Incredible! Thanks, Tim.
On Friday, 13 April 2012 17:12:44 UTC-4, Tim Caswell wrote:
>
> Try this:
>
> function calcChecksum(string) {
> var buf = new Buffer(string);
>
> // Calculate the modulo 256 checksum
> var sum = 0;
> for (var i = 0, l = buf.length; i < l; i++) {
> sum = (sum + buf[i]) % 256;
> }
> // Find the compliment
> sum = 256 - sum;
>
> // Convert to a two byte uppercase hex value
> var chars = sum.toString(16).toUpperCase();
> if (chars.length ==1 ) chars = "0" + chars;
> return chars;
> }
>
> On Fri, Apr 13, 2012 at 4:03 PM, Tim Caswell <[email protected]> wrote:
>
>> Looks like you're missing the two's compliment part and the upper case
>> part.
>>
>>
>> On Fri, Apr 13, 2012 at 3:54 PM, Kevin O <[email protected]> wrote:
>>
>>> I am working on a node integration to a home automation device. The
>>> device has an ASCII protocol that I am building a parser and a command
>>> generator for.
>>>
>>> All of the ASCII messages that I send need to be appended with modulo
>>> 256 checksum. Here is the exact verbiage from the documentation.
>>>
>>> 2-digit checksum: This is the hexadecimal two’s complement of the
>>>> modulo-256 sum of the ASCII values of all characters in the message
>>>> excluding the checksum itself and the CR-LF terminator at the end of the
>>>> message. Permissible characters are ASCII 0-9 and upper case A-F. When all
>>>> the characters are added to the Checksum, the value should equal 0.
>>>>
>>>
>>> I have an ASCII string of *09sw13100* that is supposed to result in hex
>>> *B8. *That is what I am using as my test.
>>>
>>> Any ideas on how to implement this? I've tried the function below but it
>>> produces the wrong output.
>>>
>>> function calcChecksum(asciiString) {
>>> var buf = new Buffer(asciiString);
>>> var sum = 0;
>>> for(var i=0; i<buf.length; i++) {
>>> sum = sum + buf[i];
>>> }
>>> sum = sum%256;
>>> return sum.toString(16);
>>> }
>>>
>>> --
>>> Job Board: http://jobs.nodejs.org/
>>> Posting guidelines:
>>> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
>>> You received this message because you are subscribed to the Google
>>> Groups "nodejs" group.
>>> To post to this group, send email to [email protected]
>>> To unsubscribe from this group, send email to
>>> [email protected]
>>> For more options, visit this group at
>>> http://groups.google.com/group/nodejs?hl=en?hl=en
>>>
>>
>>
>
On Friday, 13 April 2012 17:12:44 UTC-4, Tim Caswell wrote:
>
> Try this:
>
> function calcChecksum(string) {
> var buf = new Buffer(string);
>
> // Calculate the modulo 256 checksum
> var sum = 0;
> for (var i = 0, l = buf.length; i < l; i++) {
> sum = (sum + buf[i]) % 256;
> }
> // Find the compliment
> sum = 256 - sum;
>
> // Convert to a two byte uppercase hex value
> var chars = sum.toString(16).toUpperCase();
> if (chars.length ==1 ) chars = "0" + chars;
> return chars;
> }
>
> On Fri, Apr 13, 2012 at 4:03 PM, Tim Caswell <[email protected]> wrote:
>
>> Looks like you're missing the two's compliment part and the upper case
>> part.
>>
>>
>> On Fri, Apr 13, 2012 at 3:54 PM, Kevin O <[email protected]> wrote:
>>
>>> I am working on a node integration to a home automation device. The
>>> device has an ASCII protocol that I am building a parser and a command
>>> generator for.
>>>
>>> All of the ASCII messages that I send need to be appended with modulo
>>> 256 checksum. Here is the exact verbiage from the documentation.
>>>
>>> 2-digit checksum: This is the hexadecimal two’s complement of the
>>>> modulo-256 sum of the ASCII values of all characters in the message
>>>> excluding the checksum itself and the CR-LF terminator at the end of the
>>>> message. Permissible characters are ASCII 0-9 and upper case A-F. When all
>>>> the characters are added to the Checksum, the value should equal 0.
>>>>
>>>
>>> I have an ASCII string of *09sw13100* that is supposed to result in hex
>>> *B8. *That is what I am using as my test.
>>>
>>> Any ideas on how to implement this? I've tried the function below but it
>>> produces the wrong output.
>>>
>>> function calcChecksum(asciiString) {
>>> var buf = new Buffer(asciiString);
>>> var sum = 0;
>>> for(var i=0; i<buf.length; i++) {
>>> sum = sum + buf[i];
>>> }
>>> sum = sum%256;
>>> return sum.toString(16);
>>> }
>>>
>>> --
>>> Job Board: http://jobs.nodejs.org/
>>> Posting guidelines:
>>> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
>>> You received this message because you are subscribed to the Google
>>> Groups "nodejs" group.
>>> To post to this group, send email to [email protected]
>>> To unsubscribe from this group, send email to
>>> [email protected]
>>> For more options, visit this group at
>>> http://groups.google.com/group/nodejs?hl=en?hl=en
>>>
>>
>>
>
On Friday, 13 April 2012 17:12:44 UTC-4, Tim Caswell wrote:
>
> Try this:
>
> function calcChecksum(string) {
> var buf = new Buffer(string);
>
> // Calculate the modulo 256 checksum
> var sum = 0;
> for (var i = 0, l = buf.length; i < l; i++) {
> sum = (sum + buf[i]) % 256;
> }
> // Find the compliment
> sum = 256 - sum;
>
> // Convert to a two byte uppercase hex value
> var chars = sum.toString(16).toUpperCase();
> if (chars.length ==1 ) chars = "0" + chars;
> return chars;
> }
>
> On Fri, Apr 13, 2012 at 4:03 PM, Tim Caswell <[email protected]> wrote:
>
>> Looks like you're missing the two's compliment part and the upper case
>> part.
>>
>>
>> On Fri, Apr 13, 2012 at 3:54 PM, Kevin O <[email protected]> wrote:
>>
>>> I am working on a node integration to a home automation device. The
>>> device has an ASCII protocol that I am building a parser and a command
>>> generator for.
>>>
>>> All of the ASCII messages that I send need to be appended with modulo
>>> 256 checksum. Here is the exact verbiage from the documentation.
>>>
>>> 2-digit checksum: This is the hexadecimal two’s complement of the
>>>> modulo-256 sum of the ASCII values of all characters in the message
>>>> excluding the checksum itself and the CR-LF terminator at the end of the
>>>> message. Permissible characters are ASCII 0-9 and upper case A-F. When all
>>>> the characters are added to the Checksum, the value should equal 0.
>>>>
>>>
>>> I have an ASCII string of *09sw13100* that is supposed to result in hex
>>> *B8. *That is what I am using as my test.
>>>
>>> Any ideas on how to implement this? I've tried the function below but it
>>> produces the wrong output.
>>>
>>> function calcChecksum(asciiString) {
>>> var buf = new Buffer(asciiString);
>>> var sum = 0;
>>> for(var i=0; i<buf.length; i++) {
>>> sum = sum + buf[i];
>>> }
>>> sum = sum%256;
>>> return sum.toString(16);
>>> }
>>>
>>> --
>>> Job Board: http://jobs.nodejs.org/
>>> Posting guidelines:
>>> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
>>> You received this message because you are subscribed to the Google
>>> Groups "nodejs" group.
>>> To post to this group, send email to [email protected]
>>> To unsubscribe from this group, send email to
>>> [email protected]
>>> For more options, visit this group at
>>> http://groups.google.com/group/nodejs?hl=en?hl=en
>>>
>>
>>
>
On Friday, 13 April 2012 17:12:44 UTC-4, Tim Caswell wrote:
>
> Try this:
>
> function calcChecksum(string) {
> var buf = new Buffer(string);
>
> // Calculate the modulo 256 checksum
> var sum = 0;
> for (var i = 0, l = buf.length; i < l; i++) {
> sum = (sum + buf[i]) % 256;
> }
> // Find the compliment
> sum = 256 - sum;
>
> // Convert to a two byte uppercase hex value
> var chars = sum.toString(16).toUpperCase();
> if (chars.length ==1 ) chars = "0" + chars;
> return chars;
> }
>
> On Fri, Apr 13, 2012 at 4:03 PM, Tim Caswell <[email protected]> wrote:
>
>> Looks like you're missing the two's compliment part and the upper case
>> part.
>>
>>
>> On Fri, Apr 13, 2012 at 3:54 PM, Kevin O <[email protected]> wrote:
>>
>>> I am working on a node integration to a home automation device. The
>>> device has an ASCII protocol that I am building a parser and a command
>>> generator for.
>>>
>>> All of the ASCII messages that I send need to be appended with modulo
>>> 256 checksum. Here is the exact verbiage from the documentation.
>>>
>>> 2-digit checksum: This is the hexadecimal two’s complement of the
>>>> modulo-256 sum of the ASCII values of all characters in the message
>>>> excluding the checksum itself and the CR-LF terminator at the end of the
>>>> message. Permissible characters are ASCII 0-9 and upper case A-F. When all
>>>> the characters are added to the Checksum, the value should equal 0.
>>>>
>>>
>>> I have an ASCII string of *09sw13100* that is supposed to result in hex
>>> *B8. *That is what I am using as my test.
>>>
>>> Any ideas on how to implement this? I've tried the function below but it
>>> produces the wrong output.
>>>
>>> function calcChecksum(asciiString) {
>>> var buf = new Buffer(asciiString);
>>> var sum = 0;
>>> for(var i=0; i<buf.length; i++) {
>>> sum = sum + buf[i];
>>> }
>>> sum = sum%256;
>>> return sum.toString(16);
>>> }
>>>
>>> --
>>> Job Board: http://jobs.nodejs.org/
>>> Posting guidelines:
>>> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
>>> You received this message because you are subscribed to the Google
>>> Groups "nodejs" group.
>>> To post to this group, send email to [email protected]
>>> To unsubscribe from this group, send email to
>>> [email protected]
>>> For more options, visit this group at
>>> http://groups.google.com/group/nodejs?hl=en?hl=en
>>>
>>
>>
>
On Friday, 13 April 2012 17:12:44 UTC-4, Tim Caswell wrote:
>
> Try this:
>
> function calcChecksum(string) {
> var buf = new Buffer(string);
>
> // Calculate the modulo 256 checksum
> var sum = 0;
> for (var i = 0, l = buf.length; i < l; i++) {
> sum = (sum + buf[i]) % 256;
> }
> // Find the compliment
> sum = 256 - sum;
>
> // Convert to a two byte uppercase hex value
> var chars = sum.toString(16).toUpperCase();
> if (chars.length ==1 ) chars = "0" + chars;
> return chars;
> }
>
> On Fri, Apr 13, 2012 at 4:03 PM, Tim Caswell <[email protected]> wrote:
>
>> Looks like you're missing the two's compliment part and the upper case
>> part.
>>
>>
>> On Fri, Apr 13, 2012 at 3:54 PM, Kevin O <[email protected]> wrote:
>>
>>> I am working on a node integration to a home automation device. The
>>> device has an ASCII protocol that I am building a parser and a command
>>> generator for.
>>>
>>> All of the ASCII messages that I send need to be appended with modulo
>>> 256 checksum. Here is the exact verbiage from the documentation.
>>>
>>> 2-digit checksum: This is the hexadecimal two’s complement of the
>>>> modulo-256 sum of the ASCII values of all characters in the message
>>>> excluding the checksum itself and the CR-LF terminator at the end of the
>>>> message. Permissible characters are ASCII 0-9 and upper case A-F. When all
>>>> the characters are added to the Checksum, the value should equal 0.
>>>>
>>>
>>> I have an ASCII string of *09sw13100* that is supposed to result in hex
>>> *B8. *That is what I am using as my test.
>>>
>>> Any ideas on how to implement this? I've tried the function below but it
>>> produces the wrong output.
>>>
>>> function calcChecksum(asciiString) {
>>> var buf = new Buffer(asciiString);
>>> var sum = 0;
>>> for(var i=0; i<buf.length; i++) {
>>> sum = sum + buf[i];
>>> }
>>> sum = sum%256;
>>> return sum.toString(16);
>>> }
>>>
>>> --
>>> Job Board: http://jobs.nodejs.org/
>>> Posting guidelines:
>>> https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
>>> You received this message because you are subscribed to the Google
>>> Groups "nodejs" group.
>>> To post to this group, send email to [email protected]
>>> To unsubscribe from this group, send email to
>>> [email protected]
>>> For more options, visit this group at
>>> http://groups.google.com/group/nodejs?hl=en?hl=en
>>>
>>
>>
>
--
Job Board: http://jobs.nodejs.org/
Posting guidelines:
https://github.com/joyent/node/wiki/Mailing-List-Posting-Guidelines
You received this message because you are subscribed to the Google
Groups "nodejs" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/nodejs?hl=en?hl=en
