Maybe the better way to concatenate 2 eight bit values into a 16 bit value would
 be something like this:

union word_byte_u
{
    unsigned char       low_byte;   /* the order of low_byte and high_byte
 declaration */
    unsigned char       high_byte;  /* would be compiler specific */
    unsigned long       the_word;
} u_convert;

Then when you wanted to convert two bytes to one word in your code:

u_convert.low_byte = low_val;
u_convert.high_byte = high_val;
answer = u_convert.the_word;

Classic use of union.....

-Bill