User manual
IEEE-488 Reference
4-130 2001-900-01 Rev. K / August 2010
Defaults Power-up Saved power-on setup
*RST 0 (all functions)
:SYSTem:PRESet 0 (all functions)
Query :REFerence? Query programmed reference value
:REFerence? DEFault Query *RST default reference value
:REFerence? MINimumQuery lowest allowable reference value
:REFerence? MAXimumQuery 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 Ref-
erence is enabled (see :REFerence:STATe), the result (X) will be the algebraic difference be-
tween 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 4H 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.