Ametek 7124 Instruction Manual page 172

Chapter 6, COMPUTER OPERATION
LEN [n]
NC
STR [n]
TD
6-26
Dual modes only:-
Bit Decimal value
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
the acquired curves to the computer in floating point mode. Without this information,
the unit would not be able to determine the correct calibration to apply.
Note that the CBD command directly determines the allowable parameters for the
DC, DCB and DCT commands. It also interacts with the LEN command and affects
the values reported by the M command.
Since the reference frequency requires 32-bit wide data points, it occupies two curve
positions. For ease of use, if bit 15 is selected for storage then bit 16 will be
automatically selected as well, and vice-versa.
NOTE: At least one of the curves selected for storage in the curve buffer must be
chosen from those marked with an asterisk(*) in the above table.
Curve length control
The value of n sets the curve buffer length in effect for data acquisition. In fast curve
buffer mode the maximum allowed value is 100,000; in standard mode it depends on
the number of curves requested using the CBD command, and a parameter error
results if the value given is too large. For this reason, in standard mode if the number
of points is to be increased and the number of curves to be stored is to be reduced
using the CBD command, then the CBD command should be issued first.
New curve
Initializes the curve storage memory and status variables. All record of previously
taken curves is removed.
Storage interval control
Sets the time interval between successive points being acquired into the curve buffer.
n specifies the time interval in microseconds with a resolution of 1 µs. In fast curve
buffer mode, the shortest time that can be specified is 1 µs; in standard mode it is
1000 µs, or 1 ms
Take data
Initiates data acquisition. Acquisition starts at the current position in the curve buffer
and continues at the rate set by the STR command until the buffer is full. If an
Output and range
X Output (±10000 FS)
2
Y Output (±10000 FS)
2
Magnitude2 Output (0 to +10000 FS)
Phase Output (±18000 = ±180°)
2
Sensitivity setting (3 to 27) + IMODE
2
(0, 1, 2 = 0, 32, 64)