Keithley 6487 Reference Manual

Model 6487 Reference Manual DISPlay, FORMat, and SYSTem 13-5
The response to READ?, FETCh?, MEASure?, TRACe:DATA?, CALC1:DATA?,
CALC2:DATA?, or CALC3:DATA? over the GPIB can be returned in either the ASCii or
binary format. All other queries are returned in ASCii, regardless of the selected format.
Over the RS-232 interface, only the ASCII format is allowed.
klqb Regardless of which data format for output strings is selected, the instrument
will only respond to input commands using the ASCII format.
ASCII data format
The ASCII data format is in a direct readable form for the operator. Most programming
languages easily convert ASCII mantissa and exponent to other formats. However, some
speed is compromised to accommodate the conversion. Figure 13-1 shows an example
ASCII string that includes all the data elements. See :ELEMents for information on the
data elements.
Figure 13-1 also shows the byte order of the data string. Data elements not specified by the
:ELEMents command are simply not included in the string. Note that the status value is
always an integer, but it is still expressed in scientific notation.
Figure 13-1
ASCII data format
+1.040564E-06A, +2.2362990+2, +1.380000E+2, +123.4500
Reading Timestamp StatusUnits V-source

Keithley 6487 Specifications

General

Type	Picoammeter/Voltage Source
Current Measurement Range	20 fA to 20 mA
Interfaces	GPIB, RS-232
Voltage Burden	< 200 µV
Input Impedance	>10^14 Ω
Power	100 V / 120 V / 220 V / 240 V
Basic Current Measurement Accuracy	0.4%