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Wireshark-dev: Re: [Wireshark-dev] rs485

From: Guy Harris <guy@xxxxxxxxxxxx>
Date: Tue, 28 Sep 2010 01:25:52 -0700
On Sep 28, 2010, at 12:56 AM, Agustin Figueredo Canosa wrote:

> I´m working with a link layer protocol using rs485 interface. I have
> created a dissector for my protocol and it works fine. But now I would
> like (if possible) to capture packets in real time.
> 
> I think it´s not possible to capture live data from rs485 using wireshark
> directly but if anyone have worked in it I'll be grateful for any help.

Ultimately, Wireshark's ability to capture from a traffic source is dependent on libpcap/WinPcap's ability to capture from it, which is dependent on the OS on which you're capturing and/or the hardware used for the capturing.  Modern versions of libpcap (for UN*X systems) and WinPcap (for Windows) support adding modules to handle various types of capture hardware and software (although they're modules compiled into the libpcap or WinPcap library, not plug-in modules loaded at run time).

On what operating system or operating systems do you want to do the capturing?  What software does it have to support RS-485?

What sort of hardware do you have to connect to the RS-485-based network?  An RS-485-to-USB converter, as you mention, or some other form of hardware (such as a serial transceiver)?

Do you want to capture traffic on an RS-485-based network that's neither sent to nor from the machine doing the capturing ("third-party" capture), or do you just want to capture traffic sent to or from your machine?