Decimal representation of a bit pattern
The STB and ESR registers contain 8 bits, the SCPI registers contain 16 bits. The contents of a status register are specified and transferred as a single decimal number. Each bit is assigned a weighted value. The decimal number is calculated as the sum of the weighted values of all bits in the register that are set to 1.
Bits | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | ... |
Weight | 1 | 2 | 4 | 8 | 16 | 32 | 64 | 128 | ... |
Example
The decimal value 40 = 32 + 8 indicates that bits no. 3 and 5 in the status register are set.