Ametek 7280 Instruction Manual page 197

n = 1 (i.e. CH1 output)
1
n Signal
2
0 X1 % (2.5 V FS)
n 2 (i.e. CH2output)
1
n Signal
2
10 X2 % (2.5 V FS)
CP [n] Input connector coupling mode control
The value of n sets the input coupling mode according to the following table:
n Coupling mode
0 Fast
1 Slow
DAC[.] n [n ] Auxiliary DAC output controls
1 2
The first parameter n
The value of n specifies the voltage to be output.
2
In fixed point mode it is an integer in the range -12000 to +12000, corresponding to
voltages from -12.000V to +12.000V, and in floating point mode it is in volts.
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. Similarly, if the dual reference or harmonic modes are active then the SEN2
curve (bit 21 in CBD) must have been stored in order to perform a similar conversion
from %FS to volts or amps for X2, Y2 and Magnitude2.
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 16, or 0 to 21 if a dual mode is active. 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 channel output curve and DC 2 the Magnitude curve.
NOTE: When transferring the Frequency curve, which is saved when bit 15 in the
CBD parameter is asserted, the instrument automatically reads the data for each
stored point in both frequency curves (i.e. the lower and upper 16 bits) and sends it
as a single data point.
The computer program's subroutine which reads the responses to the DC command
needs to run a program loop that continues until all the data has been transferred.
Note that when using this command with the GPIB interface the serial poll must be
used. After sending the DC command, perform repeated serial polls until bit 7 is set,
indicating that the instrument has an output waiting to be read. Then perform
repeated reads in a loop, waiting each time until bit 7 is set indicating that a new
Appendix F, ALPHABETICAL LISTING OF COMMANDS
, which specifies the DAC, is compulsory and is either 1 or 2.
1
F-5