Keithley 2182, Quick Reference Manual, Page: 21 / 30

Quick Reference Guide 15
• The STD DEV value is the standard deviation of the buffered readings. The equation
used to calculate the standard deviation is:
where: Xi is a stored reading.
n is the number of stored readings.
NOTE The Model 2182 uses IEEE-754 floating point format for math calculations.
Remote buffer programming
SCPI commands
SCPI commands to configure and control the buffer and buffer statistics are listed in Table 7.
Table 7
Buffer SCPI commands
Command Description
:TRACe:CLEar Clear readings from buffer.
:TRACe FREE? Query bytes available and bytes in use.
:TRACe:POINts <n> Specify number of readings to store: 2 to 1024.
:TRACe:FEED <name> Select source of readings: SENSe, CALCulate, or
NONE.
:TRACe:FEED:CONTrol <name> Select buffer control mode: NEVer or NEXT.
:TRACe:DATA? Read all readings in buffer.
:CALCulate2:FORMat <name>
Select buffer statistic: MINimum, MAXimum,
MEAN, SDEViation, or NONE.
:CALCulate2:STATe <b> Enable or disable statistic calculation
:CALCulate2:IMMediate Recalculate raw input data in buffer.
:CALCulate2:IMMediate? Perform calculation and read result.
:CALCulate2:DATA? Read result of statistic calculation.
X
2
i
i 1 =
n
∑
1
n
--- X
i
i 1 =
n
∑
 
 
 
 
2
 
 
 
 
–
n-1
--------------------------------------------------------------
y =