Re: Re: Serial protocol questions

["DynamoBen" <ben@xxxxxxxxxxx>]

This is what xAP has to offer. I say we use a similar model:

Basic Serial Transport Wrapper
The xAP transport wrapper for a basic serial connection is defined as
follows:

a.. The xAP message is prefixed with the ASCII control character
<STX>
(ASCII character decimal 2)
b.. The core xAP message is transmitted. Any instances of the <STX>
character and <ETX> character (ASCII characters decimal 2 and decimal
3
respectively) are escaped by prefixing the character with <ESC>
(ASCII
character 27). i.e. an embedded <STX>   becomes <ESC>
<STX> and an embedded
<ETX> becomes <ESC> <ETX> . This mechanism is defined
here for completeness;
in practice it would be very unusual to transmit non-printable characters
as
part of a xAP message.
c.. Instances of the <ESC> character  (ASCII character 27) are also
escaped. i.e. <ESC>  becomes <ESC> <ESC>. Again, it would
be rare to embed
<ESC> characters within a xAP message in practice.
d.. At the end of the xAP message a 16-bit CRC checksum is appended as
four ASCII-hex digits (ie. human readable, not binary). The checksum is
applied to all data within the message envelope: the <STX>, checksum
itself,
and <ETX> character are not included in the CRC calculation.  Hex
digits A-F
are represented in upper case. Source code examples illustrating the
calculation of 16-bit CRC checksums can be found at
www.planetsourcecode.com.
e.. If the checksum is not calculated, four dashes (ASCII code decimal 45)
are substituted in its place.
f.. The checksum is immediately followed by <ETX> (ASCII character
decimal
3)
What I suggested is similar. The biggest difference is the check sum. Here
they use 16-bit crc. To me this is way to much math for a pic processor. I
say we just do a byte add and call it done.
In the version I sent out I included <Command> based on Franks
protocol. Is
it worth keeping?

BTW they refer to their protocol converter (Master) as a
"bridge." Not a bad
term inplace of master.
----- Original Message -----
From: "g8kmh" <lehane@xxxxxxx>
To: <ukha_xpl@xxxxxxx>
Sent: Monday, January 24, 2005 3:42 PM
Subject: [ukha_xpl] Re: Serial protocol questions


>
>
> --- In ukha_xpl@xxxxxxx, "DynamoBen" <ben@b...> wrote:
>> BTW 1/8 fuses on the data line is always a good idea.
>
> Not sure what is being protected.. if I got 240v on the data line
> then some interfaces are dead and I need to get the soldering iron
> out. If the fuses blow, the same (given the space requirements they
> may be PCB mounted). OK, OK, it's easier to swap a 1206 fuse...
>
> My preference is zener clamping, spark gaps and Varistors.
>
> In answer to some other questions  (not Ben's):
>
> EPC and ISO 18000-6 relate to RFID tags which you'll see on all
> products as an adjunct and eventual replacement of bar codes on
> everything.
>
> A standard ISO based magnetic (MSR) card has three tracks containing
> various amounts of data. Track 2 on a credit/debit card has the basic
> information, Track 1 usually has the cardholder name and other info.
> Track 3 gets used by banks/ATM's.
>
> There are many barcode specifications - the ones on baked beans are
> UPC/EAN but you'll find many others on parcels, pharmaceuticals, etc.
> Off the shelf readers will read most of them and tell you what type
> by a prefix character ahead of the data.
>
> Digital input can easily handle switches with some optional on board
> pull up resistors.
>
> Lehane
>
>
>
>> ----- Original Message -----
>> From: "DynamoBen" <ben@b...>
>> To: <ukha_xpl@xxxxxxx>
>> Sent: Monday, January 24, 2005 2:53 PM
>> Subject: Re: [ukha_xpl] Re: Serial protocol questions
>>
>>
>> >
>> > RS485 hubs are super easy to build. In fact you could mock
one up
> on a
>> > breadboard in under 30mins. (They are generally called opto
> splitters)
>> >
>> > Parts Needed:
>> > Several 75176 chips (less than 32)
>> > Several 6N137 chips (this is for opto isloation)
>> >
>> > Data path is RS485-->75176 Input-->6N137
>> >
>> > Then this would be repeated for the outputs. Don't for get to
tie
> TX to
>> > RX.
>> >
>> > This make sense?
>> >
>> >
>> > ----- Original Message -----
>> > From: "Frank Mc Alinden" <fmcalind@b...>
>> > To: <ukha_xpl@xxxxxxx>
>> > Sent: Monday, January 24, 2005 2:46 PM
>> > Subject: Re: [ukha_xpl] Re: Serial protocol questions
>> >
>> >
>> >>
>> >> Hi Guys
>> >>        Have to agree with  Lehane that its better to have
lots
> of small
>> >> devices than to make one that does all ...........
>> >> Would that mean then a rs485 hub would be required so
that it
> could be
>> >> star
>> >> wired ??? anybody did a rs485 hub before ????
>> >>
>> >> Allowing the network to run at different baud rates is a
good
> idea
>> >> ,anything
>> >> i have done is 9600 , although i dont think 19200 would
be out
> of the
>> >> question for most pics...??
>> >>
>> >> The important thing to get this project going i think is
to get
> started
>> >> on
>> >> the master device....
>> >>
>> >> Neil  do you have any current hardware to develope a
Master
> on ????
>> >>
>> >>> 2) Presumably the host software will do the
device/instance id-
>>node
>> >>> number conversion and the device/instance config? -
Don't know
> what this
>> >> is
>> >>> yet ???
>> >>
>> >> Each node has a name / id and its configurable , so when
you put
> a new
>> >> device on the network it will sent out regular requests
"please
> configure
>> >> me" known as config heartbeats....The master should
pick up this
> message
>> >> and
>> >> pass it on to the xPL network....In xPL Manager under xPL
>> >> devices,subfolder
>> >> awaiting configuration the device should be listed
clicking on
> it then
>> >> allows you to configure....The config info would get send
to the
> Master
>> >> which passes it on to the new unit which would
reconfigure its
> self and
>> >> immediately send out a regular heartbeat.....
>> >> Hope that makes sense ??
>> >>
>> >> Frank
>> >>
>> >>
>> >> ----- Original Message -----
>> >> From: "Neil Wrightson" <neilw@n...>
>> >> To: <ukha_xpl@xxxxxxx>
>> >> Sent: Tuesday, January 25, 2005 7:21 AM
>> >> Subject: RE: [ukha_xpl] Re: Serial protocol questions
>> >>
>> >>
>> >>>
>> >>> Hi Lehane,
>> >>>
>> >>> 1) I made reference to the compiler I use purely
because it is
> a good
>> >>> compiler. Each different type of slave could be a
completely
> different
>> >> micro
>> >>> and language - assembler, C, Basic Pascal etc etc.
The main
> thing is
>> >>> that
>> >>> handles its own task and interfaces to the required
485 network
>> >>> protocol.
>> >>>
>> >>> 2) Presumably the host software will do the
device/instance id-
>>node
>> >>> number conversion and the device/instance config? -
Don't know
> what this
>> >> is
>> >>> yet ???
>> >>>
>> >>> 3) "Mmm!
>> >>> I'd caution against making the devices too complex.
Better have
> 10
>> >>> types (smaller/cheaper) than 1 do-everything and they
are
> likely to
>> >>> see the light of day faster. You can always put
two/three/four
> in one
>> >>> box." - Exactly
>> >>>
>> >>>
>> >>> 4) "So I'd go for:
>> >>> 1 n-way DC input (maybe analogue) variations can
include on/off,
>> >>> momentary, dimmer action, etc.
>> >>> 2 n-way DC output (maybe PWM on some for LED's)
variations -
> opto,
>> >>> SSR, etc
>> >>> 3 LCD display driver
>> >>> 4 RFID (...and RFID to me is EPC/ISO 18000)
>> >>> 5 Universal IR (UIRT on 485)
>> >>> 6 Dallas touch and/or one wire sensors
>> >>> 7 MSR (Track 1/2/3)
>> >>> 8 Bar Code Reader (UPC/EAN/ITF/Code 39)
>> >>> 9 Analog input/output (0-5/10V)
>> >>> 10 .... "
>> >>>
>> >>> A) I was thinking of analogue inputs for switches
etc, adds
> additional
>> >>> security to remote switches I.e. window reed switches
or PIR's
>> >>>
>> >>> B) What is "EPC/ISO 18000"
>> >>>
>> >>> C) What is MSR (Track 1/2/3)
>> >>>
>> >>>
>> >>>
>> >>> 5) "Agree on the power to the unit, although
12-15V maybe
> sufficient as
>> >>> the power consumption is going to be pretty low on
most.
>> >>> Not sure about the audio..I think that belongs on
Ethernet in
> the
>> >>> digital domain. I guess you're looking at voice/audio
feedback
> but
>> >>> would you want output from every device? Or would you
command
> each
>> >>> amp on? "
>> >>> RS485 Cabling is generally as per the old coax
10base2, one
> long line
>> >>> with
>> >>> terminators on either end.
>> >>> With up to 32 devices on this line, that means 64
connections,
> each with
>> >>> it's own voltage drop. The higher you can have the
supply
> voltage the
>> >>> less
>> >>> current in the supply lines the less voltage drop on
the cable
> and the
>> >> less
>> >>> impact of voltage drops on the network connectors.
>> >>> A lot of filed devices requires 12VDC so you would at
least
> have to add
>> >> 50%
>> >>> i.e. 18VDC for the interconnecting power supply. I
know of lots
> of off
>> >>> the
>> >>> shelf 24VDC supplies out there. But, I think that as
long as we
> design
>> >>> the
>> >>> system so that it can handle from 12..24VDC, we can
leave it up
> to the
>> >>> individual.
>> >>>
>> >>> 6) As far as the audio goes, my intention was that we
use the
> speaker
>> >>> out
>> >> of
>> >>> the HA pc. Nothing fancy.
>> >>> I see this as been a separate plug in add on board to
the main
> slave
>> >>> terminal with a small amp etc.
>> >>>
>> >>>
>> >>> 7) RS485 Comms Speed
>> >>> For each slave the master must Tx a message and then
Rx a
> message. 32
>> >> Slaves
>> >>> times * 2 * Packet size of say ten characters = 640
bytes. At
> 9600 baud
>> >> this
>> >>> would mean dial around would take 1.5 seconds. In
reality this
> would be
>> >>> somewhat longer with internal delays etc. Hence the
reason that
> I
>> >> suggested
>> >>> 38400 baud. I know basic chips may have issues with
this. Again
> perhaps
>> >> user
>> >>> definable 9600/38400.
>> >>> Build the network to your own needs.
>> >>>
>> >>>
>> >>> Neil.
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> written in a completely differant language or
>> >>>
>> >>>
>> >>> Regards,
>> >>>
>> >>> Neil Wrightson.
>> >>> -----Original Message-----
>> >>> From: g8kmh [mailto:lehane@m...]
>> >>> Sent: Tuesday, 25 January 2005 12:46 AM
>> >>> To: ukha_xpl@xxxxxxx
>> >>> Subject: [ukha_xpl] Re: Serial protocol questions
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> I've dropped my response in below.
>> >>>
>> >>> Lehane
>> >>>
>> >>> --- In ukha_xpl@xxxxxxx, "Neil Wrightson"
<neilw@n...>
> wrote:
>> >>> > 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
>> >>>
>> >>> To some extent it is irrelevent to most end-users.
Few are
> going to
>> >>> change code, some will want prog'ed devices and most
a kit (or
> at
>> >>> least PCB and CPU).
>> >>>
>> >>> The protocol outline is doable across a wide range of
devices,
> indeed
>> >>> it needs to be interoperable.
>> >>>
>> >>> >
>> >>> > 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.
>> >>> >
>> >>>
>> >>> A separate controller has some advantages of
redundancy and
>> >>> interfacing with Win* or *nix.
>> >>>
>> >>> With xPL not on the wire then heartbeats can be
different
> internally
>> >>> to externally.
>> >>>
>> >>> Presumably the host software will do the
device/instance id-
>>node
>> >>> number conversion and the device/instance config?
>> >>>
>> >>>
>> >>> > 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.
>> >>> >
>> >>> Mmm!
>> >>> I'd caution against making the devices too complex.
Better have
> 10
>> >>> types (smaller/cheaper) than 1 do-everything and they
are
> likely to
>> >>> see the light of day faster. You can always put
two/three/four
> in one
>> >>> box.
>> >>> So I'd go for:
>> >>> 1 n-way DC input (maybe analog) variations can
include on/off,
>> >>> momentary, dimmer action, etc.
>> >>> 2 n-way DC output (maybe PWM on some for LED's)
variations -
> opto,
>> >>> SSR, etc
>> >>> 3 LCD display driver
>> >>> 4 RFID (...and RFID to me is EPC/ISO 18000)
>> >>> 5 Universal IR (UIRT on 485)
>> >>> 6 Dallas touch and/or one wire sensors
>> >>> 7 MSR (Track 1/2/3)
>> >>> 8 Bar Code Reader (UPC/EAN/ITF/Code 39)
>> >>> 9 Analog input/output (0-5/10V)
>> >>> 10 ....
>> >>>
>> >>> Agree on the power to the unit, although 12-15V maybe
> sufficient as
>> >>> the power consumption is going to be pretty low on
most.
>> >>> Not sure about the audio..I think that belongs on
Ethernet in
> the
>> >>> digital domain. I guess you're looking at voice/audio
feedback
> but
>> >>> would you want output from every device? Or would you
command
> each
>> >>> amp on?
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>
>> >>> 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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>> >>>
>> >>>
>> >>>
>> >>>   _____
>> >>>
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>> >>>
>> >>>
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>> >> http://www.xpl.myby.co.uk
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>> >
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