Modbus Sniffer

[TenJigoku77]

Hello guys,

I currently working with Modbus protocol and I need a modbus sniffer.
I have 2 systems communicating with each other using modbus RTU (half-duplex) and I need a library that decode the serial frames I'm getting.
Modbus has a lot of function and exception code so coding it manually would take me a lot of time.
I guess I'm not the 1st one to work with something like that, do you have in mind any library or something like that, that could help me ?
Thanks and see you soon I hope 😉

[cyongjed]

Hi Ten,

You can use the native Modbus Library API which can be downloaded from VI Package Manager when interfacing with LabVIEW.

Hope this helps.

[K C]

Hi,

When I have the ModBus communication running I don't need a sniffer anymore. Even if you get exceptions. Because receiving an exception means that the (basic) communication is Ok.

You know what you are sending to the slave. If you get an exception I think the manual of the slave (RTFM) would be of more help than a sniffer.

Kees

[TenJigoku77 · Accepted solution]

Hey.
In fact I'm validating communication between 2 products and I need to spy the communication.
In fact I just developped an algorythm to separate the request from the response and then I parse the frames.
The separation is not easy because no start or stop bit with modbus rtu.
So I determined that I can't have 2 requets in a row and when I get a request, I parse the frame and I wait for the next one, wich will be a response, and so on.
Thanks for your response anyway, problem solved.