Ametek 7280 Instruction Manual page 201

EX [n] Output expansion control
n Expand mode
0 Off
1 Expand X
2 Expand Y
3 Expand X and Y
FASTMODE [n] Analog Output Mode Control
The value of n sets the fast analog output mode control according to the following
table:
n Function
0 Fast mode off
1 Fast mode on
When the fast analog output mode is turned on, the available settings for the
CH1/CH2 analog output controls are restricted, and hence affect the allowable
parameter range for CH1 and CH2 commands. It also restricts the available range of
output filter slope settings, limits the full-scale sensitivity to a maximum of 100 µV
and restricts the range of AC Gain settings if the AC Gain Automatic control is
turned off. The effect is that the instrument's dynamic reserve is limited to a
maximum value of 15 dB. Also, in this mode the minimum time per point for the
oscillator frequency or amplitude sweeps is limited to 140 ms per point.
When fast mode is turned off, the output filter time constant is restricted to values of
500 µs and longer, but the other restrictions on output filter slope, sensitivity and AC
gain are removed. In this mode the minimum time per point for the oscillator
frequency or amplitude sweeps is 1 ms per point.
FLOAT [n] Input connector shield float/ground control
n Selection
0 Ground
1 Float (connected to ground via a 1 kΩ resistor)
FRQ[.] Reference frequency meter
If the lock-in amplifier is in the external reference source modes, the FRQ command
causes the lock-in amplifier to respond with 0 if the reference channel is unlocked, or
with the reference input frequency if it is locked.
If the lock-in amplifier is in the internal reference source mode, it responds with the
frequency of the internal oscillator.
In fixed point mode the frequency is in mHz, and in floating point mode the
frequency is in Hz.
FSTART[.] [n] Oscillator frequency sweep start frequency
Sets the start frequency for a subsequent sweep of the internal oscillator frequency, in
the range 0 to 2.000 MHz.
In fixed point mode, n is in millihertz, and in floating point mode n is in hertz.
Appendix F, ALPHABETICAL LISTING OF COMMANDS
F-9