RE: Re: Serial protocol questions

["Neil Wrightson" <neilw@xxxxxxxxxx>]

Hi Guys,

1) I'm all for a combined project.

2) I don't want to start another mine is better than yours discussion, but,
I use AVR's :) I have a great compiler AVRCo with true multitasking etc

3) I think that a dedicated 485 network controller will be required. I
think
the 485 comms will probably run about 38400 baud.
A 16MHz AVR will happily look after this.
The network controller will pass and receive all state changes to the PC
as well as heart beats for each device.
Comms to the PC could be 9600.

4) I envisage that there be at least two types of room controllers (Perhaps
we should start by settling on some names for these things)
a) Bedroom/kitchen/Living area Controller wish list
Display,
Personnel Switches for lights, sound muting etc,
Data entry method, Set room alarm clock time etc Sleep time for
lighting etc
IR Transmitter, Turn telly off when I fall asleep in bed, turn
ceiling fan off etc etc
Personal ID method
Sound
Movement sensor interface
Switch inputs for door & window reed switches

b) Basic room as in garage/toilet/bathroom wish list
Personnel Switches for lights etc,
Sound
Movement sensor interface
Switch inputs for door & window reed switches
Note - This is to be a cheaper version, no display only beeper for
sound alerts, maybe a IR receiver for configuration ??

Hardware Solutions for above
Display,
16*2 LCD with LED backlight OR maybe a small graphic LCD, could display
small icons for

you have email, voice messages, phone callers etc.
Personnel Switches for lights etc,                             2..4
Tactile switches I.e. small PCB mount
Light Control
either 240V relay or triac, triac allows dimming, great for those wee stops
in the night
Data entry method,
Universal TV remote. I can currently decode Sony or RC5 signals
IR Transmitter
IR led on controller as well as capability to add an external IR led else
where in the room

for better coverage if needed, I.e. Living room with external LED for
Stereo
etc.
Personal ID method
Dallas 1 wire ibutton, A lot cheaper & smaller than RFID!
Sound
2 Types, 1) Standard beeper. 2) Optional 1W speaker with sound relaying
from
controller Pc

Probably a separate optional PCB.
Movement sensor interface                                    As
suggested either a integrated unit actually on the controller or a separate
security PIR
Switch inputs for door & window reed switches        Standard style
of inputs on a micro 5..12V tolerant.

Power Supply and Signal
I suggest that we use CAT5
Power - 2 Pairs 1 pair for 0V and one pair for +24V.
Comms Signal  - 1 Pair
Audio from PC - 1 Pair
If we try to use the standard pin outs for power over Ethernet
and data signals, nothing will be damaged if
a wrong device is plugged in somewhere.
Although, I did see these devices as being panel mounted on the
walls.


Regards,

Neil Wrightson.
-----Original Message-----
From: Frank Mc Alinden [mailto:fmcalind@xxxxxxx]
Sent: Monday, 24 January 2005 12:29 PM
To: ukha_xpl@xxxxxxx
Subject: Re: [ukha_xpl] Re: Serial protocol questions



Hi Ben
I was also thinking of having a little box in each room  which
has an lcd display , rfid reader and a small pir head for Occupancy
detection.....Would be good to throw a few ideas around ...and  as you say
have a common rs485 protocol.......

BTW..........Are you on the piclist ???

Frank
.


----- Original Message -----
From: "DynamoBen" <ben@xxxxxxx>
To: <ukha_xpl@xxxxxxx>
Sent: Monday, January 24, 2005 9:56 AM
Subject: RE: [ukha_xpl] Re: Serial protocol questions


>
> Neil,
>
> Your protocol design is very similar to what I had originally planned
prior
> to stumbling across the xpl documentation.
>
> You made and interesting point that I had not thought about in my
design.
I
> had assumed that on the PC side of things I would just drop in an
> RS232->RS485 converter and call it done. Now I'm contemplating
using a pic
> as a master and making the door locations slaves.
> Would that makes sense? Is it worth the extra work?
>
> Additionally, I think what you're working on and what I'm working on
could
> be very complementary. Is it worthwhile to work together on system
layout
> and protocol so that both our devices "play" on the same
RS485 network? I
> think in doing that we will indirectly create somewhat of an xpl
standard
in
> that one plug-in can be created for all RS485 devices. That plug-in
would
> convert RS485 message into xpl network messages. Is my thinking
correct?
>
> -----Original Message-----
> From: Neil Wrightson [mailto:neilw@xxxxxxx]
> Sent: Sunday, January 23, 2005 6:06 AM
> To: ukha_xpl@xxxxxxx
> Subject: RE: [ukha_xpl] Re: Serial protocol questions
>
>
> Frank,
>
> Firstly, I'm not sure if everybody is up to speed on RS485 comms.
RS485
uses
> 2 wires for the transmission of data. For simplicities sake, lets
treat
the
> two wires as one.
> As you would appreciate, you cannot typically send and receive data on
a
> single wire at the same time. Thus a master is required that transmits
out
a
> signal, and at the same time slaves are awaiting a signal. When a
slave
> receives a message specifically address to it, it then talks back to
the
> master. The actual RS485 IC's in the master and slaves must be changed
from
> Transmission mode to receive and back again for each sent message.
> Basically it goes like this -
>
> Master
> Slave
> 1) Set Master RS485 IC to Transmit mode
> Set RS485 IC to Receive mode
>     (Usually RTS signal on comm port)
> 2) Transmit Message to Slave #03
> Receive message
> 3) Set Master RS485 IC to Receive mode (Usually RTS signal on comm
port)
> If it was for me then process
> 4) Wait for message from Slave #03
> All of my messages require an acknowledge
>     (Usually includes a timeout in case slave #03 does not respond)
> So set RS485 IC to Transmit mode and send message
> 5) Optional delay
> Set RS485 to Receive mode
> 6) Goto 1) or poll extra slaves etc
> Wait for next message
>
>
> I use two different protocols depending on the application.
> 1) PC to RS485 Devices
> The communications are between the PC and the remote RS485 slave
devices.
A
> RS232 to RS485 converter is required for the PC.
> This converter can be quite simple and does not require any brains
I.e. no
> processor.
> Although optical isolation at this point is nice (Adds $$$ but not
much)
> Basically the comms are as per above sample. The PC must be able to
toggle
> the RTS line for each transmission. Sounds simple but, the PC software
must
> know when the last character has been completely sent out of the UART
in
the
> serial interface. Most PC's are at least double buffered, or even 8 or
16
> character buffer. So doing something simple in Pascal like saying
send(Ch);
> SetRTS(Low); would be guaranteed to not work.
> Having said that, the protocol I use is
> 1    Stx                        Byte,#02
> 2    Addr                      Byte 0..255    Note Generally RS485
limits
32
> devices to be connected to the bus
> 3    Message Length     Byte              Allows messages up to 256 -
> Message size
> 4    Command              Byte              I.e.Clear LCD display,
Obtain
> I/O status etc
> 5    Data if any             Variable size based on message length.
could
be
> zero
> 6    Checksum             Byte               Checksum of bytes from
Stx to
> Checksum location minus 1
> 7    Etx                       Byte, #03
>
> Thus the minimum message sizes is 6 bytes if no extra data is
transmitted
>
>
> 2) PC to Dedicated master to slaves
> The first part of PC to dedicated master is as per the above protocol.
The
> big difference here is that the PC to master interface is RS232, thus
none
> of the waffle with concerns about the RTS handshaking lines being
changed
> over at the wrong time. Just 3 wires Tx,Rx,0V.
> The Master is a separate dedicated micro controller board that talks
RS232
> to the PC and talks RS485 to the slaves.
> Here the protocol is somewhat different because of the features within
the
> dedicated micros
> 1    Address                Byte or Word    - Well not quite These
> particular bytes are actually 9 bits in size
> 2    Message Length    Byte
> 3    Data                     Variable size based on message length.
could
> be zero
> 4    Checksum
>
> Good points about this method are that the local RS485 network can be
very
> fast and the master is always aware of all changes. It then only
passes
> state changes to the PC via the RS232 port. Usual delays in PC's I.e.
> disappearing for a second do not effect the RS485 comms.
>
> Both protocols use an address of 0 (Zero) for general broadcasting of
> messages to all devices. I.e. perform a master reset.
>
>
> In other postings I have made reference to a remote RS485 terminal
with
LCD,
> keypad, I/O, IR Tx & Rx etc that is under development.
> What I plan is that basically this terminal will be a ROOM terminal
and
have
> some smart intelligence built in.
> I.e.
>     I/O Inputs for PIR's (Movement sensor) and door/window switches
(These
> will be interfaced to the lights for auto light control as well as
security)
>     I/O Outputs for Lights, sound etc
>     Audio Out - Thinking of relaying HAPC voice annunciations
>     RTC for determining wake up alarms, sleep modes etc.
>
> My idea is that, even if the HAPC or the RS485 network is down a
person
> should still be able to turn the lights OFF/ON etc NOT have the house
in a
> completely shut down mode and stumbling around in the dark.
> Here I see that the slave room terminals will need to pass all state
changes
> back and forth to the master and to the PC. BUT each slave must be
able to
> see an input change I.e. PIR picks up movement and it MUST then turn
on
the
> light. It can't wait for it to send a message to the PC saying
movement
and
> the PC then respond back with turn on the light.
>
> All of the above I do now in various forms. To me the embedded side is
easy.
> Your PC xPL is a bit different. I could do a separate windows app
using
> Delphi for the xPL IP socket to serial port connection but I think it
would
> be better added into xPLHAL or something ???
>
> Well, time to go to bed. Work tomorrow :(
>
> Hey Frank, I just noticed your email is bigpond.net.au. Are you in
AUS?
I'm
> in the Newcastle region.
>
>
> Regards,
>
> Neil Wrightson.
>
> From: Frank Mc Alinden [mailto:fmcalind@xxxxxxx]
> Sent: Sunday, 23 January 2005 6:39 PM
> To: ukha_xpl@xxxxxxx
> Subject: Re: [ukha_xpl] Re: Serial protocol questions
>
>
>
> Hi Ben
>             I was thinking if Neil already has a reasonably simple and
> robust  rs485 protocol for his kit , why not look at that and take it
from
> there ...???
>
> Frank
>
> ----- Original Message -----
> From: <ben@xxxxxxx>
> To: <ukha_xpl@xxxxxxx>
> Sent: Sunday, January 23, 2005 5:52 PM
> Subject: [ukha_xpl] Re: Serial protocol questions
>
>
> >
> >
> >
> > 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.xplproject.org.uk <http://www.xplproject.org.uk>
>
> > < http://www.xplproject.org.uk <http://www.xplproject.org.uk> 
<
http://www.xplproject.org.uk
<http://www.xplproject.org.uk>
> >
> > > http://www.xplhal.com
<http://www.xplhal.com>  < http://www.xplhal.com
<http://www.xplhal.com> > 
< http://www.xplhal.com <http://www.xplhal.com>
> < http://www.xplhal.com <http://www.xplhal.com> > >
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<
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> > > >
> > > >
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> > > >
> > > >
> > >
> > >
> > >
> > > xPL Links: http://www.xplproject.org.uk <http://www.xplproject.org.uk>
< http://www.xplproject.org.uk <http://www.xplproject.org.uk>
>
> > < http://www.xplproject.org.uk <http://www.xplproject.org.uk> 
<
http://www.xplproject.org.uk
<http://www.xplproject.org.uk>
> >
> > > http://www.xplhal.com
<http://www.xplhal.com>  < http://www.xplhal.com
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< http://www.xplhal.com <http://www.xplhal.com>
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< http://www.xplproject.org.uk <http://www.xplproject.org.uk>
>
> http://www.xplhal.com <http://www.xplhal.com>  < http://www.xplhal.com
<http://www.xplhal.com> >
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<
http://www.xplproject.org.uk
<http://www.xplproject.org.uk>
>
> http://www.xplhal.com <http://www.xplhal.com>  < http://www.xplhal.com
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