getting results from controller via usb failes - c++

Question

Im trying to write a programm in c++ to let my computer communicate with a trinamic steprockerboard.
They already provided an example file, to get you on the way. This works perfect, but is really simplistic.
Now I want to read the results from the usb device, and they made a function for that:
//Read the result that is returned by the module
//Parameters: Handle: handle of the serial port, as returned by OpenRS232
//Address: pointer to variable to hold the reply address returned by the module
// Status: pointer to variable to hold the status returned by the module (100 means okay)
//Value: pointer to variable to hold the value returned by the module
prototype:
UCHAR GetResult(HANDLE Handle, UCHAR *Address, UCHAR *Status, int *Value)
Now I wrote the following:
UCHAR* adr;
UCHAR* stat;
int* val;
SendCmd(RS232Handle, 1, TMCL_MVP, 0, 0, -3200); // move to next position
SendCmd(RS232Handle,1, TMCL_GAP, 8, 0, 0); // tell motor to look if position is reached
GetResult(RS232Handle,adr,stat,val); //ask for the result, value must give a 1 if so
printf("results from USB device: adr=%d, stat=%d, val=%d\n", adr, stat, val);
But when I run the program, and try this option, the program chrashes.
Has anybody got an idea what might cause the problem? (the code I supplied is only a part of my program, the whole code can be find below.
It is not my intention that you read the whole code, the problem should be above, but only for who is interested I also put the rest down here)
// TMCLTest.cpp : Show how to communicate with a TMCM module in TMCL
//
#include "stdafx.h"
#include <iostream>
//Opcodes of all TMCL commands that can be used in direct mode
#define TMCL_ROR 1
#define TMCL_ROL 2
#define TMCL_MST 3
#define TMCL_MVP 4
#define TMCL_SAP 5
#define TMCL_GAP 6
#define TMCL_STAP 7
enter code here#define TMCL_RSAP 8
enter code here#define TMCL_SGP 9
#define TMCL_GGP 10
#define TMCL_STGP 11
#define TMCL_RSGP 12
#define TMCL_RFS 13
#define TMCL_SIO 14
#define TMCL_GIO 15
#define TMCL_SCO 30
#define TMCL_GCO 31
#define TMCL_CCO 32
//Opcodes of TMCL control functions (to be used to run or abort a TMCL program in the module)
#define TMCL_APPL_STOP 128
#define TMCL_APPL_RUN 129
#define TMCL_APPL_RESET 131
//Options for MVP commandds
#define MVP_ABS 0
#define MVP_REL 1
#define MVP_COORD 2
//Options for RFS command
#define RFS_START 0
#define RFS_STOP 1
#define RFS_STATUS 2
#define FALSE 0
#define TRUE 1
//Result codes for GetResult
#define TMCL_RESULT_OK 0
#define TMCL_RESULT_NOT_READY 1
#define TMCL_RESULT_CHECKSUM_ERROR 2
//Open serial interface
//Usage: ComHandle=OpenRS232("COM1", CBR_9600)
HANDLE OpenRS232(const char* ComName, DWORD BaudRate)
{
HANDLE ComHandle;
DCB CommDCB;
COMMTIMEOUTS CommTimeouts;
ComHandle=CreateFile(ComName, GENERIC_READ|GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
if(GetLastError()!=ERROR_SUCCESS) return INVALID_HANDLE_VALUE;
else
{
GetCommState(ComHandle, &CommDCB);
CommDCB.BaudRate=BaudRate;
CommDCB.Parity=NOPARITY;
CommDCB.StopBits=ONESTOPBIT;
CommDCB.ByteSize=8;
CommDCB.fBinary=1; //Binary Mode only
CommDCB.fParity=0;
CommDCB.fOutxCtsFlow=0;
CommDCB.fOutxDsrFlow=0;
CommDCB.fDtrControl=0;
CommDCB.fDsrSensitivity=0;
CommDCB.fTXContinueOnXoff=0;
CommDCB.fOutX=0;
CommDCB.fInX=0;
CommDCB.fErrorChar=0;
CommDCB.fNull=0;
CommDCB.fRtsControl=RTS_CONTROL_TOGGLE;
CommDCB.fAbortOnError=0;
SetCommState(ComHandle, &CommDCB);
//Set buffer size
SetupComm(ComHandle, 100, 100);
//Set up timeout values (very important, as otherwise the program will be very slow)
GetCommTimeouts(ComHandle, &CommTimeouts);
CommTimeouts.ReadIntervalTimeout=MAXDWORD;
CommTimeouts.ReadTotalTimeoutMultiplier=0;
CommTimeouts.ReadTotalTimeoutConstant=0;
SetCommTimeouts(ComHandle, &CommTimeouts);
return ComHandle;
}
}
//Close the serial port
//Usage: CloseRS232(ComHandle);
void CloseRS232(HANDLE Handle)
{
CloseHandle(Handle);
}
//Send a binary TMCL command
//e.g. SendCmd(ComHandle, 1, TMCL_MVP, MVP_ABS, 1, 50000); will be MVP ABS, 1, 50000 for module with address 1
//Parameters: Handle: Handle of the serial port (returned by OpenRS232).
// Address: address of the module (factory default is 1).
// Command: the TMCL command (see the constants at the begiining of this file)
// Type: the "Type" parameter of the TMCL command (set to 0 if unused)
// Motor: the motor number (set to 0 if unused)
// Value: the "Value" parameter (depending on the command, set to 0 if unused)
void SendCmd(HANDLE Handle, UCHAR Address, UCHAR Command, UCHAR Type, UCHAR Motor, INT Value)
{
UCHAR TxBuffer[9];
DWORD BytesWritten;
int i;
TxBuffer[0]=Address;
TxBuffer[1]=Command;
TxBuffer[2]=Type;
TxBuffer[3]=Motor;
TxBuffer[4]=Value >> 24;
TxBuffer[5]=Value >> 16;
TxBuffer[6]=Value >> 8;
TxBuffer[7]=Value & 0xff;
TxBuffer[8]=0;
for(i=0; i<8; i++)
TxBuffer[8]+=TxBuffer[i];
//Send the datagram
WriteFile(Handle, TxBuffer, 9, &BytesWritten, NULL);
}
//Read the result that is returned by the module
//Parameters: Handle: handle of the serial port, as returned by OpenRS232
// Address: pointer to variable to hold the reply address returned by the module
// Status: pointer to variable to hold the status returned by the module (100 means okay)
// Value: pointer to variable to hold the value returned by the module
//Return value: TMCL_RESULT_OK: result has been read without errors
// TMCL_RESULT_NOT_READY: not enough bytes read so far (try again)
// TMCL_RESULT_CHECKSUM_ERROR: checksum of reply packet wrong
UCHAR GetResult(HANDLE Handle, UCHAR *Address, UCHAR *Status, int *Value)
{
UCHAR RxBuffer[9], Checksum;
DWORD Errors, BytesRead;
COMSTAT ComStat;
int i;
//Check if enough bytes can be read
ClearCommError(Handle, &Errors, &ComStat);
if(ComStat.cbInQue>8)
{
//Receive
ReadFile(Handle, RxBuffer, 9, &BytesRead, NULL);
Checksum=0;
for(i=0; i<8; i++)
Checksum+=RxBuffer[i];
if(Checksum!=RxBuffer[8]) return TMCL_RESULT_CHECKSUM_ERROR;
*Address=RxBuffer[0];
*Status=RxBuffer[2];
*Value=(RxBuffer[4] << 24) | (RxBuffer[5] << 16) | (RxBuffer[6] << 8) | RxBuffer[7];
} else return TMCL_RESULT_NOT_READY;
return TMCL_RESULT_OK;
}
int main(int argc, char* argv[])
{
int i;
int Type, Motor, Velocity, Position,ref1;
UCHAR Address, Status;
int Value, Timeout;
HANDLE RS232Handle;
RS232Handle=OpenRS232("COM3", 9600);
// set parameters
SendCmd(RS232Handle, 1, TMCL_SAP, 140, 0, 5); //SAP 140, 0, 5 // set microsteps to 32 (32 additional steps per step of 1.8 degr.)
//SAP 4, 0, 500 //set max vel.
//SAP 5, 0, 100 //set max acc.
//SAP 6, 0, 255 //set abs. max current to 2.8 ampere
//SAP 7, 0, 50 //set standby current ((50/250)*2.8A)
printf("VPI Test Setup\n \n" );
do
{
printf("1 - Rotate clockwise (10 rotations)\n");
printf("2 - Rotate counter-clockwise (10 rotations)\n");
printf("3 - Stop motor\n");
printf("4 - Start test (First 100 rotations clockwise, \n then 100 rotations counter clockwise)\n");
printf("\n99 - End\n");
scanf("%d", &i);
switch(i)
{
case 1:
SendCmd(RS232Handle, 1, TMCL_MVP, 0, 0, 32000); //ABS(4th parameter) = 0
break;
case 2:
SendCmd(RS232Handle, 1, TMCL_MVP, 0, 0, -32000); //ABS(4th parameter) = 0
break;
case 3:
SendCmd(RS232Handle, 1, TMCL_MST, 0, 0, 0);
break;
case 4:
//SendCmd(RS232Handle, 1, TMCL_RFS,0,0,0);
printf("Test started \n" );
//UCHAR done;
UCHAR* adr;
UCHAR* stat;
int* val;
//SendCmd(RS232Handle, 1, TMCL_SAP, 193, 1, 2); //SAP 193,1,2
SendCmd(RS232Handle, 1, TMCL_MVP, 0, 0, -3200); //ABS(4th parameter) = 0
SendCmd(RS232Handle,1, TMCL_GAP, 8, 0, 0);
GetResult(RS232Handle,adr,stat,val);
printf("results from USB device: adr=%d, stat=%d, val=%d\n", adr, stat, val);
//CHAR GetResult(HANDLE Handle, UCHAR *Address, UCHAR *Status, int *Value)
// if(done != 2)
// {
// printf("rotation backwards started \n");
// SendCmd(RS232Handle, 1, TMCL_MVP, 0, 0, 3200);
// }
// }
break;
}
SendCmd(RS232Handle, 1, TMCL_ROL, 0, Motor, Velocity);
SendCmd(RS232Handle, 1, TMCL_ROL, 0, Motor, Velocity);
if(i==1 || i==2 || i==3 || i==4)
{
Address=0;
Status=0;
Value=0;
Timeout=GetTickCount();
while(GetResult(RS232Handle, &Address, &Status, &Value) ==TMCL_RESULT_NOT_READY && abs(GetTickCount()-Timeout)<1000);
printf("Result: Address=%d, Status=%d, Value=%d\n", Address, Status, Value);
}
}
while(i!=99);
CloseRS232(RS232Handle);
return 0;
}

Answer 1

Address, Status and Value should point to valid variables. So, your code should look something like:
UCHAR adr;
UCHAR stat;
int val;
GetResult(RS232Handle,&adr,&stat,&val);
What is happening now is that your variables (adr, stat and val) are not initialized, so, they point to random locations in memory. When you pass these variables to GetResult, it tries to write to those random locations.