Re: Parsing binary data from an RS232 connection

[Cedric Mauclair <cedric.mauclair@...>]

On December 7, 2019 10:00:46 AM UTC, Marc Balmer <marc@msys.ch> wrote:
>We have a module 'csp' (Characater Sequence Parser) for this, where you
>can define sequences to be detected in data streams and call a function
>if the sequence pattern gets detected:
>
>local p = csp.new(defaultHandler)
>
>p:sequence('\027*', reset)
>p:sequence('\027!', softReset)
>p:sequence('\027B0', b0)
>p:sequence('\027B1', b1)
>p:sequence('\013', function () print('newline') end)
>p:sequence('\029A0', b0)
>p:sequence('\029A3', b1)
>p:sequence('\027B%c-', b)
>p:sequence('\029B%c', b)
>p:sequence('\027=%c%c', pos)
>p:sequence('\x05%S\x0d', function (s) print('string', s) end)
>
>-- decimals
>
>p:sequence('\027[%d', decimal)
>p:sequence('\027p%d;', decimal)
>
>p:dump()
>
>p:parse('\027[45x\n')
>p:parse('\027p42;abc\n')
>
>We used it to decode ESC/POS printer commands.
>
>Nut sure though if this would match you usecase.
>
>> Am 07.12.2019 um 03:38 schrieb Tim McCracken
><Tim.McCracken@Utelety.com>:
>> 
>>  
>> Does anyone have a suggestion for parsing the data or even an
>existing project? Any and all input is welcome.
>>  
>> Thanks!
>> Russell
>>  
>>  
>> Russell,
>> I have been working on a “smart buffer” for just this issue, although
>it is not complete yet. However, it might give you some ideas on how to
>proceed. It is NOT pure Lua, but rather consists of two userdata object
>– the “smart buffer” and the serial port driver that takes the smart
>buffer as an argument.
>>  
>> The serial port driver simply reads and writes binary data from the
>smart buffer. Then in Lua, the application can read and write various
>sized variables from the smart buffer. For example, the library has the
>following functions/methods:
>>  
>> Sequential Access: (pushes to the TX buffer, pops from the RX buffer)
>> get_byte(), get_word(), put_word(value)
>>  
>> Random Access:
>> get_byte(offset), get_word(access), put_word(offset, value)
>>  
>> Of course, if you are writing a userdata library, it may be just as
>easy to fully decode the serial protocol in ‘C’ and use callbacks to
>Lua to process the data. In my experience, this may actually be a
>better approach for “structured” protocols such as those used for
>industrial automation (Modbus) or SCADA (DNP3).
>>  
>> Tim

Hi everyone,

Seems like a very interesting module. Is it sharable?
-- 
CM.