Chapter 6, COMPUTER OPERATION 
6-11 
Note that the IMODE command takes precedence over the VMODE command. 
DEMOD2SRC [n] Second stage demodulator signal source 
In the dual reference mode, the value of n sets the source of the signal for the second 
stage demodulators according to the following table: 
n  Signal source 
0  Main signal channel ADC (i.e. both demodulators are fed the same signal) 
1  ADC1 - rear panel auxiliary ADC input 
2  Demodulator 1 X channel output - this is the Tandem demodulation mode 
FLOAT [n]  Input connector shield float/ground control 
n  Selection 
0  Ground 
1  Float (connected to ground via a 1 k resistor) 
FET [n] ]    FET input selection 
The value of n controls the input device used at the signal input according to the 
following table: 
n  Input device 
0  Bipolar  
1  FET 
DCCOUPLE [n]  Input coupling control 
The value of n sets the input coupling mode according to the following table: 
n  Coupling mode 
0  AC coupled 
1  DC coupled 
SEN [n] 
SEN.  Full-scale sensitivity control 
The value of n sets the full-scale sensitivity according to the following table, 
depending on the setting of the IMODE control: 
n      full-scale sensitivity 
    IMODE=0  IMODE=1  IMODE=2 
1    2 nV  2 fA  n/a 
2    5 nV  5 fA  n/a 
3    10 nV  10 fA  n/a 
4    20 nV  20 fA  n/a 
5    50 nV  50 fA  n/a 
6    100 nV  100 fA  n/a 
7    200 nV  200 fA  2 fA 
8    500 nV  500 fA  5 fA 
9    1 µV  1 pA  10 fA 
10    2 µV  2 pA  20 fA 
11    5 µV  5 pA  50 fA 
12    10 µV  10 pA  100 fA 
13    20 µV  20 pA  200 fA 
14    50 µV  50 pA  500 fA 
15    100 µV  100 pA  1 pA 
16    200 µV  200 pA  2 pA