Modbus RTU interfacing with 8051

[Briez]

Help Required,

I want to make interfacing of Modbus RTU to the 8051 via rs232. I am new to this project, so please anyone help me.....
I have made serial communication hardware and simple code for communication of 8051 to PC hyper-terminal. Now i want to make C code for 8051 to communicate with MODBUS RTU protocol...... Can anyone please help me to write code...

Thanks In Advance...

 

[internetuser2k12]

Which compiler are you using?

 

[Briez]

I am Using MicroVision Keil V3......... For 8051

 

[FvM]

I guess, you'll want to read the documents Modbus_Application_Protocol and Modbus_over_serial_line from modbus.org.

Needless to say that there are tons of MODBUS example codes on the internet. But it might be reasonable to write your own code from the scratch. It's easy and will give you a better understanding.

 

[internetuser2k12]

Have you checked this link http://en.pudn.com/downloads127/sourcecode/embed/detail536781_en.html
http://www.omega.com/manuals/manualpdf/M3758.pdf
http://www.codeforge.com/article/28562
http://en.pudn.com/downloads151/sourcecode/embed/detail654304_en.html

 

[jignesh doshi]

tell me ur actual requirement...

 

[Briez]

->I want to interface Microcontroller 8051 with AC drive via RS-485 Protocol. And i didn't get reply when i am sending request to Drive.. I had made a Packet frame used to request to get response from drive.....

->I want to show only decimal data Stored in Holding Register of Drive on my 16x2 LCD attached to 8051.

-> Please help me . .

 

[FvM]

And i didn't get reply when i am sending request to Drive

There are many possible reasons. I suggest to check your MODBUS packet against a test tool, e.g. ModbusView

I want to show only decimal data Stored in Holding Register of Drive on my 16x2 LCD attached to 8051

The problem isn't particularly related to MODBUS, I think.

 

[Briez]

Hello FvM,
Right now i am using simply modbus 7.0, and i am making request frame as made by it.. totally right but still response didn't come... !!

 

[FvM]

Either your PC MODBUS interface is wrong or you misunderstand the required MODBUS setup of your drive (address, supported register numbers, baud rate, framing, bus wiring).

 

[jignesh doshi]

totally right but still response didn't come... !!

sorry for late reply...
tell me ur detail what u want to do..

and attach circuitdiagram also..