Infinite update data over modbus protocol

UlrichRekkenin

Good day,

I`m trying to implement my ModbusWorker class:

class ModbusWorker : public QObject {

    Q_OBJECT

  public:
    explicit ModbusWorker(const QString &filename, QModbusClient* modbus = nullptr, QObject* parent = nullptr);
  private slots:
    void read();
    void readReady();
private:
    QTimer* _timer;
    Tags* _tags;
//...
}

where Tags is a class wich parses xml-file with modbus tags.
In the constructor QTimer connect with read():

 _timer = new QTimer();
  connect(_timer, &QTimer::timeout, this, &ModbusWorker::read);

And

void ModbusWorker::read(){
  QMapIterator<QString, Tag*> iterator(_tags->container(QModbusDataUnit::DiscreteInputs));
   while(iterator.hasNext()) {
       iterator.next();
       // construct QModbusDataUnit = data
       if (auto* reply = _modbusDevice->sendReadRequest(data, _server)) {
         if (!reply->isFinished()) {
           connect(reply, &QModbusReply::finished, this, &ModbusWorker::readReady);
         }
         else {
           delete reply;
         }
       }
     }
}

void ModbusWorker::readReady(){
  //..
  auto reply = qobject_cast<QModbusReply*>(sender());
  switch (reply->error()) {
    case QModbusDevice::NoError:
    // ...
      qInfo() << "type:" << unit.registerType() << "values =" << values;

    // another cases...
    default:
      qDebug() << "read response error:" << reply->error() << reply->errorString();
  }
}

Here is ther following response:
"read response error: QModbusDevice::Error(TimeoutError) 'Request timeout.'"

My question is how to manage infinitly process of updating data (read and write so on).

PS.
Tags in the xml-file may be unordered, so it`s impossible to use

_modbusDevice->sendReadRequest(QmodbusDataUnit(QModbusDataUnit::DiscreteInputs, startAddress, maxValues), _server);

I think this will not solve my problem, because there will be the sets[type][numberOfSet] of data for
each QModbusDataUnit::RegisterType type.

Upd.
The few first requests are done well with correct data, but shortly I get the error above.

SGaist

Hi and welcome to devnet,

I haven't used that module yet but are you sure you are not spamming your devices or triggering network congestion ?

From what you describe it sounds rather like you should trigger a read and once all your devices have been read restart the process rather than having a timer that doesn't take into account network and device(s) latencies.

UlrichRekkenin

@SGaist said in Infinite update data over modbus protocol:

I haven't used that module yet but are you sure you are not spamming your devices or triggering network congestion ?

Hi, I'm thinking that I do...