Decode Data From Hex and LRC

Question

Hi i am having the following Rs485 data in that i know the value but unable to decrypt the data i am tried in taking 2's compliment but it comes to close but not get the correct data

3A 30 31 30 33 30 32 30 31 38 42 36 45 0D 0A

in above rs 485 data value is=395 that is 3842 =395 and 3645 =LRC and 0D0A=End character

3A 30 31 30 33 30 32 30 31 38 46 36 41 0D 0A

in above rs 485 data value is=399 that is 3846=399 and 3641 =LRC and 0D0A=End character

3A 30 31 30 33 30 32 30 31 39 30 36 39 0D 0A

in above rs 485 data value is=400 that is 3930 =400 and 3639 =LRC and 0D0A=End character

3A 30 31 30 33 30 32 30 31 39 32 36 37 0D 0A

in above rs 485 data value is=402 that is 3932 =402 and 3637 =LRC and 0D0A=End character

Please guide me to get LRC value and data.Lrc value is summing of data and taking 2's compliment negotion but i don't know how to take lrc value.Please help me to get data and LRC value calculation

Please guide me to get answer – Sathish Dec 11 '18 at 13:42 — Sathish, Dec 11 '18 at 13:42

rcgldr · Answer 1 · 2018-12-11T16:05:57.443

Using the first line as an example, convert the pairs of ASCII bytes in to single hex bytes:

3A 30 31 30 33 30 32 30 31 38 42 xx xx 0D 0A   ASCII
      01    03    02    01    8B               hex values converted to binary bytes
      01 +  03 +  02 +  01  + 8B  = 92         sum up the hex values
                        00  - 92  = 6E         take the two's complement
                                 36 45         convert the 6E to ASCII
3A 30 31 30 33 30 32 30 31 38 42 36 45 0D 0A   include the 36 45 into the message

For the last line:

3A 30 31 30 33 30 32 30 31 39 32 xx xx 0D 0A
      01  + 03  + 02  + 01  + 92  = 99
                        00  - 99  = 67
3A 30 31 30 33 30 32 30 31 39 32 36 37 0D 0A

Decode Data From Hex and LRC

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