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POConvert serial port application from C# to C in visual studio (ERROR_INVALID_PARAMETER) 87
 

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  1. POConvert serial port application from C# to C in visual studio (ERROR_INVALID_PARAMETER) 87
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    <p>I am trying to write an app in C to communication with a device through a COM port.</p> <p>I am able to send data using Docklight (hyper terminal like program) with the following settings and I can verify that I am receiving it through Itronix LogicPort Logic Analyzer. Baud rate:9600 Parity:None Byte Size:8 Stop bits:1</p> <p>I am having 2 problems with my C program: 1) sometimes CreateFile returns INVALID_HANDLE_VALUE and the other problem I can't seem to get by is that GetCommState() SetCommState() SetCommTimeouts() always return ERROR_INVALID_PARAMETER 87 (0x57)</p> <p>Since I couldn't get past this problem, I tried a program in C# and that works just fine, but my program must be in C to communicate with the rest of my code. This program also communicates with other programs in C through sockets.</p> <p>in Device Manager the device I want to talk to is listed as COM6 under Ports(COM &amp; LPT)</p> <p>any help would be appreciated!</p> <p>Below is the code for both programs:</p> <pre><code>using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.IO.Ports; namespace WindowsFormsApplication1 { public partial class Form1 : Form { byte[] TxBuffer = new byte[20]; SerialPort CommPort = new SerialPort("COM6", 9600, Parity.None, 8, StopBits.One); public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { CommPort.Open(); TxBuffer[0] = (byte)'|'; TxBuffer[1] = 0; TxBuffer[2] = 0; TxBuffer[3] = 0; TxBuffer[4] = 1; TxBuffer[5] = 100; TxBuffer[6] = 1; TxBuffer[7] = 6; TxBuffer[8] = (byte)'|'; TxBuffer[9] = 1; } private void button1_Click(object sender, EventArgs e) { CommPort.Write(TxBuffer, 0, 10); } } } </code></pre> <p>and the C code is:</p> <p>somewhere </p> <pre><code> struct serial_dev { HANDLE hSerial; }; struct serial_dev sdev; //global //somewhere in main if (init_serial(&amp;sdev, com_file) == -1) return -1; write_ser(&amp;sdev, buffer, buf_size); close_serial(&amp;sdev); // in serial.c int init_serial(struct serial_dev *sdev, char *port_name) { DCB dcbSerialParams; COMMTIMEOUTS timeouts; int error = 0; memset(&amp;dcbSerialParams, 0, sizeof(dcbSerialParams)); memset(&amp;timeouts, 0, sizeof(timeouts)); sdev-&gt;hSerial = CreateFile("COM6", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL); if (sdev-&gt;hSerial == INVALID_HANDLE_VALUE) { error = GetLastError(); close_serial(sdev); fprintf(stderr, "error: could not open serial port (error:%d)\n", error); return -1; } memset(&amp;dcbSerialParams, 0, sizeof(dcbSerialParams)); dcbSerialParams.DCBlength = sizeof(dcbSerialParams); if (!GetCommState(sdev-&gt;hSerial, &amp;dcbSerialParams)) { close_serial(sdev); error = GetLastError(); fprintf(stderr, "error: could not get serial port state (%d)\n", error); return -1; } dcbSerialParams.BaudRate = CBR_9600; dcbSerialParams.ByteSize = 8; dcbSerialParams.StopBits = ONESTOPBIT; dcbSerialParams.Parity = NOPARITY; if (!SetCommState(sdev-&gt;hSerial, &amp;dcbSerialParams)) { close_serial(sdev); error = GetLastError(); fprintf(stderr, "error: could not set serial port state (%d)\n", error); return -1; } timeouts.ReadIntervalTimeout = 50; timeouts.ReadTotalTimeoutConstant = 200; timeouts.ReadTotalTimeoutMultiplier = 10; timeouts.WriteTotalTimeoutConstant = 50; timeouts.WriteTotalTimeoutMultiplier = 10; if (!SetCommTimeouts(sdev-&gt;hSerial, &amp;timeouts)) { close_serial(sdev); error = GetLastError(); fprintf(stderr, "error: could not set serial port timeouts (%d)\n", error); return -1; } return 0; } void close_serial(struct serial_dev *sdev) { CloseHandle(sdev-&gt;hSerial); } int write_ser(struct serial_dev *sdev, void *buf, size_t len) { DWORD written; BOOL success; success = WriteFile(sdev-&gt;hSerial, buf, len, &amp;written, NULL); if(!success || written == 0) { printf("error writing to serial\n"); return -1; } printf("writing to serial OK!\n"); return written; } </code></pre>
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    1. USdsolimano
    1. USemge
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      1. POConvert serial port application from C# to C in visual studio (ERROR_INVALID_PARAMETER) 87
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      1. VTUpMod
    1. COYou should report the GetLastError value, when CreateFile returns INVALID_HANDLE_VALUE. This can be a problem that the port has not been closed before.
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      1. POConvert serial port application from C# to C in visual studio (ERROR_INVALID_PARAMETER) 87
      1. USharper
    2. CONote: you should use "\\.\COM6" for the CreateFile (not sure it will change anything).
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      1. POConvert serial port application from C# to C in visual studio (ERROR_INVALID_PARAMETER) 87
      1. USSimon Mourier
    3. CO@harper - I am doing that already in the code posted
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      1. POConvert serial port application from C# to C in visual studio (ERROR_INVALID_PARAMETER) 87
      1. USemge
 

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