Keithley 2790, Reference Manual

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Model 2790 SourceMeter
®
Switch System Reference Manual 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 11-2 and Table 11-5 ).
A command to program an event enable register is sent with a decimal parameter value
that determines the desired state (0 or 1) of each bit in the appropriate register. The bit
positions of the register (
Figure 11-2 ) indicate the binary parameter value. For example, if
you wish to set bits B4, B3, and B1, the binary value would be 11010 (where B4=1, B3=1,
B1=1, and all other bits are 0).
The binary value is then converted to its decimal equivalent:
Binary 11010 = Decimal 26
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 )
32768 16384
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
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