Messages in this thread | | | Subject | Re: Q: network driver with new protocol | Date | Tue, 11 May 1999 12:37:26 +0100 | From | David Woodhouse <> |
| |
schuldei@andrive.de said: > I have my field-bus-card (mcat/bitbus) up and running (as far as > hardware-configuration and detection is concerned) and want to > implement the fieldbus-protocol now.
> Of cause I want to use the kernel's infrastructure for queueing of > packages and stuff. But for the ease of coding I want to have the > protocol implemented in a library in user-space. I want the > kernel-driver to just receive and transmit the packages. How can I > implement the hooks for passing the packages up to user-land and > process them further?
> Untill now I used the ethernet setup stuff. But since my card uses > (kind of) RS485-serial protocol I will have to change that, too.
I'm also intending to at some point to implement a fieldbus protocol (Profibus) that runs over RS485. If we can design a simple way for user-space libraries to send and receive whole packets over RS485 media, then it could be used by many such projects.
I was intending to do it as a line discipline, although the 'normal' line discipline behaviour isn't good enough for synchronous operation. However, the N_HDLC line discipline which turned up in 2.2.x recently may well prove to be an extremely good model for what we want.
Basically, the Profibus definition of a 'packet' is a sequence of bits which is preceded and followed by 33 idle bits (3 characters @ _8n1_). That's about the only information that needs to be passed down to that layer - the amount of time to leave as a 'packet gap'. What about your system?
What hardware are you using for RS485 communication? I'm looking at the Comtrol RocketPort 485 cards, but haven't yet been approved to actually go ahead and spend real money on the project.
<PLUG> For people interested in Profibus on Linux, we already have some intelligent IO cards from Applicom (www.applicom-int.com) working under Linux in a production environment. Let me know if you want more information. </PLUG>
---- ---- ---- David Woodhouse David.Woodhouse@mvhi.com Office: (+44) 1223 810302 Project Leader, Process Information Systems Mobile: (+44) 976 658355 Axiom (Cambridge) Ltd., Swaffham Bulbeck, Cambridge, CB5 0NA, UK. finger dwmw2@ferret.lmh.ox.ac.uk for PGP key.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |