Re: DLT_request

[Guy Harris <guy () alum mit edu>]

On Jan 13, 2017, at 6:49 AM, Weber René <rweber () baumer com> wrote:

> On Jan 11, 2017, at 11:42 PM, Weber René <rweber () baumer com> wrote:
>
> > > We working at software for industrial cameras which are supported by the cameralink standard. We use Wireshark to 
> > > monitor the control interface. We have implemented a solution similar like the u3v dissector and uses link type 
> > > DLT_USER0.  The cameralink interface is basically a serial interface like rs232 uart.
>
> > So this is for GenCP over a serial port, rather than GenCP-over-UDP?
>
> I don't know a GenCP-over-UDP - where can I find some information about this?

OK, they mentioned UDP here:

        http://www.emva.org/wp-content/uploads/GenICam_GenCP_1.2.pdf

but they didn't really mention it as a transport.

> > So do the packets in such a pcap or pcapng file start with the serial prefix described in section 1.5 "Serial 
> > Prefix", followed by the common command data described in section 4.3 "Common Command Data", followed by the 
> > specific command data for the command in question (section 1.6 "Serial Postfix" says there's no postfix for serial 
> > ports)?
>
> correct. U3V in opposite to cameralink has a different prefix and a different endian order.

So the GenCP-over-serial endianness is big-endian, as per

        Appendix

        1. Serial Port Implementations

        This section specializes the generic protocol for the use over a serial link.

        1.1. Byteorder

        For devices communicating over a serial link the byte order of bootstrap registers and protocol fields is 
big-endian.
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