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Re: Block Check Character (BCC)
Posted: Mon Mar 13, 2017 12:44 am
by Roberto Lopez
edk wrote: ↑Fri Mar 10, 2017 10:06 am
<...>
In my opinion the binary sum of all bytes is nothing but the sum of the ASCII codes of each character in the string.
From a mathematical point of view, it does not matter if we add up the number of binary, hexadecimal or decimal notation. The sum should always be the same.
For example:
the sum in binary notation : 101 + 110 = 1011; decimal = 11
the sum in decimal notation: 5 + 6 = 11
I'm surprised the given example, because the sum of all bytes (from [STX] to [ETX]) results in a hexadecimal notation 0554, not 0054.
<...>
Maybe an error on the specific example. I'll try your suggestion with the others.
edk wrote: ↑Fri Mar 10, 2017 10:06 am
Manufacturer fiscal printer does not provide any libraries to operate the device?
Yes. It provides a nice OCX and other things, but, I like do my apps portable, so I prefer not to rely on an OCX control that could generate unexpected problems.
Many thanks for your help.
Re: Block Check Character (BCC)
Posted: Mon Mar 13, 2017 12:47 am
by Roberto Lopez
mol wrote: ↑Sun Mar 12, 2017 6:21 am
I'm using such a function with communication with Polish fiscal printers to calculate CRC:
Code: Select all
function CalculateCRC
param cString
local nResult := 0xff
local nChar
local i
local cRetValue
for i:=1 to len(cString)
nChar := asc(substr(cString,i,1))
nResult := numxor(nResult, nChar)
next i
// conversion to required format - change hex to string
nChar := nResult % 16
if nChar > 9
cRetValue := chr(55+nChar)
else
cRetValue := str(nChar,1)
endif
nChar := (nResult-nChar)/16
if nChar > 9
cRetValue := chr(55+nChar) + cRetValue
else
cRetValue := str(nChar,1) + cRetValue
endif
return cRetValue
Thanks Marek!
I'll check it ASAP.
Re: Block Check Character (BCC)
Posted: Mon Mar 13, 2017 9:30 am
by edk
Roberto Lopez wrote: ↑Mon Mar 13, 2017 12:44 am
Yes. It provides a nice OCX and other things, but, I like do my apps portable, so I prefer not to rely on an OCX control that could generate unexpected problems.
I mean here the idea to see how libraries provided by the manufacturer calculate the BCC.
Re: Block Check Character (BCC)
Posted: Mon Mar 13, 2017 9:41 am
by edk
mol wrote: ↑Sun Mar 12, 2017 6:21 am
I'm using such a function with communication with Polish fiscal printers to calculate CRC:
Code: Select all
function CalculateCRC
param cString
local nResult := 0xff
local nChar
local i
local cRetValue
for i:=1 to len(cString)
nChar := asc(substr(cString,i,1))
nResult := numxor(nResult, nChar)
next i
// conversion to required format - change hex to string
nChar := nResult % 16
if nChar > 9
cRetValue := chr(55+nChar)
else
cRetValue := str(nChar,1)
endif
nChar := (nResult-nChar)/16
if nChar > 9
cRetValue := chr(55+nChar) + cRetValue
else
cRetValue := str(nChar,1) + cRetValue
endif
return cRetValue
Marku, I calculate CRC for Posnet and Thermal protocol in this way:
Code: Select all
FUNCTION CalculateCRC( cSent, cProtocol)
Local k, xCRC
DO CASE
CASE cProtocol='THERMAL'
xCRC:=255
FOR k:=3 TO LEN(TRIM(cSent))
xCRC=NUMXOR( xCRC, ASC( SUBSTR ( cSent, k, 1) ) )
NEXT
xCRC:=NTOC( xCRC, 16, 2, '0')
CASE cProtocol='POSNET'
xCRC:=NTOC(HB_CrcCt( cSent ),16)
ENDCASE
RETURN xCRC
Edward.
Re: Block Check Character (BCC)
Posted: Mon Mar 13, 2017 9:44 am
by mol
It's nice to have alternative
Thank you!
Re: Block Check Character (BCC)
Posted: Thu Mar 16, 2017 3:50 pm
by Roberto Lopez
edk wrote: ↑Mon Mar 13, 2017 9:30 am
Roberto Lopez wrote: ↑Mon Mar 13, 2017 12:44 am
Yes. It provides a nice OCX and other things, but, I like do my apps portable, so I prefer not to rely on an OCX control that could generate unexpected problems.
I mean here the idea to see how libraries provided by the manufacturer calculate the BCC.
Since the OCX methods, does not require the user to send any checksum to the printer, there is not any info about that.
I know that my attempt to not use a 'nice and easy' OCX could appear to be strange, but I always try to skip as much abstraction layers as possible. That way I (at least, theoretically) get more speed, control and stability.
Re: Block Check Character (BCC)
Posted: Thu Mar 16, 2017 3:53 pm
by Roberto Lopez
And...
I hope to have some free time during weekend, to check your suggestions and compare with the results shown in the printer manual.
Thanks again.
Re: Block Check Character (BCC)
Posted: Thu Mar 16, 2017 4:57 pm
by Roberto Lopez
Edward.
edk wrote: ↑Fri Mar 10, 2017 10:06 am
<..>
Example according to andyglezl
DecToHexa (BIntODEC (DecToBin (asciisum ("123"))))
is OK, but shorter is
NTOC( AsciiSum ( cSent ), 16, 4, '0' )
Code: Select all
STX:=CHR(2)
ESC:=CHR(27)
FS:=CHR(28)
ETX:=CHR(3)
cSent:=STX+'1'+ESC+'*'+FS+'0000'+FS+'0000'+FS+'0004'+FS+'3'+FS+'83'+FS+'81'+FS+'2'+FS+'0'+FS+'0'+ETX
BCC:=NTOC( AsciiSum ( cSent ), 16, 4, '0' ) // => '0554'
I've applied your example to some different manual examples and I've found a pattern: Simply replacing the first two digits of the result generated by your code and replacing them by '00' I get the 'correct' answers:
Code: Select all
STX := CHR(2)
ESC := CHR(27)
FS := CHR(28)
ETX := CHR(3)
/*
Manual Example:
[STX]1[ESC]*[FS]0000[FS]0000[FS]0004[FS]3[FS]83[FS]81[FS]2[FS]0[FS]0[ETX]0054
*/
cSent:=STX+'1'+ESC+'*'+FS+'0000'+FS+'0000'+FS+'0004'+FS+'3'+FS+'83'+FS+'81'+FS+'2'+FS+'0'+FS+'0'+ETX
BCC := NTOC( AsciiSum ( cSent ), 16, 4, '0' )
/*
Result: '0554'
According Manual: '0054'
*/
*-------------------------------------------------------------------------------*
cSent:=STX+'1' + ESC+'*' + FS +'81' + ETX
BCC := NTOC( AsciiSum ( cSent ), 16, 4, '0' )
/*
Result: '0100'
According Manual: '0000'
*/
*-------------------------------------------------------------------------------*
/*
Manual Example: [STX]1[ESC]@[FS]82[ETX]0017
*/
cSent:=STX+'1' + ESC+'@' + FS +'82' + ETX
BCC := NTOC( AsciiSum ( cSent ), 16, 4, '0' )
/*
Result: '0117'
According Manual: '0017'
*/
*-------------------------------------------------------------------------------*
/*
Manual Example:
[STX]1[ESC]@[FS]0000[FS]0000[FS]00000004[ETX]00E9
*/
cSent:=STX+'1' + ESC+'@' + FS +'0000' + FS + '0000' + FS + '00000004' + ETX
BCC := NTOC( AsciiSum ( cSent ), 16, 4, '0' )
/*
Result: '03E9'
According Manual: '00E9'
*/
So... I've solved my problem! (I guess:) )
I'll check with the printer emulator to see what numbers makes she happy...
Thanks!
Re: Block Check Character (BCC)
Posted: Thu Mar 16, 2017 6:41 pm
by edk
Could it be nibble?
Roberto Lopez wrote: ↑Thu Mar 09, 2017 2:43 am
(...)
The description of BCC in the manual (translated from original Spanish) is as follows:
BCC = Four hexadecimales. Binary sum of all prior bytes
It seems to me that you wrong read on the description of the calculation of BCC.
The sum of the bytes can not give a result of zero unless all bytes are equal to 0.
Edward.
Re: Block Check Character (BCC)
Posted: Fri Mar 17, 2017 2:23 am
by Roberto Lopez
edk wrote: ↑Thu Mar 16, 2017 6:41 pm
Could it be nibble?
Roberto Lopez wrote: ↑Thu Mar 09, 2017 2:43 am
(...)
The description of BCC in the manual (translated from original Spanish) is as follows:
BCC = Four hexadecimales. Binary sum of all prior bytes
It seems to me that you wrong read on the description of the calculation of BCC.
The sum of the bytes can not give a result of zero unless all bytes are equal to 0.
Edward.
The printer is new and the technology (and API) are new too (these are the first thermal fiscal printers approved here) so could be errors in the manual.
Since the tools for developers include an emulator, I'll test with it to see what happens.
Regarding the translation I've made, it is correct from the Spanish manual to English.
The problem could be that the original technology is clearly not developed here, since some commands are named in English, other in Spanish and others with a mix between the two languages. ie: VAT is named sometimes as VAT and others as IVA (Spanish acronym for Value Added Tax: Impuesto al Valor Agregado).
My guess is that this is an 'imported' technology (US?, EU?) adapted with the changes required for the local taxes.