I have a couple of questions to understand your use case better.
> -----Original Message-----
> From: Interest [mailto:interest-bounces+alexander.blasche=qt.io@qt-
> project.org] On Behalf Of Pfeiffer, Stephan
....
> void BModbus::requestRequiredSlot(BModbusData *data)
>
> {
>
> QModbusDataUnit du(QModbusDataUnit::HoldingRegisters, data->address(),
> data->datatype().second);
>
> QModbusReply *reply = c->sendReadRequest(du,255);
>
> connect(reply,&QModbusReply::finished,this,&BModbus::readyReadSlot);
>
> }
>
> Everything is working fine if I poll one Modbus address.
> The Wireshark Protocol says that only one query is placed in one TCP-package.
>
> If I query more than one modbus address, then there are all modbus queries in
> one TCP-package (also logged with Wireshark). And my device only sends an
> answer to the last ID in the package.
I take it that you repeat the sendReadRequest() call above multiple times in
quick succession (almost like in a loop)?
When you talk about ID, are you talking about the server address (255 above) or
are you talking about different holding register addresses (data->address()
above) on the same server address?
> Can anyone help me so that the QModbusTcpClient packs every Modbus ID into
> a seperate TCP-package instead of all in one?
Once I have an answer I might be able to help. There is two more hints which I
can give you which might help to debug the problem:
1.) You can enable more detailed logging output by adding
QLoggingCategory::setFilterRules(QStringLiteral("qt.modbus* = true"));
As first line to your main() function.
2.) The relevant code for your use case is in qmodbustcpclient_p.h.
enqueueRequest() is the function that ultimately creates the ADU/PDU. There you
can see the relevant logging output.
--
Alex
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