Keithley 2520, User Manual, Page: 164 / 329

Model 2520 User’s Manual Status Structure 11-5
Programming and reading registers
Programming enable registers
The only registers that can be programmed by the user are the enable registers. All other
registers in the status structure are read-only registers. The following explains how to
ascertain the parameter values for the various commands used to program enable registers.
The actual commands are covered later in this section (
Table 11-3 and Table 11-6 ).
A command to program an event enable register is sent with a parameter value that deter-
mines the desired state (0 or 1) of each bit in the appropriate register. An enable register
can be programmed using any of the following data formats for the parameter value:
binary, decimal, hexadecimal, or octal.
The bit positions of the register () indicate the binary parameter value. For example, if you
wish to sets bits B4, B3, and B1, the binary value would be 11010 (where B4=1, B3=1,
B1=1, and all other bits are 0). When you use one of the other formats, convert the binary
number to its decimal, hexadecimal, or octal equivalent:
Binary 11010 = Decimal 26 = Hexadecimal 1A = Octal 32
Note that Figure 11-2 includes the decimal weight for each register bit. To set bits B4, B3,
and B1, the decimal parameter value would be the sum of the decimal weights for those
bits (16+8+2 = 26).
Figure 11-2
16-bit status register
(2 7 ) (2 6 ) (2 5 ) (2 4 ) (2 3 )
(2 2 )
(2 1 ) (2 0 )
(2 15 ) (2 14 ) (2 13 ) (2 12 ) (2 11 ) (2 10 ) (2 9 ) (2 8 )
Bit Position
Binary Value
Decimal
Weights
B7 B6 B5 B4 B3 B2 B1 B0
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
128 64 32 16 8 4 2 1
B15 B14 B13 B12 B11 B10 B9 B8
32768
16384 8192 4096 2048 1024 512 256
0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1
Bit Position
Binary Value
Decimal
Weights
B. Bits 8 through 15
A. Bits 0 through 7