Can't write plc variable qt

V0rtex

char  szVar[] = {"MAIN.PLCVar"};
AdsSyncReadWriteReq(pAddr, ADSIGRP_SYM_HNDBYNAME, 0x0, sizeof(lHdlVar), &lHdlVar, sizeof(szVar), szVar);
    //AdsSyncReadReq( pAddr, ADSIGRP_SYM_VALBYHND, lHdlVar, sizeof(nData), &nData );
    AdsSyncWriteReq(pAddr, ADSIGRP_SYM_VALBYHND, lHdlVar, sizeof(nData), &nData);
    AdsSyncWriteReq(pAddr, ADSIGRP_SYM_RELEASEHND, 0, sizeof(lHdlVar), &lHdlVar);
qDebug()<<nData;

when i do that this works fine but i want to make a function that write plc variable in function then set value what i want.

__declspec( dllexport )
long __stdcall AdsSyncReadWriteReq( AmsAddr* pAddr,					// Ams address of ADS server
							unsigned long indexGroup,			//	index group in ADS server interface
							unsigned long indexOffset,			// index offset in ADS server interface
							unsigned long cbReadLength,		// count of bytes to read
							void* pReadData,						// pointer to the client buffer
							unsigned long cbWriteLength, 		// count of bytes to write
							void* pWriteData						// pointer to the client buffer
							);

this is function

and when i want to do that this error is happening

ads.cpp:35:5: error: no matching function for call to 'AdsSyncReadWriteReq'
TcAdsAPI.h:67:16: note: candidate function not viable: no known conversion from 'char' to 'void *' for 7th argument; take the address of the argument with &

void ADS::ChangeValue(char varName)
{
    
    nData=80.1;
    AdsSyncReadWriteReq(pAddr, ADSIGRP_SYM_HNDBYNAME, 0x0, sizeof(lHdlVar), &lHdlVar, sizeof(varName), varName);
    //AdsSyncReadReq( pAddr, ADSIGRP_SYM_VALBYHND, lHdlVar, sizeof(nData), &nData );
    AdsSyncWriteReq(pAddr, ADSIGRP_SYM_VALBYHND, lHdlVar, sizeof(nData), &nData);
    AdsSyncWriteReq(pAddr, ADSIGRP_SYM_RELEASEHND, 0, sizeof(lHdlVar), &lHdlVar);
    qDebug()<<nData;
}

Christian Ehrlicher

And where's the relation to Qt? You call a simple C function but don't pass the correct type for the 7th argument. Fix it.

V0rtex

I know but may be you can help i tried and i cant

jsulm

@V0rtex What did you try to solve "no known conversion from 'char' to 'void *' for 7th argument"?

V0rtex

@jsulm yes i tried but i cant still. i didn't understand

SGaist

Hi,

@V0rtex said in Can't write plc variable qt:

@jsulm yes i tried but i cant still. i didn't understand

The question was: can you please explain what you tried that did not work ?