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simonvetter / modbus

Go modbus stack (client and server)
MIT License
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uint32 LittleEndian wrong byteorder #25

Closed linuxnase closed 1 year ago

linuxnase commented 1 year ago

Hi Simon, there is a bug in the byte order when calling little endian conversion binary.LittleEndian.Uint32. (encoding.go, func bytesToUint32s)

case LITTLE_ENDIAN:
    if wordOrder == LOW_WORD_FIRST {
        u32 = binary.LittleEndian.Uint32(in[i:i+4])
    } else {
        u32 = binary.LittleEndian.Uint32(
            []byte{in[i+2], in[i+3], in[i+0], in[i+1]})   <--- same order as in the BIG_ENDIAN case!!

should be:

u32 = binary.LittleEndian.Uint32(
    []byte{in[i+1], in[i+0], in[i+3], in[i+2]})
shuzhongling commented 1 year ago

i think this isn't wrong. in a word register, it is LITTLE endian, when read a dword, the word order is high word first.

simonvetter commented 1 year ago

Glad you found out that everything works properly :) I'm going to go ahead and close this, feel free to reopen if needed.