Keithley 6485 User manual

Model 6485 Picoammeter
Instruction Manual
A GREATER MEASURE OF CONFIDENCE

Model 6485 Picoammeter
Instruction Manual
©2001, Keithley Instruments, Inc.
All rights reserved.
Cleveland, Ohio, U.S.A.
First Printing, November 2001
Document Number: 6485-901-01 Rev. A

1
Getting Started
• Introduction — Description of the Model 6485 Picoammeter.
• Overview of this manual — Provides content of this manual.
• General information — Covers general information that includes warranty infor-
mation, contact information, safety symbols and terms, inspection, and available
options and accessories.
• Features — Summarizes the features of Model 6485.
• Front and rear panel familiarization — Summarizes the controls and connectors of
the instrument as well as providing information on the front panel display.
• Power-up — Covers line power connection, line voltage setting, fuse replacement,
power line frequency, and the power-up sequence.
• Default settings — Covers the five instrument setup configurations available to the
user; three user defined, GPIB defaults, or factory defaults.
• SCPI programming — Explains how SCPI commands are presented in this man-
ual.

1-2 Getting Started Model 6485 Picoammeter Instruction Manual
Introduction
The Model 6485 is a high resolution bus-programmable (RS-232 and IEEE-488) picoam-
meter. The Model 6485 has the following current measurement ranges: 8 ranges (from
20mA down to the 2nA range, with the 2nA range having the lowest noise).
Overview of this manual
This manual describes how to connect, program, and maintain the Model 6485 Picoamme-
ter. The sections of the manual are organized as follows:
–Section 1: Getting Started
–Section 2: Measurement Concepts and Connections
–Section 3: Measurements
–Section 4: Range, Units, Digits, Rate, and Filters
–Section 5: Relative, mX+b, m/X+b (Reciprocal), and Log
–Section 6: Buffer
–Section 7: Triggering
–Section 8: Limit test
–Section 9: Remote Operation
–Section 10: Status Structure
–Section 11: Common Commands
–Section 12: SCPI Signal Oriented Measurement Commands
–Section 13: DISPlay, FORMat, and SYSTem
–Section 14: SCPI Reference Tables
–Section 15: Performance Verification
–Section 16: Calibration
–Section 17: Routine Maintenance
Appendices to this manual contain specification and also provide additional information
on specific topics. The appendices are organized as follows:
–Appendix A: Specifications
–Appendix B: Status and Error Messages
–Appendix C: Measurement Considerations
–Appendix D: DDC Emulation Commands
–Appendix E: Example Programs
–Appendix F: IEEE-488 Bus Overview
–Appendix G: IEEE-488 and SCPI Conformance Information
–Appendix H: Remote Calibration
–Appendix I: Applications Guide

Model 6485 Picoammeter Instruction Manual Getting Started 1-3
General information
Warranty information
Warranty information is located at the front of this manual. Should your Model 6485
require warranty service, contact the Keithley representative or authorized repair facility in
your area for further information. When returning the instrument for repair, be sure to fill
out and include the service form at the back of this manual to provide the repair facility
with the necessary information.
Contact information
Worldwide phone numbers are listed at the front of this manual. If you have any questions,
please contact your local Keithley representative or call one of our Application Engineers
at 1-800-348-3735 (U.S. and Canada only).
Safety symbols and terms
The following symbols and terms may be found on the instrument or used in this manual:
The symbol on an instrument indicates that the user should refer to the operating
instructions located in the manual.
The symbol on the instrument shows that high voltage may be present on the termi-
nal(s). Use standard safety precautions to avoid personal contact with these voltages.
The WARNING heading used in this manual explains dangers that might result in per-
sonal injury or death. Always read the associated information very carefully before per-
forming the indicated procedure.
The CAUTION heading used in this manual explains hazards that could damage the
instrument. Such damage may invalidate the warranty.
Unpacking and inspection
Inspection for damage
The Model 6485 was carefully inspected electrically and mechanically before shipment.
After unpacking all items from the shipping carton, check for any obvious signs of physi-
cal damage that may have occurred during transit. (There may be a protective film over the
display lens, which can be removed.) Report any damage to the shipping agent immedi-
ately. Save the original packing carton for possible future shipment. Before removing the
6485 Picoammeter from the bag, observe the precautions on handling discussed below.
!

1-4 Getting Started Model 6485 Picoammeter Instruction Manual
Handling precautions
• Always grasp the 6485 by the covers.
• After removing the 6485 from its anti-static bag, inspect it for any obvious signs of
physical damage. Report any such damage to the shipping agent immediately.
• When the 6485 is not installed and connected, keep the unit in its anti-static bag,
and store it in the original packing carton.
Package content
The following items are included with every Model 6485 order:
• Model 6485 Picoammeter with line cord.
• Low Noise Cable with Male BNC on both ends (Model 4801).
• Protective BNC Shield/Cap (CAP-18).
• Banana lead to screw terminal adapter (Model CA-186-1B). (Referred to as ground
link throughout this manual.)
• Accessories as ordered.
• Certificate of calibration.
• Model 6485 User Manual (P/N LCHR-950-01).
• Manual Addenda (pertains to any improvements or changes concerning the instru-
ment or manual).
Options and accessories
Input cables, connectors, and adapters
Model 4801 Input Cable — This 4 ft (1.2m) low-noise coax cable is terminated with male
BNC connectors on each end. (One Model 4801 is included with every order).
Model 4802-10 — This 10 ft (3m) low-noise coax cable is terminated at one end with a
male BNC connector (the other end is unterminated).
Model 4803 Low Noise Cable Kit — This cable kit includes:
– 15m (50 ft) of low noise coax cable
– 10 male BNC connectors
– 5 female BNC chassis-mount connectors
Model 7078-TRX-BNC adapter — 3-slot male triax to female BNC
Model 8607 — Banana cable set (1m).
CA-186-1B — Banana lead to screw terminal adapter (one model CA-186-1B is included
with every order).

Model 6485 Picoammeter Instruction Manual Getting Started 1-5
CAP-18 — Protective shield/cap for BNC connectors (one model CAP-18 is included
with every order).
CS-565 barrel adapter — This is a barrel adapter that allows you to connect two BNC
cables together. Both ends of the adapter are terminated with 2-lug female BNC connec-
tors.
GPIB and trigger link cables and adapters
Models 7007-1 and 7007-2 shielded GPIB cables — Connect Model 6485 to the GPIB
bus using shielded cables and connectors to reduce electromagnetic interference (EMI).
Model 7007-1 is lm long; Model 7007-2 is 2m long.
Models 8501-1 and 8501-2 trigger link cables — Connect Model 6485 to other instru-
ments with Trigger Link connectors (e.g., Model 7001 Switch System). Model 8501-1 is
lm long; Model 8501-2 is 2m long.
Model 8502 trigger link adapter — Lets you connect any of the six trigger link lines of
Model 6485 to instruments that use the standard BNC trigger connectors.
Model 8503 DIN to BNC trigger cable — Lets you connect trigger link lines one (Volt-
meter Complete) and two (External Trigger) of Model 6485 to instruments that use BNC
trigger connectors. Model 8503 is lm long.
Rack mount kits
Model 4288-1 single fixed rack mount kit — Mounts a single Model 6485 in a standard
19-inch rack.
Model 4288-2 side-by-side rack mount kit — Mounts two instruments (Models 182,
428, 486, 487, 2000, 2001, 2002, 2010, 2400, 2410, 2420, 2430, 6430, 6485, 6517 A,
7001) side-by-side in a standard 19-inch rack.
Model 4288-4 side-by-side rack mount kit — Mounts Model 6485 and a 5.25-inch
instrument (Models 195A, 196, 220, 224, 230, 263, 595, 614, 617, 705, 740, 775A, 6512)
side-by-side in a standard 19-inch rack.
Carrying case
Model 1050 padded carrying case — A carrying case for Model 6485. Includes handles
and shoulder strap.
Instruction Manual
If an additional Model 6485 manual is required, order the manual package. The Keithley
part number for the Instruction manual is 6485-901-010. The manual package includes an
instruction manual and any pertinent addenda.

1-6 Getting Started Model 6485 Picoammeter Instruction Manual
Additional references
While reading this document, you may find it helpful to consult the following documenta-
tion for reference:
Low Level Measurements handbook — Keithley’s guide for effective low current, low
voltage, and high impedance measurements.
Features
The Model 6485 is a high-performance picoammeter capable of measuring current.
Section 2 contains details on its measurement capabilities (“Measurement overview,” page
4-2). Features of Model 6485 Picoammeter include:
Setup storage — Five instrument setups (three user, GPIB defaults, and factory defaults)
can be saved and recalled. See “Front panel setup operation,” page 1-15.
mX+b, m/X+b (reciprocal—for resistance calculations), and log10 — These calculations
provide mathematical manipulation of readings (Section 5).
Relative — Null offsets or establish baseline values (Section 5).
Buffer — Store up to 2500 readings in the internal buffer (Section 6).
Limits — Set up to two stages of high and low reading limits to test devices (Section 8).
Remote interface — Model 6485 can be controlled using the IEEE-488 interface (GPIB)
or the RS-232 interface (Section 9).
GPIB programming language — When using the GPIB, the instrument can be pro-
grammed using the SCPI or DDC programming language (Section 9).
Front and rear panel familiarization
Front panel summary
The front panel of Model 6485 is shown in Figure 1-1.

Model 6485 Picoammeter Instruction Manual Getting Started 1-7
Figure 1-1
Front panel
NOTE To modify a key’s properties, press the CONFIG / LOCAL key (see Special keys
and power switch) and then the key. Not all keys have configurable properties.
1 Special keys and power switch
CONFIG/ When in Local operation, use to configure properties of the next button pressed.
LOCAL When in Remote operation (REM annunciator lit), cancels GPIB remote mode.
MENU Provides access to menu.
POWER Power switch. In position turns 6485 on (I), out position turns it off (O).
2 Function keys
MEDN Use to control and modify properties of the median filter.
AVG Use to control and modify properties of the digital filter.
MX+B Use to perform and configure properties of the mX+b math function.
M/X+B Use to perform and configure properties of the m/X+b math function.
LOG Use to convert output / display to log10 (on / off).
REL Use to control and configure properties of the rel(ative) function.
ZCHK Use to perform a Zero Check function.
ZCOR Use to control Zero Correct function (on / off).
3 Operation keys
COMM Use to control and modify communication properties (GPIB or RS-232).
DISP Use to turn display on/off.
TRIG Trigger measurement(s). Takes 6485 out of idle state. Use also to configure trigger
properties.
6485
PICOAMMETER
RANGE
AUTO
CONFIG/
LOCAL
MENU
POWER
RANGE
SHIFT
CH1REM
TALK
LSTN
SRQ
STAT
REL FILT
4W
BUFFER
MATH
REAR
SCAN
TIMER
STEP CH2 CH3 CH4 CH5 CH6 CH7 CH8 CH9 CH10
HOLD TRIG FAST MED SLOW AUTO ERR
EXIT ENTER
HALT RATEDIGITS
STORE RECALL
MEDN
5
1
24
6
A G MX+B M/X+B LOG REL ZCHK ZCOR
COMM DISP TRIG
LIMIT AZERO
SAVE SETUP
3

1-8 Getting Started Model 6485 Picoammeter Instruction Manual
HALT Stops measurement process. Puts 6485 in idle state.
DIGITS Use to set display resolution.
RATE Use to select measurement rate.
andUse to control cursor position for making selections or editing values.
SAVE Use to save present setup to a memory location.
SETUP Use to restore setup to either GPIB or factory defaults, or to a user memory location.
Also use to modify properties of power on defaults to either GPIB or factory defaults,
or to a user memory location.
STORE Use to start buffer and modify the number of readings to store.
RECALL Use to display stored readings (including maximum, minimum, peak-to-peak, aver-
age, and standard deviation). The and range keys scroll through the buffer, and
the or key toggles between reading number, reading, and timestamp.
LIMIT Use to perform and create limit tests.
AZERO Use to control auto zero function (on / off).
EXIT Use to cancel selection and move back to measurement display.
ENTER Use to accept selection and move to next choice or back to measurement display.
4 Range keys
Use to select the next higher measurement range. Also use to modify the upper auto-
range limit.
Use to select the next lower measurement range. Also use to modify the lower auto-
range limit.
AUTO Enables/disables autorange.
5 Display annunciators
* (asterisk) Readings being stored in buffer.
(more) Indicates additional selections are available.
AUTO Autorange enabled.
BUFFER Recalling readings stored in buffer.
ERR Questionable reading, or invalid cal step.
FAST Fast (0.1 PLC) reading rate selected.
FILT MEDIAN and/or AVERAGE filter enabled.
LSTN Instrument addressed to listen over GPIB.
MATH mX+b, m/X+b, or log10 calculation enabled.
MED Medium (1 PLC) reading rate selected.
REL Relative enabled for present measurement function.
REM Instrument in GPIB remote mode.
SLOW Slow reading rate selected; 6 PLC for 60Hz or 5 PLC for 50Hz.
SRQ Service request over GPIB.
STAT Displaying buffer statistics.
TALK Instrument addressed to talk over GPIB bus.
TIMER Timer controlled triggering in use.
TRIG External triggering (GPIB or trigger link) selected.
6 Handle
Pull out and rotate to desired position.
Rear panel summary
The rear panel of Model 6485 is shown in Figure 1-2.

Model 6485 Picoammeter Instruction Manual Getting Started 1-9
Figure 1-2
Rear panel
1 INPUT
This standard female BNC connector is used to connect the signal to be measured to the input of the
Model 6485. Mates to a BNC cable.
2 CHASSIS
This screw terminal is used to connect COMMON to CHASSIS ground via the ground link connector.
3 COMMON
This standard banana connector can be used as input LO or as the common for the ANALOG OUT.
Also can be used as a ground link.
4 ANALOG OUT
This standard banana connector provides a scaled, inverting output (inverting 2V full scale on all
ranges).
5 TRIGGER LINK
Eight-pin micro-DIN connector for sending and receiving trigger pulses among connected instru-
ments. Use a trigger link cable or adapter, such as Models 8501-1, 8501-2, 8502 and 8503.
120
FUSE LINE
630mA
LINE RATING
50, 60Hz
30 VA
T
(SB)
100 VAC
120 VAC
315mAT
(SB)
220 VAC
240 VAC
!
INPUT
(CHANGE IEEE ADDRESS
WITH FRONT PANEL MENU)
IEEE-488
CAT I
TRIGGER LINK RS-232
MADE IN
U.S.A.
220V PK
ANALOG OUT
13 45 67
8
2

1-10 Getting Started Model 6485 Picoammeter Instruction Manual
6 RS-232
Female DB-9 connector for RS-232 operation. Use a straight-through (not null modem) DB-9 shielded
cable.
7 IEEE-488
Connector for IEEE-488 (GPIB) operation. Use a shielded cable, such as Models
7007-1 and 7007-2.
8 Power module
Contains the AC line receptacle and power line fuse. The instrument can be configured for line volt-
ages of 115V and 230VAC (nominal) at line frequencies of 50 or 60Hz automatically and over the bus.
Changing line voltages requires changing fuses.
Analog output
The Model 6485 has an analog output on the rear panel. The ANALOG OUT provides a
scaled, inverting ±2V output. A full-scale reading corresponds to ±2V output.
WARNING The maximum safe voltage between picoammeter LO and chassis
ground (common mode voltage) is 42V. The Model 6485 does not inter-
nally limit the LO to chassis voltage. Exceeding 42V can create a shock
hazard.
CAUTION The LO to chassis breakdown voltage is 500V. Exceeding this voltage
may cause damage to the instrument.
Connecting COMMON or ANALOG OUT to earth while floating the
input may damage the instrument.
Connections for using this output are shown in Figure 1-3. For a full-scale input (i.e. 2mA
on the 2mA range), the output will be -2V. Example analog outputs are listed in Table 1-1.
The 2V analog output signal is not corrected during calibration. Gain errors of up to 3%
may appear at this output, depending on range.
The output impedance is 1kΩ. To minimize the effects of loading, the input impedance of
the device connected to the ANALOG OUT should be as high as possible. For example,
for a device that has an input impedance of 10MΩ, the error due to loading will be approx-
imately 0.01%. High capacitance connected to the analog output will increase the rise
time.
Rel and the result of mX+b, m/X+b, or LOG have no affect on the analog output. The 2V
analog output is scaled only to the actual input.

Model 6485 Picoammeter Instruction Manual Getting Started 1-11
Figure 1-3
Typical analog output connections
Table 1-1
Example 2V analog output values
Range Applied
signal
Analog output
value (nominal)*
20nA 10.5nA -1.05V
2mA -1.65mA 1.65V
* Output values are within ±3% of nominal value.
Fuse*
Test Lead
*Poly fuse (Auto resetting)
120
FUSE LINE
630mA
LINE RATING
50, 60Hz
30 VA
T
(SB)
100 VAC
120 VAC
315mAT
(SB)
220 VAC
240 VAC
!
INPUT
(CHANGE IEEE ADDRESS
WITH FRONT PANEL MENU)
IEEE-488
CAT I
TRIGGER LINK RS-232
MADE IN
U.S.A.
220V PK
ANALOG OUT
Model 6485 Rear Panel
RL= Input Resistance of
measuring device
Input from
Prescaler
COM
S
+
-
S
0.1Ω
1kΩ
Measuring Device
(i.e. Chart recorder)
Analog Output
A. Connections
LO
HI
B. Equivalent Circuit
Model 6485

1-12 Getting Started Model 6485 Picoammeter Instruction Manual
Display
Readings can be displayed in engineering units or scientific notation (see “Units,” page 4-
3for details). Annunciators indicate various states of operation. See “Front panel sum-
mary,” page 1-6 for a complete listing of display annunciators.
The Display and Keys Test allows you to test display digit segments and annunciators, and
check the functionality of front panel keys. These tests are accessed through the MENU.
To access these tests:
1. While in reading mode, press MENU. If not in reading mode, press EXIT first then
press MENU.
2. Scroll using range keys (or ) to the TEST sub-menu (TEST will be flashing).
3. Press ENTER (or ) to select TEST (DISP will be flashing).
4. Scroll using range keys (or ) to desired test (DISPlay or KEY).
Refer to Section 13 for additional details.
Status and error messages
Status and error messages are displayed momentarily. During operation and programming,
you will encounter a number of front panel messages. Typical messages are either of status
or error variety, as listed in Appendix B.
Messages, both status and error, are held in queues. For information on retrieving mes-
sages from queues, see Section 10.
Power-up
Line power connection
Follow the procedure below to connect the Model 6485 to line power and turn on the
instrument.
1. Check to see that the line voltage indicated in the window of the fuse holder assem-
bly (Figure 1-2) is correct for the operating voltage in your area. If not, refer to the
procedure in Section 17 for setting line voltage and fuse replacement.
CAUTION Operating the instrument on an incorrect line voltage may cause dam-
age to the instrument, possibly voiding the warranty.
2. Before plugging in the power cord, make sure that the front panel power switch is
in the off (O) position.
3. Connect the female end of the supplied power cord to the AC receptacle on the rear
panel. Connect the other end of the power cord to a grounded AC outlet.

Model 6485 Picoammeter Instruction Manual Getting Started 1-13
WARNING The power cord supplied with the Model 6485 contains a separate
ground wire for use with grounded outlets. When proper connections
are made, instrument chassis is connected to power line ground
through the ground wire in the power cord. Failure to use a grounded
outlet may result in personal injury or death due to electric shock.
4. Turn on the instrument by pressing the front panel power switch to the on (I) posi-
tion.
Line frequency
The Model 6485 operates at line frequencies of 50 or 60Hz. When auto detect is enabled
(factory default), line frequencies are automatically sensed and set accordingly, therefore
there are no switches to set. Use the :SYSTem:LFRequency? command (query) to read the
line frequency. The factory default setting is auto detect enabled.
If the power line is noisy, auto detect may not be able to lock in on a frequency. If this
occurs, set the frequency manually. This may be accomplished using the front panel (see
the following procedure) or over the bus. Refer to Table 1-2 for commands.
Front panel procedure
1. Press MENU.
2. Scroll to the LFREQ: menu item using the and range keys. The present setting
is displayed.
3. Press the range key. The present setting is now highlighted.
4. Use the and range keys to scroll to the desired menu item:
AUTOXX, 50, or 60
5. Press ENTER.
NOTE In the setting of AUTOXX, XX is the currently detected frequency.
SCPI programming —line frequency
Table 1-2
SCPI commands — line frequency
Command Description
SYSTem
:LFRequency <freq>
:AUTO <b>
:AUTO?
:LFRequency?
SYSTem Subsystem:
Set power line frequency (in Hz) to 50 or 60.
Turn automatic frequency detection ON or OFF.
Read the present automatic detected line frequency
state (1 = on, 0 = off).
Read present line frequency setting.

1-14 Getting Started Model 6485 Picoammeter Instruction Manual
Power-up sequence
The following power-up sequence occurs when the Model 6485 is turned on:
1. The Model 6485 performs self-tests on its EPROM and RAM with all digits and
annunciators turned on. If a failure is detected, the instrument momentarily dis-
plays an error message and the ERR annunciator turns on. Error messages are
listed in Appendix B.
NOTE If a problem develops while the instrument is under warranty, return it to
Keithley Instruments Inc., for repair.
2. If the instrument passes the self-tests, the firmware revision levels are displayed.
For example:
6485 B01
3. After the firmware revision levels are displayed, the detected line frequency is dis-
played.
For example:
FREQ: 60Hz
4. After the detected line frequency is displayed, information on the selected remote
interface is displayed:
a. GPIB — If the GPIB is the selected interface, the instrument will display the
selected language (SCPI or DDC) and primary address.
Examples:
SCPI ADDR: 14
DDC ADDR: 14
b. RS-232 — If RS-232 is the selected interface, the instrument will display the baud
rate setting. For example:
RS-232: 9600b
5. If the FACTory setup is selected as the power on setup, the unit is placed in the
default reading mode after the communication information is displayed. If a setup
other than FACTory is selected, the configured setup will be displayed. For exam-
ple, if the USR1 setup (User Setup #1) is selected:
USING USR1
NOTE To configure power-on set up:
-Display PWR-ON: menu (press CONFIG and then SETUP).
-Use or range keys to scroll through the menu items.
-Press Enter to select or Exit to quit without changing power-on setup.
If DDC language is selected, user setups cannot be saved as power-on setup.

Model 6485 Picoammeter Instruction Manual Getting Started 1-15
Default settings
The Model 6485 can be restored to one of five setup configurations; factory default
(FACT), three user-saved (USR0, USR1 and USR2), and bus default (GPIB). As shipped
from the factory, Model 6485 powers up to the factory default settings. Factory default set-
tings provide a general purpose setup for front panel operation, while the bus default
(GPIB) settings do the same for remote operation. Factory and GPIB default settings are
listed in Table 1-2.
The instrument will power up to whichever default setup was saved as the power-on setup.
NOTE At the factory, the factory default setup is saved into the USR0, USR1, and USR2
setups.
Front panel setup operation
To save a user setup
1. Configure Model 6485 for the desired measurement application.
2. Press SAVE to access the save setup menu.
3. Use the or  key to display the desired memory location
(0 = USR0, 1 = USR1, 2 = USR2).
4. Press ENTER.
NOTE Saved setups should not be used in DDC mode and will not be recalled upon
power up (in DDC mode).
To restore any setup
1. Press SETUP to display the restore menu:
2. Use the or  key to display the desired setup (FACT, USR0, USR1, USR2, or
GPIB).
3. Press ENTER.
To select power-on setup
1. Press CONFIG and then SETUP to display the power-on menu.
2. Use the or  key to display the desired setup (FACT, USR0, USR1, USR2, or
GPIB).
3. Press ENTER.

1-16 Getting Started Model 6485 Picoammeter Instruction Manual
Remote setup operation
Saving and restoring user setups
The *SAV and *RCL commands are used to save and recall user setups. These commands
are documented in Section 9.
Restoring factory or GPIB default setups
The SYSTem:PRESet command returns Model 6485 to the factory defaults and the *RST
command returns it to the GPIB defaults. The *RST command is documented in Section
11 and SYSTem:PRESet is covered in Section 12.
Selecting power-on setup
The SYSTem:POSetup command is used to select which setup to return to on power-up.
The SYSTem:POSetup command is documented in Section 12.
Table 1-3
Default settings
Setting Factory
(:SYStem:PRESet)
GPIB
(*RST)
Trig Layer (CONF-TRIG):
TRIG:
Arm-In Source Event
TRIG-IN
IMM
*
*
Arm Layer (CONF-ARM):
Arm-In Source Event
Arm Count
Input Trigger Link Line
Source Bypass
Output Trigger Link Line
Output Trigger
IMM
INF
1
NEVER
2
Off
*
1
*
*
*
*
Buffer (STORE):
Count
Disabled
No effect
*
*
Digital Filter (AVG):
Count
Type
Advanced:
Noise Tolerance
Off
10
Moving
No (disabled)
0.0%
*
*
*
*
*
Display Resolution (DIGITS) 5½-digits *
Format byte order Swapped Normal
*This factory (:SYStem:PRESet) and bus (*RST) GPIB defaults are the same. Bus settings that are different
from factory reset are as shown.

Model 6485 Picoammeter Instruction Manual Getting Started 1-17
GPIB:
Address
Language
No effect (On at factory)
No effect (14 at factory)
No effect (SCPI at factory)
*
*
*
Limit Tests:
Limit 1 and Limit 2:
HI and LO Values
Disabled
1, -1
*
*
*
Median Filter:
Rank
Off
1
*
*
MX+B:
“M” Value
“B” Value
Units
Disabled
1.0
0.0
X
*
*
*
*
Log OFF *
M/X+B (reciprocal)
“M” Value
“B” Value
Units
Disabled
1.0
0.0
X
*
*
*
*
Range AUTO *
Rate:
NPLC
Slow
6.0 (60Hz) or 5.0 (50Hz)
*
*
Rel:
Rel Value (VAL)
Off
0.0
*
*
RS-232:
All Settings
No effect (Off at factory)
No effect
*
*
Trigger Layer (CONF-TRIG):
Trig-In Source Event
Trigger Count
Trigger Delay
Input Trigger Link Line
Source Bypass
Output Trigger Link Line
IMM
1
0
1
NEVER
2
*
*
*
*
*
*
Units No effect *
Zero Check Enabled *
Zero Correct Disabled *
Table 1-3 (continued)
Default settings
Setting Factory
(:SYStem:PRESet)
GPIB
(*RST)
*This factory (:SYStem:PRESet) and bus (*RST) GPIB defaults are the same. Bus settings that are different
from factory reset are as shown.

1-18 Getting Started Model 6485 Picoammeter Instruction Manual
Menu
Many aspects of operation are configured through the menus summarized in Table 1-4.
Refer to the Section listed in the table in-depth information. To access the menu, press the
MENU key. Use the and  range keys to scroll through the menu items, and the and
cursor keys to change options. Press ENTER to save any changes made and leave the
menu. Press EXIT to leave the menu without saving changes.
NOTE The MENU key is used to access the menu structure. However, if in remote for
IEEE-488 bus operation (REM annunciator is lit), pressing the menu key has no
effect. Press the LOCAL key to place the unit in local operation, then press the
MENU key to access the menu items.
SCPI programming
SCPI programming information is integrated with front panel operation throughout this
manual. SCPI commands are listed in tables, and additional information that pertains
exclusively to remote operation is provided after each table. The SCPI tables may refer-
ence you to other sections of this manual.
NOTE Except for Section 14, most SCPI tables in this manual are abridged. That is,
they do NOT include most optional command words and query commands.
Optional command words and query commands are summarized as follows.
Table 1-4
MENU structure
Menu item Description Reference
CAL Provides path to the following calibration submenu items:
VOFFSET, COUNT, RUN, DATES, UNLOCK, LOCK, and
SAVE. See reference section for verification and calibration
information.
Section 15,
Section 16
TSTAMP Timestamp format can be ABSolute or DELTa. Section 6
UNITS Readings can be displayed in ENGineering units or
SCIentific notation.
Section 6
TEST Run display or key tests. Section 17
SNUM Displays the units serial number. Section 11
LFREQ Line frequency can be manually set to 50 or 60 Hz, or
AUTOmatically set. The number after AUTO indicates
present detected frequency value.
“Line frequency,”
page 1-13