Keithley 2001 User Manual

IEEE-488 Reference
4-19
When a message is placed in the Error Queue, the Error
Available (EAV) bit in the Status Byte Register is set. An er-
ror message is cleared from the Error/Status Queue when it
is read. The Error Queue is considered cleared when it is
empty. An empty Error Queue clears the EAV bit in the Sta-
tus Byte Register. An error message from the Error Queue is
read by sending either of the following SCPI query com-
mands and then addressing the Model 2001 to talk:
:SYSTem:ERRor?
:STATus:QUEue?
Refer to paragraphs 4.21 (:STATus:QUEue?) and 4.22
(:SYSTem:ERRor?) for complete information on reading er-
ror messages.
4.6.9 Status byte and service request (SRQ)
Service request is controlled by two 8-bit registers; the Status
Byte Register and the Service Request Enable Register. The
structure of these registers is shown in Figure 4-13.
F
igure 4-13
Status byte and service request (SRQ)
Status Summary Messages
* STB ?
Serial Poll
OSB
(B7)
RQS
(B6)
MSS
ESB
(B5)
MAV
(B4)
QSB
(B3)
EAV
(B2) (B1) (B0)
OR
* SRE
* SRE ?
Status Byte
Register
Service Request
Enable Register
OSB = Operation Summary Bit
MSS = Master Summary Status
RQS = Request for Service
ESB = Event Summary Bit
MAV = Message Available
QSB = Questionable Summary Bit
EAV = Error Available
MSB = Measurement Summary Bit
& = Logical AND
OR = Logical OR
OSB
(B7) (B6)
ESB
(B5)
MAV
(B4)
QSB
(B3)
EAV
(B2) (B1) (B0)
&
&
&
&
&
MSB
MSB
&
Service
Request
Generation
Read by Serial Poll
Read by *STB ?
Status Byte Register  The summary messages from the
status registers and queues are used to set or clear the
appropriate bits (B0, B2, B3, B4, B5 and B7) of the Status
Byte Register. These bits do not latch and their states (0 or 1)
are solely dependent on the summary messages (0 or 1). For
example, if the Standard Event Status Register is read, its
register will clear. As a result, its summary message will
reset to 0, which in turn will clear the ESB bit in the Status
Byte Register.
Bit B6 in the Status Byte Register is either:
• The Master Summary Status (MSS) bit, sent in re-
sponse to the *STB? command, indicates the status of
any set bits with corresponding enable bits set.
• The Request for Service (RQS) bit, sent in response to
a serial poll, indicates which device was requesting ser-
vice by pulling on the SRQ line.
For description of the other bits in the Status Byte Register,
refer to paragraph 4.10.14.

Keithley 2001 Specifications

General

Model	2001
Category	Multimeter
Manufacturer	Keithley
Type	Digital Multimeter
Digits of Resolution	7.5
DC Voltage Range	100 mV to 1000 V
AC Voltage Range	100 mV to 750 V
Frequency Range	3 Hz to 500 kHz
Connectivity	GPIB, RS-232
Display	VFD
Resistance Accuracy	0.008% + 2.0 mΩ
Frequency Accuracy	±0.01%
DC Current Range	10 μA to 3 A
AC Current Range	10 μA to 3 A
Power Supply	100 V to 240 V AC, 45 Hz to 66 Hz