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POReading and writing from a serial port in C#, part 2
 

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  1. POReading and writing from a serial port in C#, part 2
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    <p>I am trying to replace a C program with a C# one. The C program connects to an older computer via the COM1 serial port. I do not have any kind of information on how the C code connects to the other machine, but it does connect correctly, so I have to guess as to how it is doing it. I have been using <a href="http://technet.microsoft.com/en-us/sysinternals/bb896644.aspx" rel="nofollow noreferrer">Portmon</a> to try to figure out how the C program is writing and reading successfully. I have also been running Portmon when my new C# application is running. In my C# program, I use the SerialPort class.</p> <p>I am trying to determine what values the different items in the SerialPort class should have by using the output of Portmon on the working program. My thought is that if I can get the values correct for the class, it would write and read correctly. The program (below) is not working correctly. The program opens the COM1 port successfully, but it fails when it tries to write a period (and then another period). These give a timeout.</p> <p>Looking at the output of Portmon running behind the old C program, the working program opened the COM1 port and then wrote one period and then another before reading a successful value (&amp;OK) from the COM1 port. The old program set up several values that I want to duplicate in my C# program.</p> <p>I have tried a variety of combinations of the SerialPort options below, but I obviously have not hit on anything.</p> <p>BTW, I asked some preliminary questions in Stack Overflow question <em><a href="https://stackoverflow.com/questions/14405740">Reading and writing from a serial port in C#, part 2</a></em></p> <p>I am using Windows XP on the machine that is running the programs. The machine on the other side of the COM1 port is a very old PC.</p> <p>Is there a better way to do this? Use something other than Portmon? For the Portmon output for the old program the Process column is ntvdm.exe. Is that a problem? Should I not use the C# SerialPort class? <strong>Probably the most important question is: What values should I use for the Serialport class to match the old program?</strong></p> <p>My C# program:</p> <pre><code>SerialPort comport = new SerialPort(); comport.BaudRate = 9600; comport.DataBits = 7; comport.StopBits = StopBits.One; comport.Parity = Parity.Odd; comport.RtsEnable = true; comport.DtrEnable = true; comport.Handshake = Handshake.RequestToSend; comport.ReadBufferSize = 8192; comport.WriteBufferSize = 100; comport.WriteTimeout = 30000; // 30 sec comport.ReadTimeout = 30000; // 30 sec comport.PortName = "COM1"; string tempFbuffer; byte[] Fbuffer = new byte[200]; string alldata5; tempFbuffer = ".."; for (int cnt = 0; cnt &lt; tempFbuffer.Length; cnt++) { Fbuffer[cnt] = Convert.ToByte(tempFbuffer[cnt]); } comport.Open(); comport.Write(Fbuffer, 0, 1); comport.Write(Fbuffer, 1, 1); for (i = 0; i &lt; 4; i++) { alldata5 = alldata5 + comport.ReadChar(); } comport.Close(); </code></pre> <p>The Portmon output of the application I want to mimic is below. This application connects to the other machine and works correctly. I manually put the headings in at the top.</p> <p>As you can see, on lines 33 and 34 there are successful writes and then on lines 35 and 36, there are successful reads. I ran the program with Portmon in the background.</p> <pre><code># Time Process Reuest Port Result Other 0 0.00004407 ntvdm.exe IRP_MJ_CREATE Serial0 SUCCESS Options: Open 1 0.00000198 ntvdm.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 SUCCESS 2 0.00000115 ntvdm.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS 3 0.00000104 ntvdm.exe IOCTL_SERIAL_GET_CHARS Serial0 SUCCESS 4 0.00000106 ntvdm.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 SUCCESS 5 0.0000008 ntvdm.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 SUCCESS 6 0.00000082 ntvdm.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS 7 0.00000085 ntvdm.exe IOCTL_SERIAL_GET_CHARS Serial0 SUCCESS 8 0.00000081 ntvdm.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 SUCCESS 9 0.00000712 ntvdm.exe IOCTL_SERIAL_SET_BAUD_RATE Serial0 SUCCESS Rate: 1200 10 0.00000349 ntvdm.exe IOCTL_SERIAL_CLR_RTS Serial0 SUCCESS 11 0.00000366 ntvdm.exe IOCTL_SERIAL_CLR_DTR Serial0 SUCCESS 12 0.00000225 ntvdm.exe IOCTL_SERIAL_SET_LINE_CONTROL Serial0 SUCCESS StopBits: 1 Parity: NONE WordLength: 5 13 0.00000111 ntvdm.exe IOCTL_SERIAL_SET_CHAR Serial0 SUCCESS EOF:0 ERR:0 BRK:0 EVT:0 XON:11 XOFF:13 14 0.00000735 ntvdm.exe IOCTL_SERIAL_SET_HANDFLOW Serial0 SUCCESS Shake:0 Replace:0 XonLimit:2048 XoffLimit:512 15 0.00000133 ntvdm.exe IOCTL_SERIAL_LSRMST_INSERT Serial0 SUCCESS Char: ffffffff 16 0.00000338 ntvdm.exe IOCTL_SERIAL_SET_QUEUE_SIZE Serial0 SUCCESS InSize: 8192 OutSize: 100 17 0.00000083 ntvdm.exe IOCTL_SERIAL_GET_TIMEOUTS Serial0 SUCCESS 18 0.00000092 ntvdm.exe IOCTL_SERIAL_SET_TIMEOUTS Serial0 SUCCESS RI:-1 RM:0 RC:0 WM:0 WC:0 19 0.00000349 ntvdm.exe IOCTL_SERIAL_SET_DTR Serial0 SUCCESS 20 0.00000342 ntvdm.exe IOCTL_SERIAL_SET_RTS Serial0 SUCCESS 21 0.00001121 ntvdm.exe IOCTL_SERIAL_SET_BAUD_RATE Serial0 SUCCESS Rate: 1200 22 0.00000262 ntvdm.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR CTS DSR RLSD ERR RING 23 36.94054111 ntvdm.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS 24 0.00000403 ntvdm.exe IOCTL_SERIAL_CLR_DTR Serial0 SUCCESS 25 0.00000356 ntvdm.exe IOCTL_SERIAL_CLR_RTS Serial0 SUCCESS 26 0.00000351 ntvdm.exe IOCTL_SERIAL_SET_DTR Serial0 SUCCESS 27 0.00000348 ntvdm.exe IOCTL_SERIAL_SET_RTS Serial0 SUCCESS 28 0.00000717 ntvdm.exe IOCTL_SERIAL_SET_BAUD_RATE Serial0 SUCCESS Rate: 9600 29 0.00000145 ntvdm.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS 30 0.00000246 ntvdm.exe IOCTL_SERIAL_SET_LINE_CONTROL Serial0 SUCCESS StopBits: 1 Parity: ODD WordLength: 5 31 0.00000086 ntvdm.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS 32 0.00000226 ntvdm.exe IOCTL_SERIAL_SET_LINE_CONTROL Serial0 SUCCESS StopBits: 1 Parity: ODD WordLength: 7 33 0.00002222 ntvdm.exe IRP_MJ_WRITE Serial0 SUCCESS Length 1: . 34 0.00002142 ntvdm.exe IRP_MJ_WRITE Serial0 SUCCESS Length 1: . 35 0.00000562 ntvdm.exe IRP_MJ_READ Serial0 SUCCESS Length 4: &amp;OK. 36 0.00000239 ntvdm.exe IRP_MJ_READ Serial0 SUCCESS Length 0: 37 0.00000533 ntvdm.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS 38 0.0000023 ntvdm.exe IRP_MJ_READ Serial0 SUCCESS Length 0: 39 95.8854497 ntvdm.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS 40 0.00002486 ntvdm.exe IRP_MJ_WRITE Serial0 SUCCESS Length 1: D </code></pre> <p>The Portmon output of the C# application that I am creating is below. The C# code above, when run with Portmon in the background creates this output. I put in the headers.</p> <p>As you can see, there is a timeout error on line 69 during the write. I need this to run close enough to the C one so that the writes and reads work.</p> <p>Obviously the baud rate, wordlength, parity and several others are set correctly.</p> <pre><code># Time Process Reuest Port Result Other 0 0.00004362 fancom.exe IRP_MJ_CREATE Serial0 SUCCESS Options: Open 1 0.0000019 fancom.exe IOCTL_SERIAL_GET_PROPERTIES Serial0 SUCCESS 2 0.00000263 fancom.exe IOCTL_SERIAL_GET_MODEMSTATUS Serial0 SUCCESS 3 0.00000096 fancom.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 SUCCESS 4 0.00000097 fancom.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS 5 0.00000084 fancom.exe IOCTL_SERIAL_GET_CHARS Serial0 SUCCESS 6 0.00000097 fancom.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 SUCCESS 7 0.00000081 fancom.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 SUCCESS 8 0.00000088 fancom.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS 9 0.0000008 fancom.exe IOCTL_SERIAL_GET_CHARS Serial0 SUCCESS 10 0.00000079 fancom.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 SUCCESS 11 0.00000715 fancom.exe IOCTL_SERIAL_SET_BAUD_RATE Serial0 SUCCESS Rate: 9600 12 0.00000355 fancom.exe IOCTL_SERIAL_CLR_DTR Serial0 SUCCESS 13 0.0000024 fancom.exe IOCTL_SERIAL_SET_LINE_CONTROL Serial0 SUCCESS StopBits: 1 Parity: ODD WordLength: 7 14 0.00000107 fancom.exe IOCTL_SERIAL_SET_CHAR Serial0 SUCCESS EOF:1a ERR:3f BRK:3f EVT:1a XON:11 XOFF:13 15 0.00000779 fancom.exe IOCTL_SERIAL_SET_HANDFLOW Serial0 SUCCESS Shake:8 Replace:84 XonLimit:1024 XoffLimit:1024 16 0.0000008 fancom.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 SUCCESS 17 0.00000081 fancom.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS 18 0.00000081 fancom.exe IOCTL_SERIAL_GET_CHARS Serial0 SUCCESS 19 0.00000081 fancom.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 SUCCESS 20 0.00000705 fancom.exe IOCTL_SERIAL_SET_BAUD_RATE Serial0 SUCCESS Rate: 9600 21 0.00000349 fancom.exe IOCTL_SERIAL_SET_DTR Serial0 SUCCESS 22 0.0000022 fancom.exe IOCTL_SERIAL_SET_LINE_CONTROL Serial0 SUCCESS StopBits: 1 Parity: ODD WordLength: 7 23 0.00000098 fancom.exe IOCTL_SERIAL_SET_CHAR Serial0 SUCCESS EOF:1a ERR:3f BRK:3f EVT:1a XON:11 XOFF:13 24 0.00000493 fancom.exe IOCTL_SERIAL_SET_HANDFLOW Serial0 SUCCESS Shake:9 Replace:84 XonLimit:1024 XoffLimit:1024 25 0.00000684 fancom.exe IOCTL_SERIAL_SET_DTR Serial0 SUCCESS 26 0.00000108 fancom.exe IOCTL_SERIAL_SET_TIMEOUTS Serial0 SUCCESS RI:-1 RM:-1 RC:30000 WM:0 WC:30000 27 0.00000227 fancom.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR RXFLAG CTS DSR RLSD BRK ERR RING 28 35.62327662 fancom.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS 29 0.00000399 fancom.exe IOCTL_SERIAL_SET_QUEUE_SIZE Serial0 SUCCESS InSize: 8192 OutSize: 100 30 30.00157726 fancom.exe IRP_MJ_WRITE Serial0 TIMEOUT Length 1: . 31 0.00000767 fancom.exe IRP_MJ_FLUSH_BUFFERS Serial0 SUCCESS 32 0.00001012 fancom.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: 33 0.00000402 fancom.exe IOCTL_SERIAL_CLR_DTR Serial0 SUCCESS 34 0.00000116 fancom.exe IRP_MJ_FLUSH_BUFFERS Serial0 SUCCESS 35 0.0000023 fancom.exe IOCTL_SERIAL_PURGE Serial0 SUCCESS Purge: RXABORT RXCLEAR 36 0.00000163 fancom.exe IOCTL_SERIAL_PURGE Serial0 SUCCESS Purge: TXABORT TXCLEAR 37 0.00000404 fancom.exe IRP_MJ_CLEANUP Serial0 SUCCESS 38 0.00322359 fancom.exe IRP_MJ_CLOSE Serial0 SUCCESS 39 0.00004607 fancom.exe IRP_MJ_CREATE Serial0 SUCCESS Options: Open 40 0.00000188 fancom.exe IOCTL_SERIAL_GET_PROPERTIES Serial0 SUCCESS 41 0.00000277 fancom.exe IOCTL_SERIAL_GET_MODEMSTATUS Serial0 SUCCESS 42 0.00000092 fancom.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 SUCCESS 43 0.00000112 fancom.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS 44 0.0000008 fancom.exe IOCTL_SERIAL_GET_CHARS Serial0 SUCCESS 45 0.00000093 fancom.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 SUCCESS 46 0.00000079 fancom.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 SUCCESS 47 0.00000085 fancom.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS 48 0.00000081 fancom.exe IOCTL_SERIAL_GET_CHARS Serial0 SUCCESS 49 0.00000082 fancom.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 SUCCESS 50 0.00000704 fancom.exe IOCTL_SERIAL_SET_BAUD_RATE Serial0 SUCCESS Rate: 9600 51 0.00000352 fancom.exe IOCTL_SERIAL_CLR_DTR Serial0 SUCCESS 52 0.00000225 fancom.exe IOCTL_SERIAL_SET_LINE_CONTROL Serial0 SUCCESS StopBits: 1 Parity: NONE WordLength: 8 53 0.00000113 fancom.exe IOCTL_SERIAL_SET_CHAR Serial0 SUCCESS EOF:1a ERR:0 BRK:0 EVT:1a XON:11 XOFF:13 54 0.00000489 fancom.exe IOCTL_SERIAL_SET_HANDFLOW Serial0 SUCCESS Shake:8 Replace:80 XonLimit:1024 XoffLimit:1024 55 0.00000084 fancom.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 SUCCESS 56 0.00000083 fancom.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 SUCCESS 57 0.00000081 fancom.exe IOCTL_SERIAL_GET_CHARS Serial0 SUCCESS 58 0.00000081 fancom.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 SUCCESS 59 0.00000696 fancom.exe IOCTL_SERIAL_SET_BAUD_RATE Serial0 SUCCESS Rate: 9600 60 0.00000344 fancom.exe IOCTL_SERIAL_SET_DTR Serial0 SUCCESS 61 0.00000222 fancom.exe IOCTL_SERIAL_SET_LINE_CONTROL Serial0 SUCCESS StopBits: 1 Parity: NONE WordLength: 8 62 0.00000102 fancom.exe IOCTL_SERIAL_SET_CHAR Serial0 SUCCESS EOF:1a ERR:0 BRK:0 EVT:1a XON:11 XOFF:13 63 0.00000474 fancom.exe IOCTL_SERIAL_SET_HANDFLOW Serial0 SUCCESS Shake:9 Replace:80 XonLimit:1024 XoffLimit:1024 64 0.00000345 fancom.exe IOCTL_SERIAL_SET_DTR Serial0 SUCCESS 65 0.00000081 fancom.exe IOCTL_SERIAL_SET_TIMEOUTS Serial0 SUCCESS RI:-1 RM:-1 RC:30000 WM:0 WC:30000 66 0.00000192 fancom.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: RXCHAR RXFLAG CTS DSR RLSD BRK ERR RING 67 30.00755135 fancom.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 SUCCESS 68 0.00000353 fancom.exe IOCTL_SERIAL_SET_QUEUE_SIZE Serial0 SUCCESS InSize: 8192 OutSize: 100 69 29.99287343 fancom.exe IRP_MJ_WRITE Serial0 TIMEOUT Length 1: . 70 0.00000349 fancom.exe IRP_MJ_FLUSH_BUFFERS Serial0 SUCCESS 71 0.00000985 fancom.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 SUCCESS Mask: </code></pre>
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    1. COcheck and read about StopBits.One. 1 != StopBits.One
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    2. CO@gabba I don't understand that comment. How is StopBits.One != 1? It's not equal to 1 what? It's certainly equal to 1 stop bit.
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      1. POReading and writing from a serial port in C#, part 2
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    3. COYou haven't made much of an effort to get the PortMon output to match between the two programs. The critical mismatch is the Handshake property.
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