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CBD [n]
Curve buffer define for Standard Mode Buffer
Defines which data outputs are stored in the standard curve buffer when subsequent
TD (take data), TDT (take data triggered) or TDC (take data continuously)
commands are issued. Up to 17 (or 22 in dual reference and dual harmonic modes)
curves, or outputs, may be acquired, as specified by the CBD parameter.
The CBD parameter is an integer between 1 and 131,071, being the decimal
equivalent of a 17-bit binary word. In either of the dual reference modes, it is an
integer between 1 and 4,194,303, being the decimal equivalent of a 22-bit binary
number. When a given bit is asserted, the corresponding output is selected for
storage. When a bit is negated, the output is not stored. The bit function and range
for each output are shown in the table below:
Bit
Decimal value Output and range
0*
1
1*
2
2*
4
3*
8
4
16
5*
32
6*
64
7*
128
8*
256
9*
512
10*
1024
11*
2048
12*
4096
13*
8192
14
16384
15
32768
16
65536
Dual modes only:-
17*
131072
18*
262144
19*
524288
20*
1048576
21
2097152
100,000 points are available for data storage in the standard curve buffer mode,,
shared equally between the specified curves. For example, if 16 outputs are stored
then the maximum number of storage points would be 6250 (i.e. 100000/16). The
only exception to this rule is that the Frequency curve (curves 15 and 16) occupies
the equivalent of any two other curves. The LEN command sets the actual curve
length, which cannot therefore be longer than 100000 divided by the number of
curves selected. If more curves are requested than can be stored with the current
buffer length, then the buffer length will be automatically reduced. Its actual length
can of course be determined by sending the LEN command without a parameter.
The reason why bit 4 and, for dual reference modes, bit 21, which store both the
sensitivity and the IMODE setting, are needed, is to allow the instrument to transfer
Chapter 6, COMPUTER OPERATION
X Output (±10000 FS)
Y Output (±10000 FS)
Magnitude Output (0 to +10000 FS)
Phase (±18000 = ±180°)
Sensitivity setting (1 to 27) + IMODE (0, 1, 2, 3 =
0, 32, 64, 128)
Noise (0 to +10000 FS)
Ratio (±10000 FS)
Log ratio (-3000 to +2000)
ADC1 (±10000 = ±10.0 V)
ADC2 (±10000 = ±10.0 V)
ADC3 (±10000 = ±10.0 V)
ADC4 (±10000 = ±10.0 V)
DAC1 (±10000 = ±10.0 V)
DAC2 (±10000 = ±10.0 V)
EVENT variable (0 to 32767)
Reference Frequency bits 0 to 15 (millihertz)
Reference frequency bits 16 to 31 (millihertz)
X
Output (±10000 FS)
2
Y
Output (±10000 FS)
2
Magnitude2 Output (0 to +10000 FS)
Phase
Output (±18000 = ±180°)
2
Sensitivity
setting (1 to 27) + IMODE
2
(0, 1, 2 = 0, 32, 64)
6-27
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