Modbus, QextSerialPort and QTimer

[^NyAw^]

Hi,

I've found what is happening.
Taking a look at Modbus Master protocol I found that Master can only send one request at a time. So, if I send a request and another request before the Slave device sends a response, the Slave device don't know what is happening.

So, what I'm gona do is to make CModbusRTUMaster as a QThread with a QMutex. Doing this I will block the CModbusRTUMaster to send another request until a response is arrived(timeout).

Any ideas would be well recived, and if someone have developed the Modbus protocol in Qt it will be wonderfull to take a look at it. Maybe if my classes work well I will let you download to test and modify them to make them better(first of all I will have to translate it from spanish to english).

Thanks,

[ericklg]

Hi Oscar, i am trying to develop Mobus with Qextserialport too and i am starting now, i would like to help you developing your clases, i speak spanish, if you are interest you can email me to gmail, my user is erick.lglez
I hope we can help ich other.
Si puedes mandame lo que has hecho es para no comenzar desde zero...
Muchas gracias de antemano
Erick

[photovoltaico]

Dear Nyaw,
about serial modbus comunication, I must to develop a simple program, similar ad datalogger, that every xx second send a request to slave, and capture response.

I'm newbie from C++ and Qt, so what are the first steps to write this application?

For example:
1. create serial connection (what are the classes about that, or there is a documentation for that)
2. send request to modbus format (modbus frame)
3. read request and save data readed.
4. is necessary to use thread or is more efficiently insert the applicatin as crontab.

So, about modbus-serial connection - datalogging what are classes about?
Where I can found manual about that.
Or did you have some similar example from which I can view what is the procedure to create that application?

All advice ore source code example will be appreciate!

[cia.michele]

Dear NyAw
I'm a newbie of c++ and qt, and I need to create a modbus (rtu) communication and rs422 communication by serial and qt. I've seen the qextserialport library and i've tryed to run the example and activate an rs232 comunication successfully.

Now can you give me some giude-lines or example to realize modbus rtu protocol and rs422 comunication?

Thanks for your reply

Michele

[^NyAw^]

Hi,

As I said, I can't share the libs because there is code that is not Modbus related mixed in the classes. Also it is full programmed in Catalan(language from Catalonia, a region of Spain). And finally, I have no time to rewrite them as many people wants.

Take a look at:
http://www.modbus.org/specs.php
Here you can download the Modbus RTU and TCP specification.

Also download and take a look at "jamod" source code. It is a JAVA Modbus implementation that I have used to develop my own classes.
http://jamod.sourceforge.net/

Hope this help you