Ametek 7280 Instruction Manual page 162

Chapter 6, COMPUTER OPERATION
TDC
EVENT [n]
HC
M
6-28
store a complete curve or set of curves, the number of triggers applied must equal the
number of points specified by the LEN command parameter. Note that in this mode
the maximum trigger rate is 1000 Hz and the storage interval control setting has no
effect.
Take data continuously
Initiates data acquisition. Acquisition starts at the current position in the curve buffer
and continues at the rate set by the STR command until halted by an HC command.
The buffer is circular in the sense that when it has been filled, new data overwrites
earlier points.
Event marker control
During a curve acquisition, if bit 13 in the CBD command has been asserted, the
lock-in amplifier stores the value of the Event variable at each sample point. This can
be used as a marker indicating the point at which an experimental parameter was
changed. The EVENT command is used to set this variable to any value between 0
and 32767.
Halt curve acquisition
Halts curve acquisition in progress. It is effective during both single (data acquisition
initiated by TD command) and continuous (data acquisition initiated by TDC
command) curve acquisitions. The curve may be restarted by means of the TD, TDT
or TDC command, as appropriate. 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 100, then this sweep will be stopped as well.
Curve acquisition status monitor
Causes the lock-in amplifier to respond with four values that provide information
concerning data acquisition, as follows:
First value, Curve Acquisition Status: a number with five possible values, defined
by the following table:
First Value Significance
0 No curve activity in progress.
1 Acquisition via TD command in progress and running.
2 Acquisition via TDC command in progress and running.
5 Acquisition via TD command in progress but halted by HC
command.
6 Acquisition via TDC command in progress but halted by
HC command.
Second value, Number of Sweeps Acquired: This number is incremented each
time a TD is completed and each time a full cycle is completed on a TDC acquisition.
It is zeroed by the NC command and also whenever a CBD or LEN command is
applied without parameters.
Third value, Status Byte: The same as the response to the ST command. The
number returned is the decimal equivalent of the status byte and refers to the
previously applied command.