IBM 7220 Instruction Manual page 101

HC 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 or
TDC command, as appropriate.
M 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.
Fourth value, Number of Points Acquired: This number is incremented each time a
point is taken. It is zeroed by the NC command and whenever CBD or LEN is applied
without parameters.
DC[.] n Dump acquired curve(s) to computer
In fixed point mode, causes a stored curve to be dumped via the computer interface in
decimal format.
In floating point mode the SEN curve (bit 4 in CBD) must have been stored if one or
more of the following outputs are required in order that the lock-in amplifier can
perform the necessary conversion from %FS to volts or amps: X, Y, Magnitude,
Noise.
One curve at a time is transferred. The value of n is the bit number of the required
curve, which must have been stored by the most recent CBD command. Hence n can
range from 0 to 15. If for example CBD 5 had been sent, equivalent to asserting bits
0 and 2, then the X and Magnitude outputs would be stored. The permitted values of
n would therefore be 0 and 2, so that DC 0 would transfer the X output curve and
DC 2 the Magnitude curve.
Chapter 6, COMPUTER OPERATION
6-25