Keithley 6487 Reference Manual

Model 6487 Reference Manual DDC Emulation Commands C-15
Voltage Source Error (B7) — Set if the voltage source has reached current limit or if the
interlock is tripped. Cleared by reading U9 status after correcting the voltage source error
(see Figure C-3).
klqb Once the Model 6487 has generated an SRQ, its status byte must be read to
clear the SRQ line. Otherwise, the instrument will continuously assert SRQ.
Figure C-4
Status byte format
Table C-2
Status byte and SRQ mask interpretation
Bit
Decimal
Weighting
Description
0 (LSB) 1 Reading Overflow
1 2 Data Store Full
2 4 Data Store 1/2 Full
3 8 Reading done
4 16 Ready
532 Error
6 64 RQS (Request for Service)*
7 128 Voltage Source Error
* Status byte only
MSB B7 B6 B5 B4 B3 B2 B1 B0 LSB
Reading
Done
Data
Store
Full
Reading
OverflowErrorRQS*
Data
Store
1/2 Full
Ready
V-source
Error
* Status bye only

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%