23 bytes +1ms
  serialport/bindings-cpp/unixWrite Finished writing 23 bytes +0ms
  serialport/stream binding.write write finished +2ms
INIT command sent successfully.
  serialport/bindings-cpp/poller received "readable" +15ms
  serialport/bindings-cpp/unixRead Starting read +15ms
  serialport/bindings-cpp/unixRead Finished read 2 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 2 } +15ms
Received data: <Buffer 02 00>
  serialport/stream _read reading { start: 2, toRead: 65534 } +0ms
  serialport/bindings-cpp read +17ms
  serialport/bindings-cpp/unixRead Starting read +1ms
  serialport/bindings-cpp/unixRead Finished read 3 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 3 } +1ms
Received data: <Buffer 10 00 00>
  serialport/stream _read reading { start: 5, toRead: 65531 } +0ms
  serialport/bindings-cpp read +0ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 2 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 2 } +0ms
Received data: <Buffer 00 00>
  serialport/stream _read reading { start: 7, toRead: 65529 } +0ms
  serialport/bindings-cpp read +0ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 1 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 1 } +0ms
Received data: <Buffer d0>
  serialport/stream _read reading { start: 8, toRead: 65528 } +0ms
  serialport/bindings-cpp read +0ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 2 bytes +1ms
  serialport/stream binding.read finished { bytesRead: 2 } +1ms
Received data: <Buffer 23 09>
  serialport/stream _read reading { start: 10, toRead: 65526 } +0ms
  serialport/bindings-cpp read +1ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 1 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 1 } +0ms
Received data: <Buffer 57>
  serialport/stream _read reading { start: 11, toRead: 65525 } +0ms
  serialport/bindings-cpp read +0ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 1 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 1 } +0ms
Received data: <Buffer 11>
  serialport/stream _read reading { start: 12, toRead: 65524 } +0ms
  serialport/bindings-cpp read +0ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 1 bytes +1ms
  serialport/stream binding.read finished { bytesRead: 1 } +1ms
Received data: <Buffer 62>
  serialport/stream _read reading { start: 13, toRead: 65523 } +0ms
  serialport/bindings-cpp read +1ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead read error [Error: EAGAIN: resource temporarily unavailable, read] {
  errno: -11,
  code: 'EAGAIN',
  syscall: 'read'
} +0ms
  serialport/bindings-cpp/unixRead waiting for readable because of code: EAGAIN +0ms
  serialport/bindings-cpp/poller Polling for "readable" +3ms
  serialport/bindings-cpp/poller received "readable" +0ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 1 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 1 } +0ms
Received data: <Buffer 00>
  serialport/stream _read reading { start: 14, toRead: 65522 } +0ms
  serialport/bindings-cpp read +0ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 2 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 2 } +0ms
Received data: <Buffer 01 09>
  serialport/stream _read reading { start: 16, toRead: 65520 } +0ms
  serialport/bindings-cpp read +1ms
  serialport/bindings-cpp/unixRead Starting read +1ms
  serialport/bindings-cpp/unixRead Finished read 1 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 1 } +1ms
Received data: <Buffer 57>
  serialport/stream _read reading { start: 17, toRead: 65519 } +0ms
  serialport/bindings-cpp read +0ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 1 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 1 } +0ms
Received data: <Buffer 00>
  serialport/stream _read reading { start: 18, toRead: 65518 } +0ms
  serialport/bindings-cpp read +0ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 1 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 1 } +0ms
Received data: <Buffer 09>
  serialport/stream _read reading { start: 19, toRead: 65517 } +0ms
  serialport/bindings-cpp read +0ms
  serialport/bindings-cpp/unixRead Starting read +0ms
  serialport/bindings-cpp/unixRead Finished read 1 bytes +0ms
  serialport/stream binding.read finished { bytesRead: 1 } +0ms
Received data: <Buffer 98>
  serialport/stream _read reading { start: 20, toRead: 65516 } +1ms
  serialport/bindings-cpp read +1ms
  serialport/bindings-cpp/unixRead Starting read +1ms
  serialport/bindings-cpp/unixRead read error [Error: EAGAIN: resource temporarily unavailable, read] {
  errno: -11,
  code: 'EAGAIN',
  syscall: 'read'
} +0ms
  serialport/bindings-cpp/unixRead waiting for readable because of code: EAGAIN +0ms
  serialport/bindings-cpp/poller Polling for "readable" +2ms

it seems the reader has no response if the command was incorrrect (due to incorrect data frame format protocol).