Keithley 6487 Reference Manual

Model 6487 Reference Manual DDC Emulation Commands C-13
Figure C-2
U1 error status word
Figure C-3
U9 voltage source status word
Status byte format
The status byte contains information relating to data and error conditions within the instru-
ment. When a particular bit is set, certain conditions are present. Table C-2 lists the mean-
ings of the various bits and Figure C-4 shows the general format of the status byte, which
is obtained by using the SPE, SPD polling sequence.
If the status byte is read when no SRQ was generated by the Model 6487 (bit 6 is clear),
the current status of the instrument will be read. For example, if a reading was done, bit 3
would be set.
SRQ is enabled by setting the corresponding bit with the SRQ mask using the M com-
mand (see Table C-1). The Model 6487 may be programmed to generate an SRQ for more
than one condition simultaneously, simply by adding up the command option values.
487 1/0 1/0 1/0 1/0 1/0 1/0 1/0 1/0 1/0 1/0 1/0 1/0 1/0
1 = E PROM
Cal Constants
2
1 = E PROM Defaults
2
1= Calibration
1= Zero Check
1= No Remote
1 = Self-Test
1 = Trigger Overrun
1 = Conflict
1 = Cal Locked
1 = V-Source
1 = V-Source Conflict
1 = IDDC
1 = IDDCO
487 1/0 1/0
1= Interlock Open
1 = Current Limit

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%