Serial Communication - ReadFile returns WriteFile buffer

[georgek01]

Hello!

I've successfully developed an application that sends text messages via my GSM phone connected to my computer (USB).

What I'm unable to do though is read responses from the modem. After I issue a WriteFile, I wait two seconds then issue a ReadFile. All I get back is the WriteFile buffer contents. How do I read the response from the port directly after a WriteFile?

I'm communicating with the modem synchronously.

[dedndave]

http://www.codeproject.com/KB/cs/SMS.aspx?fid=457949&df=90&mpp=25&noise=3&sort=Position&view=Quick&select=3062048&fr=76

[Farabi]

I had a CDMA Haier c 6000 can I use that library too?

[dedndave]

http://www.mygsmfriends.com/drivers-pinout-f233/haier-c-5000-and-c-6000-unlock-without-computer-t13.htm

gsm is gsm - at commands are at commands
i would think you should be able to use it

[georgek01]

My question was less around sending and receiving text messages and more around using ReadFile after a WriteFile.

Lets take SMS & GSM out of the question....  :P

I'm using WriteFile to send an AT command. After that I want to read the response from the modem e.g. ERROR, OK etc.

When I issue the ReadFile after a WriteFile I get the contents of the WriteFile buffer back, even if I delay the read for a few seconds.

How do I read the port after a write without reading in the write buffer?

[dedndave]

ReadFile should work
show us a small snippet of code

[georgek01]

I start by setting the SIM PIN. Once the PIN command is sent i want to pick up on the response from the modem i.e. ERROR or OK.

Code Select Expand


szConfig1 db 'at+cpin=%s',13,10,0
szConfig2 db 'at+cmgf=1',13,10,0
szSend1 db 'at+cmgs="%s"',13,10,0
szSend2 db '%s',26,0

; get the SIM PIN from the text box
invoke GetDlgItemText,hDlg,1008,addr buffer1,sizeof buffer1
invoke wsprintf,addr buffer2,addr szConfig1, addr buffer1

; write the pin to the file handle
invoke WriteFile,hConn,addr buffer2,sizeof buffer2,addr bytes,NULL

; write was successful if not 0
.if eax == 0
   invoke ErrMsg,hDlg,16,0,addr szAppName
   xor eax,eax
   ret
.endif

; at this point I send a ReadFile to pick up the ERROR or OK response from the modem, but
; the read just returns the contents of the buffer from the write operation

invoke RtlZeroMemory,addr buffer3,sizeof buffer3

; get response from the modem
invoke ReadFile,hConn,addr buffer3,sizeof buffer3,addr dwBytes,NULL
   .if eax != 0
      .if dwBytes != 0

         ; [** problem **] buffer3 contains the data from the previous write operation
         invoke MessageBox,hDlg,addr buffer3,addr buffer3,0

      .else
         invoke ErrMsg,hDlg,27,0,addr szAppName
         invoke LocalFree,hMem
         ret
      .endif
  .else
      invoke ErrMsg,hDlg,37,0,addr szAppName
      invoke LocalFree,hMem
      ret
.endif



[dedndave]

maybe it has to do with how the port is configured
http://msdn.microsoft.com/en-us/library/aa450602.aspx

i don't mess with my own phone, but i have had to play with some of this in the past for a contract
i was using 16-bit code, though - all this i/o stuff was easier under win98 - lol