Ametek 7230 Instruction Manual page 112

Chapter 6, COMPUTER OPERATION
LEN [n]
NC
STR [n]
TD
TDT n
6-26
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
oscillator frequency and/or amplitude sweep has been defined and linked to the curve
buffer using the SWEEP command with a parameter of 9, 10 or 11, then this sweep
will be started as well.
Take data triggered
Sets the instrument so that data acquisition is initiated on receipt of various trigger
conditions at the TRIG connector on the rear panel. If an oscillator frequency and/or
amplitude sweep has been defined and linked to the curve buffer using the SWEEP
command with a parameter of 9, 10 or 11, then this sweep will be started as well.
There are two basic triggers. The Acquisition trigger is a "per curve" (start) or "per
point" (sample) trigger and can be active on either the rising or falling edge. The
Stop trigger sets the condition by which acquisition finishes. In normal operation this
is simply when the number of points specified by the LEN command parameter have
been acquired, but it is also possible to leave acquisition running until an HC
command is sent or until either a rising or falling edge occurs at the trigger input.
The trigger modes, set by the value of n, are as follows: