Keithley 2001 User Manual

IEEE-488 Reference
4-134
Query :REFerence? Query programmed reference value
:REFerence? DEFault Query *RST default reference value
:REFerence? MINimum Query lowest allowable reference value
:REFerence? MAXimum Query largest allowable reference value
Short-form formats: :curr:ac:ref? :curr[:dc]:ref?
:curr:ac:ref? xxx :curr[:dc]:ref? xxx
:volt:ac:ref? :volt[:dc]:ref?
:volt:ac:ref? xxx :volt[:dc]:ref? xxx
:res:ref? :fres:ref?
:fres:ref? xxx :fres:ref? xxx
:freq:ref? :temp:ref?
:freq:ref? xxx :temp:ref? xxx
where; xxx = def, min or max
Response message: -1100 to +3310
Description These commands are used to establish a reference value for the specified function. When Refer-
ence is enabled (see :REFerence:STATe), the result (X) will be the algebraic difference between
the input signal and the reference value:
X = Input signal - Reference
Note that the result (X) is the value that is used for the math calculation (see :CALCulate1 sub-
system). If the Reference is zero or disabled, then the normal reading is used for the math cal-
culation.
The reference value is not scaled according to what range the instrument is on. For example, a
reference value of 0.1 on DCI is 100mA on all the DC current ranges. A reference value cannot
cause the display to overrange. For example, the result of a 2A reference can be displayed on
any range as long as the input signal does not exceed the selected range. For example, assume a
100mA signal is referenced to 2A. The -1.9A result (100mA - 2A = -1.9A) will be displayed on
the 200mA range as follows:
-1.9000e+03mAAC
Note that the 4½ digit reading is in exponent form and reads as:
-1.9000 × 10
3
mA AC which equals -1.9A AC.
From the front panel, a reference is set using the REL feature.
The :REFerence <n> command is coupled to the :ACQuire command. The last command sent
(:REFerence <n> or :ACQuire) will establish the reference. When a reference is set using the
:REFerence <n> command, the :REFerence? query command will return the value sent with
the :REFerence <n> command. Conversely, when a reference is set using the :ACQuire com-
mand, the :REFerence? query command will return the acquired reference value.
A negative reference value will automatically be changed to zero when units are changed from
volts to dB or dBm.

Keithley 2001 Specifications

General

Model	2001
Category	Multimeter
Manufacturer	Keithley
Type	Digital Multimeter
Digits of Resolution	7.5
DC Voltage Range	100 mV to 1000 V
AC Voltage Range	100 mV to 750 V
Frequency Range	3 Hz to 500 kHz
Connectivity	GPIB, RS-232
Display	VFD
Resistance Accuracy	0.008% + 2.0 mΩ
Frequency Accuracy	±0.01%
DC Current Range	10 μA to 3 A
AC Current Range	10 μA to 3 A
Power Supply	100 V to 240 V AC, 45 Hz to 66 Hz