MODBUS RTU over Serial Port for Freescale microprocessor

[LuisMontoya]

I'm trying to communicate with a Freesacle Microprocessor MKL15Z32VFM4.

The protocol is using the TTL-UART port of the processor and MODBUS RTU, 19200, 8 data bits, 1 startBit, 1 stop bit, parity Even.

I have some string instructions to processor as "STATUS" or "DCLEVEL", and CRC bytes, etc. and of course I have to read the return,

Do any body makes this one before on Labview? 

I review the most of the MODBUS RTU post (and still reviewing), but I can't find anything than works.

Thank you!

[PointOnePa]

Luis,

I downloaded the NI-Modbus library, V1.2.1 zip file and was able to get the RS232 serial RTU demo to work with a Panasonic GT01 touchscreen. I'm using LabVIEW 2011.  I just had to following the installation instructions, and then ran the "MB Modbus Demo Box Example.vi" within the NI Modbus.llb.  This demo acts as a slave.

http://www.ni.com/example/29756/en/

I'm customizing the demo for my application.  Once I get the slave application working, I plan to switch to a master so I can then replace the GT01 touchscreen with a PC for the purpose of automated testing.

I did have to customize the demo to get it to work. The demo doesn't pull out the baud rate as a control and defaults to 9600. I'm running at 38400, so I added a control for that purpose.

The difficulty with the RTU implementation is the 3.5 byte timing which typically will cause the baudrate generator to have a framing error. I've not dug into the details yet, but the library appears to address that issue.

[LuisMontoya]

Thank You PointOne, I'll cotinue trying..

[PointOnePa]

I had to dig a bit into the modbus LabVIEW library. I modified the source, but it lets you see the details of the packet.

Useful when debugging.  Just recompile it for the version of LabVIEW that you are using.

[Luis_CT]

Hello Luis,

Thanks for using the NI forums! Please review the following examples from the LabVIEW DSC module:

• Modbus Fundamentals.lvproj
• Modbus Simulator.lvproj

You can find those examples in LabVIEW --> Help --> Find Examples...

But you will need to have installed the LabVIEW DSC module. Ileaveyouaswellsomeusefullinksinwhichyoucanfindotherusefulexamplesandinformation:

http://www.ni.com/white-paper/7675/en/

http://forums.ni.com/t5/LabVIEW/Need-help-with-Modbus-RTU-over-TCP-communication/td-p/1681618

Hope this information works for you!

[LuisMontoya]

thank you all.

my project is working now.