Spectrum Controls 1769sc-IF8u - Manual (Page 80)

70 Compact IO ™ Universal Input Modules
Negative Decimal
Values
In two’s complement notation, the far left position is always 1 for negative
values. The equivalent decimal value of the binary number is obtained by
subtracting the value of the far left position, 32768, from the sum of the
values of the other positions. In the figure below (all positions are 1), the
value is 32767 - 32768 = -1. For example:
1111 1000 0010 0011 = (2 14 +2 13 +2 12 +2 11 +2 5 +2 1 +2 0 ) - 2 15 =
(16384+8192+4096+2048+32+2+1) - 32768 = 30755 - 32768 = -2013