Adding custom ID String to Signal/Slot Event?

SeppyQT

Hallo,

I have a Problem with QModbusServer. I want to pass an custom Identification string for every ModbusServer Instance.

void QModbusManager::onServerAddClick()
{
	QModbusServer* device = new QModbusTcpServer(this);
	QModbusDataUnitMap reg;
	reg.insert(QModbusDataUnit::Coils, { QModbusDataUnit::Coils,0,20 });
	reg.insert(QModbusDataUnit::DiscreteInputs, { QModbusDataUnit::DiscreteInputs,0,20 });
	reg.insert(QModbusDataUnit::InputRegisters, { QModbusDataUnit::InputRegisters,0,20 });
	reg.insert(QModbusDataUnit::HoldingRegisters, { QModbusDataUnit::HoldingRegisters,0,20 });
	device->setMap(reg);
	auto name = this->ui.tb_servername->text();
	connect(device, &QModbusServer::dataWritten, this, [&](QModbusDataUnit::RegisterType type, int address, int size) { 
		this->DataWrittenCallback(name, type, address, size);
		});
	
	//connect(device, &QModbusServer::dataWritten, this, &QModbusManager::DataWrittenCallbacktest);
	connect(device, &QModbusServer::errorOccurred, this, [&](QModbusDevice::Error error) { this->ErrorCallback(name, error); });

	//Setting UP IP
	auto m = ui.lv_interfaces->currentIndex();
	auto ip = m.data(Qt::DisplayRole).toString();
	device->setServerAddress(1);
	device->setConnectionParameter(QModbusDevice::NetworkAddressParameter, ip);
	device->setConnectionParameter(QModbusDevice::NetworkPortParameter, this->ui.tb_port->text());
	QPair<QModbusServer*, QString> p(device, this->ui.tb_target->text());
	this->deviceMap.insert(name, p);
	device->connectDevice();
	this->setupTabPage(name);
}

When I click Add Server. It registers the Server Name and in the deviceMap there is the correct name. But when the Event is invoked name = ??? (Debugger Visual Studio 2019). Why does it forget the value?

My Intention is to add a Sender Information like in C# Winforms eventcallback(object sender, EventArgs e) or POCO C++ eventCallback(void* sender, EventArgs& arg)

mrjj

Hi
it seems
auto name = this->ui.tb_servername->text();
is a local variable and you seems to capture it by referene so when
onServerAddClick ends, its no longer valid. (and dataWritten fires much later)
Try
connect(device, &QModbusServer::dataWritten, this, [=]

SeppyQT

Thanks,

my bad, I misinterpreted the & inside the brackets. I thought [&] were for the lazies meaning include everything. Now I know it is = for values.

If you wonder why I need multiple Modbus Servers It shall be a Modbus to UDP JSON connector.

mrjj

@SeppyQT
np :)
I shot my foot of a few times capturing locals by reference.