getS7_Int error

[flanguy]

Hello, I use your library since few days and I pointed out that getS7_Int has an error

The error is in the getS7_Int() function: it uses 4 as the length in substr() instead of 2. Indeed, a Siemens S7 INT occupies 2 bytes, so the code should be:

public static function getS7_Int(string $data, int $start): int
{
return hexdec(bin2hex(substr($data, $start, 2)));
}

Kind regards,

Fabian

[flanguy]

Also, I suggest to add these two types in php-s7/phosphor7/src/s7_phphelper.php :

/**

• Reads 2 bytes from $data starting at offset $start and interprets them
• as an unsigned 16-bit integer (WORD) in Big Endian format.
• @param string $data The binary buffer.
• @param int $start The byte offset in the buffer.
• @return int The unsigned value read.
  */
  public static function getS7_Word(string $data, int $start): int {
  $sub = substr($data, $start, 2);
  $unpack = unpack("n", $sub); // "n" = unsigned short (16 bits) in Big Endian
  return $unpack[1];
  }

/**

• Reads a boolean value from $data. The boolean is stored in the byte located
• at the offset $byteOffset, at the bit position $bitOffset (0 = LSB, 7 = MSB).
• @param string $data The binary buffer.
• @param int $byteOffset The byte offset in the buffer.
• @param int $bitOffset The bit offset within that byte.
• @return bool TRUE if the specified bit is 1, FALSE otherwise.
  */
  public static function getS7_Boolean(string $data, int $byteOffset, int $bitOffset): bool {
  $byte = ord(substr($data, $byteOffset, 1));
  return (($byte >> $bitOffset) & 0x01) == 1;
  }

[dixi83]

Hi @flanguy

Thank you for your input! You are very welcome to do a Pull request!

I will look in to your suggestions but it might take a while.