QByteArray::operator QNoImplicitBoolCast() const' is private

[saman_artorious]

void rs485::rs485DataAquisition(QByteArray data)   //0-SubSystem---------1-Pid--------2-Value
{
    QByteArray receivedData;
    unsigned char address;
 
    qDebug() << "rs485DataAquisition()" << data.toHex();
 
    if(data.toHex() < "0x06")
 
    if( data.toHex() < _ENGINEROOM_SUBS )
    {//Engine Compartment Elements
 
        qDebug() << "Engine Compartment Elements";
 
        if(data.size() == 1)
        {
            qDebug() << "Reading request..";
 
            if(rs485WriteData(_READ_ENGINEADDRESS, data.toHex()))       // I get the error here, the second parameter of this function is unsigned char
            {
                rs485Delay();
 
                qDebug() << "NOW -> rs485CheckAck()";

void rs485::rs485DataAquisition(QByteArray data)   //0-SubSystem---------1-Pid--------2-Value
{
    QByteArray receivedData;
    unsigned char address;

    qDebug() << "rs485DataAquisition()" << data.toHex();

    if(data.toHex() < "0x06")

    if( data.toHex() < _ENGINEROOM_SUBS )
    {//Engine Compartment Elements

        qDebug() << "Engine Compartment Elements";

        if(data.size() == 1)
        {
            qDebug() << "Reading request..";

            if(rs485WriteData(_READ_ENGINEADDRESS, data.toHex()))       // I get the error here, the second parameter of this function is unsigned char
            {
                rs485Delay();

                qDebug() << "NOW -> rs485CheckAck()";

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[ChrisW67]

The second parameter you are passing to that function is not unsigned char, it is a QByteArray. Further, the byte array you are using is a string representation of the bytes in the array in hex: a very different thing to the actual bytes that you almost certainly want to be sending. The first byte in the QByteArray is an unsigned char:

if(rs485WriteData(_READ_ENGINEADDRESS, data.at(0)))

if(rs485WriteData(_READ_ENGINEADDRESS, data.at(0)))

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It seems you are generally confused about the difference between the value in a byte and the string representation of it. If you want to compare the value of the first byte in the QByteArray then do so directly, don't convert to a string and then compare. So, line 8 becomes:

if (data.at(0) < 0x06)  // notice no quotes and no toHex(), or
if (data.at(0) < 6)       // same thing in decimal

if (data.at(0) < 0x06)  // notice no quotes and no toHex(), or
if (data.at(0) < 6)       // same thing in decimal

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and line 10:

if( data.toHex() < _ENGINEROOM_SUBS )

if( data.toHex() < _ENGINEROOM_SUBS )

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I am assuming that _READ_ENGINEADDRESS and _ENGINEROOM_SUBS are defined integer literals in hex like

#define _READ_ENGINEADDRESS 0x06

#define _READ_ENGINEADDRESS 0x06

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which lead to think you needed to convert your byte array to a hex string.

[ChrisW67]

Just noticed a glitch in my last post. Line 10 should be something like:

if( data.at(0) < _ENGINEROOM_SUBS )

if( data.at(0) < _ENGINEROOM_SUBS )

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where you select the appropriate byte from the array to compare.