Re: Serial protocol questions

[ben@xxxxxxxxxxx]

You make several compelling points. I do agree it might be best to
have a polling environment.

I do also think that all HA items should share a similar protocol
schema. That was the precipitous of my question.

Its sound like the RS485 network should have one standard protocol,
possibly similar to that of xpl, and then interface via a host PC to
xpl.

So then, what protocol would work best? Is there a dominant one to
consider in the HA market?


--- In ukha_xpl@xxxxxxx, "Neil Wrightson" <neilw@n...>
wrote:
> Hi All,
>
> I have done a lot of comms work in the past, both RS232 and RS485.
> RS485 really has to be a polled environment I.e. a master with
polled
> slaves. I'm only just starting to look at Xpl at this stage and it
appears
> that the heartbeat is a rather critical aspect to this protocol.
> I believe that the RS485 master should be aware of all of it's
slaves and
> that the master sends a heartbeat to it's master xXPLHAL??) for
its self and
> each of its slaves.
> Perhaps xPLHAL should advise the master 485 device what slaves it
should be
> talking to and what there functionality is.
>
> To me part of the question is, should the RS485 network try to
emulate xPL
> or as suggested just use a proprietary protocol. I already have
proprietary
> protocols in place so this would be easier.
> But,
> In my house I do not want to have multiple RS485 networks with
separate
> proprietary protocols. I will probably end up making most of my own
> hardware, but who knows I may wish to buy somebody else's 485
hardware item
> I.e. RFID and connect it onto my network. This wont work if we all
have
> separate 485 protocols.
>
> I think one of the early on questions is, What is the master? Is
it part of
> xPLHAL I.e. a PC is the master or should there be a separate
standalone
> master that talks to HAL via another serial connection. If XPLHAL
is the
> master we need somebody that can handle the 485 comms on the PC
I.e. Rx,Tx
> and a handshake line.
>
> By the way, I have already interfaced to RFID devices. Most
commercially
> available RFID devices talk to other equipment via a 26bit weigand
> interface.
>
> Regards,
>
> Neil Wrightson.
> -----Original Message-----
> From: Frank Mc Alinden [mailto:fmcalind@b...]
> Sent: Sunday, 23 January 2005 8:08 AM
> To: ukha_xpl@xxxxxxx
> Subject: Re: [ukha_xpl] Serial protocol questions
>
>
>
> Hi Ben
>
>         No one that im aware of has done any xPL stuff using rs485
and i
> have been pondering over the same questions that you are currently
asking,
> as i have some rfid readers and i intend to have a little xPL rs485
> network......
>
> > 1) Should I be implementing xpl on this device via serial?
>
> Can be done ok , but each device must generate hbeats and on a
rs485 network
> ,multiple devices could send hbeats at the same time ..???
>
> > 2) What schema(s) should I be using?
>
> I would assume the control.basic..Sensor.basic could be used here
>
> > 3) Would it be better to create a proprietary protocol and have
> > someone write a plug-in interface to xpl?
>
> Yes this is another option and i have done this with my Probe
system....
> You still have the issue of devices sending data at the same time
therefore
> getting corrupted messages unless the app polls each device on the
network
> ...???
>
> > 4) What resources are available to use as a reference beside the
xpl
> > official website.
>
> No rs485 resources that im aware of ....
>
> Frank
>
>
>
> ----- Original Message -----
> From: <ben@b...>
> To: <ukha_xpl@xxxxxxx>
> Sent: Sunday, January 23, 2005 6:24 AM
> Subject: [ukha_xpl] Serial protocol questions
>
>
> >
> >
> > I am in the midst of a project and was thinking about making the
> > device xpl compatible.
> > The device is a magnetic card reader (credit card) with and
onboard
> > relay to open an electrical door lock. The idea is you would
swipe a
> > credit card this device sends the account number to a host
computer
> > (via RS-485). The host determines if the account is allowed
access
> > and opens or denies access appropriately.
> > This device is run by a pic microprocessor.
> >
> > Questions:
> >
> > 1) Should I be implementing xpl on this device via serial?
> > 2) What schema(s) should I be using?
> > 3) Would it be better to create a proprietary protocol and have
> > someone write a plug-in interface to xpl?
> > 4) What resources are available to use as a reference beside the
xpl
> > official website.
> >
> > Thanks!
> >
> >
> >
> >
> >
> >
> > xPL Links: http://www.xplproject.org.uk
<http://www.xplproject.org.uk>
> http://www.xplhal.com <http://www.xplhal.com>
> http://www.xpl.myby.co.uk
<http://www.xpl.myby.co.uk>
> > To Post a Message: ukha_xpl@xxxxxxx
> > To Subscribe:  ukha_xpl-subscribe@xxxxxxx
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> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
>
>
>
> xPL Links: http://www.xplproject.org.uk
<http://www.xplproject.org.uk>
> http://www.xplhal.com <http://www.xplhal.com>
http://www.xpl.myby.co.uk
> <http://www.xpl.myby.co.uk>
> To Post a Message: ukha_xpl@xxxxxxx
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>
>
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