Modbus Over UDP

[Sonti_11532]

Hello,

Is it possible to implement the Modbus Over UDP protocol in LabVIEW using Data logging and Supervisory Control (DSC) toolkit?

Regards,

S Nagaraju

[Tapan_Mojidra]

Hello Nagaraju,

Data logging and Supervisory Control (DSC) toolkit proivides only modbus over serial and tcp.

You have to develop your own low level vi's to implement modbus over udp. 

You can get more information about modbus over udp from the link below

http://jamod.sourceforge.net/development/udp_master_howto.html

http://jamod.sourceforge.net/development/udp_slave_howto.html

[Sonti_11532]

Hello Tapan_Mojidra,

Thank you very much for response.

Do you have any example VIs for Modbus Over UDP?

Regards,

S Nagaraju.

[kartiknattar]

Hello Nagaraju,

Unlike Modbus/TCP, Modbus/UDP is not covered by a standard. That means there is no standards document which covers how it works and you will need to verify the vendor's implementation. However, here is something which explains it:

http://jamod.sourceforge.net/kbase/modbus_udp.html

I can't of course guaranty that this is how your I/O works.

[pincpanter]

In my understanding, UDP Modbus is almost the same as TCP Modbus, so I would download the old free NI Modbus library at

ftp.ni.com/pub/devzone/epd/nimodbus121.zip

It has been superseded by another library, but in fact it worked well in my applications; furthermore, you are able to manipulate the code.

It's "enough"  to replace the TCP part of the code with the corresponding UDP functions.

It should not be an impossible task.

[drugo]

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@pincpanter  ha scritto:

....

It should not be an impossible task.

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Hi, I'm sorry, but it did not work for me.

Did anyone actually develope a modbus over udp driver?

Thanks,

Andrea