I need to read the current status of a com port. I seem to remember seeing it in the manual once, but I can't find it now. I'm sure it's possible. Can anyone help me?

Duane Pekse, Developer

Aldata Software

I don't know if the following code is of use.

We use it to communicate with a digitiser tablet.

There are many other procedures also, but this one may have what you need.

Sorry about the wrapping, Revtech should make the edit box resizable.

COMPILE SUBROUTINE COMM_ACCESS(MODE,COMM_PORT_HANDLE,COMMDATA)

* STANDARD

* Open/Close Comm port, Read/Write to port

* AG - May 96

*

DECLARE FUNCTION BLANK_STRUCT,GET_PROPERTY,STRUCT_TO_VAR,VAR_TO_STRUCT

DECLARE FUNCTION OpenComm,CloseComm,BuildCommDCB,SetCommState,ReadComm,WriteComm

BEGIN CASE

	CASE MODE=OPEN"	;GOSUB OPEN_PORT

	CASE MODE=CLOSE"	;GOSUB CLOSE_PORT

	CASE MODE=READ"	;GOSUB READ_FROM_PORT

	CASE MODE=WRITE"	;GOSUB WRITE_TO_PORT

END CASE

RETURN

OPEN_PORT:

COMM_ERRORS="

COMM_ERRORS=-1 ;COMM_ERRORS=Invalid or unsupported device"

COMM_ERRORS=-2 ;COMM_ERRORS=Device already in use"

COMM_ERRORS=-10;COMM_ERRORS=Device already in use"

COMM_ERRORS=-12;COMM_ERRORS=Device baud rate is invalid"

*

PORT	 =COMMDATA

BAUD_RATE=COMMDATA

DATA_BITS=COMMDATA

STOP_BITS=COMMDATA

PARITY	 =COMMDATA1,1

FLOW_CONTROL=COMMDATA1,1

PORT_SETTINGS=PORT:":":BAUD_RATE:",":PARITY:",":DATA_BITS:",":STOP_BITS:\00\

PORT=PORT:\00\

INQSIZE=1024;OUTQSIZE=128

COMM_PORT_HANDLE=OpenComm(PORT,INQSIZE,OUTQSIZE)

LOCATE COMM_PORT_HANDLE IN COMM_ERRORS USING @VM SETTING POS THEN

	COMM_PORT_HANDLE=COMM_ERRORS

	RETURN

END

*

DCB_STRUCT=BLANK_STRUCT("DCB")

RETVAL=BuildCommDCB(PORT_SETTINGS,DCB_STRUCT)

COMM_PARAMS=STRUCT_TO_VAR(DCB_STRUCT,"DCB")

BEGIN CASE

	CASE FLOW_CONTROL=X"

		COMM_PARAMS=3

	CASE FLOW_CONTROL=H"

		COMM_PARAMS=5

		COMM_PARAMS=9

		COMM_PARAMS=64

END CASE

DCB_STRUCT=VAR_TO_STRUCT(COMM_PARAMS,"DCB")

RETVAL=SetCommState(DCB_STRUCT)

RETURN

CLOSE_PORT:

RETVAL=CloseComm(COMM_PORT_HANDLE)

RETURN

READ_FROM_PORT:

BUFF_LEN=50

COMMDATA=STR(\00\,BUFF_LEN)

RETVAL=ReadComm(COMM_PORT_HANDLE,COMMDATA,BUFF_LEN)

COMMDATA=FIELD(COMMDATA,\00\,1)

RETURN

WRITE_TO_PORT:

COMMDATA=COMMDATA:\00\

BUFF_LEN=LEN(COMMDATA)	

RETVAL=WriteComm(COMM_PORT_HANDLE,COMMDATA,BUFF_LEN)

RETURN

Thanks for the help. I have just one more question for you. Where did you find the OpenComm, CloseComm, etc Functions? Are they from a DLL, or are they part of OI? I couldn't find anything on them in the help file for OI, so I don't even have the prototype information.

Thanks again.

Duane

Aldata Software

Sorry, forgot this.

It is a link to a DLL, all a bit tricky though.

I get my programmers to do this for me.

Hope this helps

Code below:

USER

*

* CSSP Functions Below

*

SHORT PASCAL OpenComm(LPCHAR,USHORT,USHORT)

SHORT PASCAL CloseComm(SHORT)

USHORT PASCAL EnableCommNotification(SHORT,USHORT,SHORT,SHORT)

SHORT PASCAL BuildCommDCB(LPCHAR,LPCHAR)

SHORT PASCAL GetCommState(SHORT,LPCHAR)

SHORT PASCAL SetCommState(LPCHAR)

SHORT PASCAL ReadComm(SHORT,LPCHAR,SHORT)

SHORT PASCAL WriteComm(SHORT,LPCHAR,SHORT)

Thanks a million for the info.

I think I've got it now.

         Duane

Colin,

Mike Hyslop here. I'm one of Duane Pekse's co-workers. A couple of months ago, you and he conducted an exchange of information concerning using OI to read and write to a com port.

The project has since fallen into my hands. I have been attempting to use the code segment you sent Duane, but I am missing a key element. I need to see what an actual call to the COMM_ACCESS subroutine looks like.

Specifically, what the COMMDATA argument looks like. Would yo be so kind as to send an example of a call to this subroutine, with the arguments included.

Thanks, in advance.

Best Regards,

Mike Hyslop, P.Eng.

Aldata Software Mgt. Inc.

email:[email protected]

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