How to pass binary values to mex

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A R 2020-3-3

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评论： A R 2020-3-5

Hello, I want to transmit 1x12 binary data to mex file for data transmission

b=70.19
Y = round(b,1);
dec= Y*10;
integers=dec;
temp = integers;
mask = temp < 0;
temp(mask) = 2^12 + temp(mask) ;
a=decimalToBinaryVector(temp, 12);

The output binary values (a) is : 0 0 1 0 1 0 1 1 1 1 1 0

When I pass these values to mex file,

b= mex(a);

I get a different binary value. The output of a is:

1.18870000000000e-320 1.18870000000000e-320 1.00000000000053 1.18870000000000e-320 1.00000000000053 1.18870000000000e-320 1.00000000000053 1.00000000000053 1.00000000000053 1.00000000000053 1.00000000000053 1.18870000000000e-320

mex.c

void mexFunction( int nlhs, mxArray *plhs[],
                  int nrhs, const mxArray *prhs[] )
{
   double *a;
  int M,N;
  double* bb;  /* 1xN output  matrix */  
  const mwSize *dims;
  a=mxGetData(prhs[0]);
  plhs[0] =  mxCreateDoubleMatrix(M, N, mxREAL);
  bb = mxGetPr(plhs[0]);
  analogoutputMatlab(a,bb,N);
  }

Why do I get change in binary values? How to pass binary values to mex?

14 个评论
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A R 2020-3-4

编辑：A R 2020-3-4

在 MATLAB Online 中打开

Hello Walter, The decimalToBinaryVector function gives 1x12 double.

bb= mexfile(a);

I am passing the binary value 'a' to a mex file. I transmit the binary value to analog output pin. After that I am getting the transmitted binary value in the analog input pin and reading it in MATLAB . So In the code above 'bb' is the received binary value from DAQ.

b=70.19
Y = round(b,1);
dec= Y*10;
integers=dec;
temp = integers;
mask = temp < 0;
temp(mask) = 2^12 + temp(mask) ;
a=decimalToBinaryVector(temp, 12);   %it gives 1x12 double
The output binary values (a) is :  0	  0	1	0	1	0	1	1	1	1	1	0

The above code gives the correct binary value. But when I pass these value to my mex file like below code, the output of binary value (a) gets changed.

b=70.19
Y = round(b,1);
dec= Y*10;
integers=dec;
temp = integers;
mask = temp < 0;
temp(mask) = 2^12 + temp(mask) ;
a=decimalToBinaryVector(temp, 12);
bb= mexfile(a);

I get a different binary value. The output of a is:

Why my binary value ( a=decimalToBinaryVector(temp, 12);) is getting changed when I call mex file? I only call my mex file after getting the binary values. So how calling my mex file alters the output of my binary values?

A R 2020-3-4

在 MATLAB Online 中打开

James, I think I didnt get your questions correctly. cbAOut( ) and cbAIn( ) are inbuilt functions from universal library.

    int		BoardNum = 0;
    int		ULStat = NOERRORS;
    int		Chan, NumAIChans;
    int		Range = BIP5VOLTS;
    int		Options = FOREGROUND;
    int		ChannelType = ANALOGINPUT;
   char	        BoardName[BOARDNAMELEN];
   int		ch1 = 0;
        int		Chan1, ExitFlag;
        int		NumAOChans;
	int		ChannelType1 = ANALOGOUTPUT;
	int		i;
ULStat = cbAOut(BoardNum, Chan1, Range, data[i]);

I have mentioned the data types of the variables used in cbAOut().

I can attach the example analog output C program from universal library.

/*ULAO01.C****************************************************************
File:                         ULAO01.C
Library Call Demonstrated:    cbAOut()
Purpose:                      Writes to a D/A Output Channel.
Demonstration:                Sends values to D/A 0.
Other Library Calls:          cbErrHandling()
                              cbFromEngUnits()
Special Requirements:         Board 0 must have a D/A output port.
Copyright (c) 1995-2020, Measurement Computing Corp.
All Rights Reserved.
***************************************************************************/
/* Include files */
#include "..\cbw.h"
#include "Utilities.h"
 int main(void)
{
	/* Variable Declarations */
	int		ch = 0;
    int		Row, Col;
    int		BoardNum = 0;
    int		ULStat = NOERRORS;
    int		Range = BIP5VOLTS;
    int		Chan, ExitFlag;
	int		NumAOChans, dummy;
	WORD	DataValue;
    float	EngUnits, voltsSent;
    float   RevLevel = (float)CURRENTREVNUM;
	int		DefaultTrig = TRIG_POS_EDGE;
	int		ChannelType = ANALOGOUTPUT;
	char	rangeName[RANGENAMELEN];
	double	rangeVolts, fullScalePlus, fullScaleMinus;
	char	BoardName[BOARDNAMELEN];
	/* Declare UL Revision Level */
	ULStat = cbDeclareRevision(&RevLevel);
	// get the name of the board
	if (!GetNameOfBoard(BoardNum, BoardName)) {
		DisplayMessage(NOERRORS);
		return 0;
	}
	/* set up the display screen */
	ClearScreen();
	printf("Demonstration of cbAOut() using %s.\n\n", BoardName);
	// Determine if device is compatible with this example
	NumAOChans = FindAnalogChansOfType(BoardNum, ChannelType, &ADRes, &Range, &Chan, &DefaultTrig);
	if (NumAOChans == 0) {
		printf("%s (board %u) does not have analog output channels.\n", BoardName, BoardNum);
		DisplayMessage(NOERRORS);
		return 0;
	}
	GetRangeInfo(Range, rangeName, &rangeVolts);
	fullScalePlus = rangeVolts;
	fullScaleMinus = 0;
	if(Range < 99) {
		fullScalePlus = rangeVolts / 2;
		fullScaleMinus = fullScalePlus * -1;
	}
	GetTextCursor(&Col, &Row);
    ExitFlag = FALSE;
	Chan = 0;
	printf("Current output range is %s.\n\n", rangeName);
	while (!ExitFlag) {
		MoveCursor(0, 2);
		printf("Enter a voltage between %.3f and %.3f: ", fullScaleMinus, fullScalePlus);
		MoveCursor(44, 2);
		dummy = scanf("%f", &EngUnits);
		ULStat = cbFromEngUnits(BoardNum, Range, EngUnits, &DataValue);
		ULStat = cbAOut(BoardNum, Chan, Range, DataValue);
		if (ULStat != NOERRORS) {
			DisplayMessage(ULStat);
			return 0;
		}
		ClearScreen();
		voltsSent = EngUnits;
		if (EngUnits > fullScalePlus) voltsSent = (float)fullScalePlus;
		if (EngUnits < fullScaleMinus) voltsSent = (float)fullScaleMinus;
		printf("\n  %.3f volts has been sent to D/A 0.\n\n", voltsSent);
		printf("Press Q to quit , any other key to continue:\n ");
		while (!_kbhit()) {}
		ch = _getch();
		if (ch == 'q' || ch == 'Q')
			ExitFlag = TRUE;
		ClearScreen();
	}
	DisplayMessage(NOERRORS);
	return 0;
}

Walter Roberson 2020-3-5

To be honest, I am not enthusiastic about rebooting my computer into Windows, doing hours and hours of Windows updates, downloading the Measurement Computing development library, installing a compiler, putting together the pieces of what you posted to try to produce a project, and figuring out how to use a Windows debugger.

James would probably appreciate if you put together a zip of everything together and a link of the Measurement Computing development package.

My personal suspicion is that you could perhaps produce a smaller example that did not call upon the measurement computing routines. And if you were to find that the trimmed example does not produce the same problem, then you would have isolated down to an interaction with MC libraries, which would give you information about what to look for.

A R 2020-3-5