Keithley 2750 User guide
Model 2750
Multimeter/Switch System
User’s Manual
2750-900-01 Rev. F / August 2011
moc.yelhtiek.www
ECNEDIFNOC FO ERUSAEM RETAERG A
Model 2750 Multimeter/Switch System
User’s Manual
2011, Keithley Instruments, Inc.
All rights reserved.
Cleveland, Ohio, U.S.A.
Document Number: 2750-900-01 Rev. F
Safety Precautions
04/09
The following safety precautions should be observed before using this product and any associated instrumentation.
Although some instruments and accessories would normally be used with non-hazardous voltages, there are
situations where hazardous conditions may be present.
This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety
precautions required to avoid possible injury. Read and follow all installation, operation, and maintenance
information carefully before using the product. Refer to the user documentation for complete product specifications.
If the product is used in a manner not specified, the protection provided by the product warranty may be impaired.
The types of product users are:
Responsible body is the individual or group responsible for the use and maintenance of equipment, for ensuring
that the equipment is operated within its specifications and operating limits, and for ensuring that operators are
adequately trained.
Operators use the product for its intended function. They must be trained in electrical safety procedures and proper
use of the instrument. They must be protected from electric shock and contact with hazardous live circuits.
Maintenance personnel perform routine procedures on the product to keep it operating properly, for example,
setting the line voltage or replacing consumable materials. Maintenance procedures are described in the user
documentation. The procedures explicitly state if the operator may perform them. Otherwise, they should be
performed only by service personnel.
Service personnel are trained to work on live circuits, perform safe installations, and repair products. Only properly
trained service personnel may perform installation and service procedures.
Keithley Instruments products are designed for use with electrical signals that are rated Measurement Category I
and Measurement Category II, as described in the International Electrotechnical Commission (IEC) Standard IEC
60664. Most measurement, control, and data I/O signals are Measurement Category I and must not be directly
connected to mains voltage or to voltage sources with high transient over-voltages. Measurement Category II
connections require protection for high transient over-voltages often associated with local AC mains connections.
Assume all measurement, control, and data I/O connections are for connection to Category I sources unless
otherwise marked or described in the user documentation.
Exercise extreme caution when a shock hazard is present. Lethal voltage may be present on cable connector jacks
or test fixtures. The American National Standards Institute (ANSI) states that a shock hazard exists when voltage
levels greater than 30V RMS, 42.4V peak, or 60VDC are present. A good safety practice is to expect that hazardous
voltage is present in any unknown circuit before measuring.
Operators of this product must be protected from electric shock at all times. The responsible body must ensure that
operators are prevented access and/or insulated from every connection point. In some cases, connections must be
exposed to potential human contact. Product operators in these circumstances must be trained to protect
themselves from the risk of electric shock. If the circuit is capable of operating at or above 1000V , no conductive part
!
of the circuit may be exposed.
Do not connect switching cards directly to unlimited power circuits. They are intended to be used with impedance-
limited sources. NEVER connect switching cards directly to AC mains. When connecting sources to switching cards,
install protective devices to limit fault current and voltage to the card.
Before operating an instrument, ensure that the line cord is connected to a properly-grounded power receptacle.
Inspect the connecting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use.
When installing equipment where access to the main power cord is restricted, such as rack mounting, a separate
main input power disconnect device must be provided in close proximity to the equipment and within easy reach of
the operator.
For maximum safety, do not touch the product, test cables, or any other instruments while power is applied to the
circuit under test. ALWAYS remove power from the entire test system and discharge any capacitors before:
connecting or disconnecting cables or jumpers, installing or removing switching cards, or making internal changes,
such as installing or removing jumpers.
Do not touch any object that could provide a current path to the common side of the circuit under test or power line
(earth) ground. Always make measurements with dry hands while standing on a dry, insulated surface capable of
withstanding the voltage being measured.
The instrument and accessories must be used in accordance with its specifications and operating instructions, or
the safety of the equipment may be impaired.
Do not exceed the maximum signal levels of the instruments and accessories, as defined in the specifications and
operating information, and as shown on the instrument or test fixture panels, or switching card.
When fuses are used in a product, replace with the same type and rating for continued protection against fire hazard.
Chassis connections must only be used as shield connections for measuring circuits, NOT as safety earth ground
connections.
If you are using a test fixture, keep the lid closed while power is applied to the device under test. Safe operation
requires the use of a lid interlock.
If a screw is present, connect it to safety earth ground using the wire recommended in the user documentation.
The symbol on an instrument means caution, risk of danger. The user should refer to the operating instructions
located in the user documenta ti on in all case s wh ere th e symb ol is ma rked on the instrument.
The symbol on an instrument means caution, risk of danger. Use standard safety precautions to avoid personal
contact with these voltages.
The symbol on an instrument shows that the surface may be hot. Avoid personal contact to prevent burns.
The symbol indicates a connection terminal to the equipment frame.
If this symbol is on a product, it indicates that mercury is present in the display lamp. Please note that the lamp
must be properly disposed of according to federal, state, and local laws.
The WARNING heading in the user documentation explains dangers that might result in personal injury or death.
Always read the associated information very carefully before performing the indicated procedure.
The CAUTION heading in the user documentation explains hazards that could damage the instrument. Such
damage may invalidate the warranty.
Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and all test cables.
To maintain protection from electric shock a nd fire, replacement components in mains circuits - including the power
transformer, test leads, and input jacks - must be purchased from Keithley Instruments. Standard fuses with
applicable national safety approvals may be used if the rating and type are the same. Other components that are
not safety-related may be purchased from other suppliers as long as they are equivalent to the original component
(note that selected parts should be purchased only through Keithley Instruments to maintain accuracy and
functionality of the product). If you are unsure about the applicability of a replacement component, call a Keithley
Instruments office for information.
T o clean an instrument, use a damp cloth or mild, water-based cleaner . Clean the exterior of the instrument only . Do
not apply cleaner directly to the instrument or allow liquids to enter or spill on the instrument. Products that consist
of a circuit board with no case or chassis (e.g., a data acquisition board for installation into a computer) should never
require cleaning if handled according to instructions. If the board becomes contaminated and operation is affected,
the board should be returned to the factory for proper cleaning/servicing.
Table of Contents
1 Getting Started
General information ................................................................................. 1-2
Contact information .......................................................................... 1-2
Safety symbols and terms .................................................. ............... 1-2
Inspection .......................................................................................... 1-3
Options and accessories .................................................................... 1-3
Model 2750 features ................................... .................................. ............ 1-5
Plug-in switching modules ....................................................................... 1-6
Pseudocards ...................................................................................... 1-8
Identifying installed switching modules ........................................... 1-8
Front and rear panel familiarization ......................................................... 1-9
Front panel summary ........................................................................ 1-9
Rear panel summary ....................................................................... 1-12
Rack mounting ....................................................................................... 1-13
Power-up ................................................................................................ 1-14
Line power connection .................................................................... 1-14
Line frequency ................................................................................ 1-15
Setting line voltage and replacing fuse ........................................... 1-15
Power-up sequence ......................................................................... 1-16
Keyclick .......................................................................................... 1-16
Display ................................................................................................... 1-17
Status and error messages ............................................................... 1-17
Remote programming — display .................................................... 1-17
Defaults and user setups ......................................................................... 1-19
Saving and restoring setups ............................................................ 1-20
Remote programming — default and user setups ........................... 1-24
Remote programming information ......................................................... 1-25
Quick start exercises .............................................................................. 1-25
Basic DMM measurements — front panel inputs .......................... 1-26
Closing and opening channels — system channel operation .......... 1-28
Simple scanning .............................................................................. 1-31
Trigger and return readings — remote programming ..................... 1-34
2 Closing and Opening Switching Module Channels
Close/open overview ................................................................................ 2-2
Switching module installation and connections ....................................... 2-3
Module installation ........................................................................... 2-3
Connections ...................................................................................... 2-5
Pseudocards ...................................................................................... 2-6
Channel assignments ................................................................................ 2-6
System channel operation ........................................................................ 2-7
2-wire functions ........................................ ......................................... 2-8
4-wire functions (paired channels) ................................................... . 2-8
Controlling the system channel ......................................................... 2-9
Non-amp and non-measure switching modules .............................. 2-13
Multiple channel operation .................................... ................................. 2-15
Controlling multiple channels ......................................................... 2-17
Multiple channel operation anomalies ............................................ 2-21
Dual independent multiplexers ........................................................ 2-23
Identifying installed modules and viewing closed c hannels .................. 2-28
CARD menu ............................................. .................................. ..... 2-28
Switching module queries (remote operation) ................................ 2-30
Relay closure count ................................................................................ 2-32
Reading relay closure count ............................................................ 2-33
Setting count update interval ........................................................... 2-33
Model 7700 switching module .......................................................... ... .. 2-34
Switching module capabilities ........................................................ 2-34
Schematic diagram ................................ .......................................... 2-35
3 Basic DMM Operation
DMM measurement capabilities ............................................................... 3-2
High energy circuit safety precautions ..................................................... 3-3
Performance considerations ...................................................................... 3-4
Warm-up ............................................................................................ 3-4
Autozero ............................................................................................ 3-4
LSYNC (line cycle synchronization) ................................................ 3-5
Remote programming — autozero and LSYNC ............................... 3-6
Channel list parameter (<clist>) ............................................................... 3-7
Voltage measurements (DCV and ACV) .................................................. 3-8
DCV input divider ............................................................................ . 3-8
Connections ....................................................................................... 3-8
Volts measurement procedure ......................................................... 3-11
Crest factor .............................. .................................. ...................... 3-12
Low level considerations ................................................................. 3-12
Current measurements (DCI and ACI) ................................................... 3-14
Connections ..................................................................................... 3-14
Amps measurement procedure ........................................................ 3-15
AMPS fuse replacement (front panel AMPS input) ........................ 3-16
Resistance measurements (Ω2 and Ω4) .................................................. 3-16
Connections ..................................................................................... 3-17
Standard resistance measurements .................................................. 3-19
Offset-compensated ohms ............................................................... 3-20
Dry circuit ohms (DRYCKT) .......................................................... 3-22
Temperature measurements .................................................................... 3-25
Thermocouples ................................................................................ 3-25
Thermistors ..................................................................................... 3-27
4-wire RTDs .............................................................. ...................... 3-28
Connections .................................................................................... 3-28
Temperature measurement configuration ........................................ 3-34
Temperature measurement procedure ............................................. 3-37
Frequency and period measurements ..................................................... 3-38
Trigger level ................................................... ................................. 3-38
Gate time ......................................................................................... 3-38
Connections .................................................................................... 3-39
Frequency and period measurement procedure .............................. 3-40
Continuity testing ........................................................................... ........ 3-41
Connections .................................................................................... 3-41
Continuity testing procedure ........................................................... 3-42
Remote programming for basic measurements ...................................... 3-43
Basic measurement commands ....................................................... 3-43
Basic measurement programming examples .................................. 3-49
Measurement queries ............................................................................. 3-50
:FETCh? .......................................................................................... 3-50
:READ? ........................................................................................... 3-51
:MEASure[:<function>]? ................................................................ 3-51
[:SENSe[1]]:DATA:FRESh? ........................................................... 3-52
[:SENSe[1]]:DATA[:LATest]? ........................................................ 3-52
Examples ......................................................................................... 3-53
4 Range, Digits, Rate, Bandwidth, and Filter
Range ....................................................................................................... 4-2
Measurement ranges and maximum readings ................................... 4-2
Manual ranging ................................................................................. 4-2
Auto ranging ..................................................................................... 4-3
Scanning ............................................................................................ 4-3
Remote programming — range ........................................................ 4-4
Digits ........................................................................................................ 4-5
Scanning ............................................................................................ 4-5
Remote programming — digits ........................................................ 4-6
Rate and bandwidth .................................................................................. 4-8
Rate ................................................................................................... 4-8
Bandwidth ....................................................................................... 4-10
Scanning .......................................................................................... 4-10
Remote programming — rate and bandwidth ................................. 4-11
Filter ....................................................................................................... 4-14
Filter characteristics ........................................................................ 4-14
Remote programming — filter ........................................................ 4-19
5 Relative, Math, Ratio, ChannelAver age, and dB
Relative ..................................................................................................... 5-2
Basic operation .................................................................................. 5-2
Remote programming — rel ............................................................. 5-4
Math .......................................................................................................... 5-8
mX+b ................................................................................................. 5-9
Percent ............................................................................................. 5-10
Reciprocal (1/X) .............................................................................. 5-11
Basic operation ................................................................................ 5-12
Remote programming — math ........................................................ 5-13
Ratio and channel average ..................................... ................................. 5-16
Basic operation ................................................................................ 5-17
Remote programming — ratio and channel average ....................... 5-19
dB ........................................................................................................... 5-21
Remote programming — dB ........................................................... 5-21
6Buffer
Buffer overview ........................................................................................ 6-2
Front panel buffer ..................................................................................... 6-2
Auto clear .......................................................................................... 6-2
Timestamps ....................................................................................... 6-3
Storing readings ................................................................................. 6-5
Recalling readings ............................................................................. 6-6
Buffer statistics .................................................................................. 6-7
Remote programming — buffer ......................... .................................. .... 6-8
Buffer commands .............................................................................. 6-8
Programming example .................................................................... 6-15
7 Scanning
Scanning fundamentals ............................................................................. 7-2
Channel assignments ......................................................................... 7-3
Sequential and non-sequential scans ................................................. 7-3
Scan process .............................................................. ... ..................... 7-3
Trigger models .................................................................................. 7-4
Scan configuration .................................................................................. 7-11
Scan reset ......................................................................................... 7-13
Simple scan ..................................................................................... 7-13
Advanced scan ................................................................................. 7-14
Setting delay .................................................................................... 7-17
Monitor channel .............................................................................. 7-18
Auto channel configuration ............................................................. 7-19
Saving setup .................................................................................... 7-20
Auto scan ......................................................................................... 7-20
Scan operation ............................................ ............................................ 7-21
Basic scan ........................................................................................ 7-21
Manual/external trigger scan ........................................................... 7-22
Monitor scan (analog trigger) ......................................................... 7-23
Remote programming — scanning ........................................................ 7-25
Trigger model .......................................................... ........................ 7-25
Channel setup .................................................................................. 7-26
Buffer .............................................................................................. 7-26
Scanning commands ....................................................................... 7-26
Scanning programming example .................................................... 7-31
Scanning examples ................................................................................. 7-32
External trigger scan ....................................................................... 7-32
Monitor scan ................................................................................... 7-35
8 T riggering
Trigger model ................................................................................. .......... 8-2
Idle .................................................................................................... 8-2
Control source and event detection ................................................... 8-3
Delay (auto or manual) ..................................................................... 8-3
Device action .................................................................................... 8-5
Output trigger .......................................................... .......................... 8-5
External triggering ................................................................................... 8-6
Digital I/O ......................................................... ................................ 8-6
External trigger ................................................................................. 8-7
Voltmeter complete ........................................................................... 8-7
External triggering example .............................................................. 8-8
External triggering with BNC connections ..................................... 8-11
Remote programming — triggering ....................................................... 8-12
Trigger model (remote operation) .............................................. ..... 8-12
Trigger model operation ......................................................... ........ 8-15
Triggering commands ............................................................. ........ 8-16
Programming example .................................................................... 8-17
9 Limits and Digital I/O
Limits ....................................................................................................... 9-2
Scanning ............................................................................................ 9-4
Basic limits operation ....................................................................... 9-4
Digital I/O ................................................................................................ 9-5
Digital input (trigger link input) ....................................................... 9-5
Digital outputs .......................................... ......................................... 9-6
Setting digital output ....................................................................... 9-11
Scanning .......................................................................................... 9-12
Remote programing — limits and digital output ................................... 9-13
Limits and digital output commands .............................................. 9-13
Limits and digital outputs programming example .......................... 9-15
Application — sorting resistors ............................................................. 9-16
Limits .............................................................................................. 9-16
Digital outputs ................................................................................. 9-18
10 Remote Operations
Operation enhancements ........................................................................ 10-2
Pseudocards ..................................................................................... 10-2
Autozero .......................................................................................... 10-2
dB calculation .................................................................................. 10-2
Separate function setups .................................................................. 10-3
DCV input divider ........................................................................... 10-3
Multiple channel operation .............................................. ................ 10-3
GPIB setup .............................................................................................. 10-4
GPIB standards ................................................................................ 10-4
Selecting GPIB and setting primary address ................................... 10-4
GPIB connections ............................................................................ 10-5
General bus commands ........................................................................... 10-7
REN (remote enable) ....................................................................... 10-8
IFC (interface clear) ........................................................................ 10-8
LLO (local lockout) ................................................ ......................... 10-8
GTL (go to local) ............................................................................. 10-8
DCL (device clear) .......................................................................... 10-9
SDC (selective device clear) ........................................................... 10-9
GET (group execute trigger) ........................................................... 10-9
SPE, SPD (serial polling) ................................................................ 10-9
Front panel GPIB operation .................................................................. 10-10
Error and status messages ............................................................. 10-10
GPIB status indicators ................................................................... 10-10
LOCAL key ................................................................................... 10-11
Programming syntax ............................................................................. 10-11
Command words ........................................................................... 10-11
Query commands ........................................................................... 10-13
Case sensitivity .................................................. ............................ 10-13
Long-form and short-form versions .............................................. 10-14
Short-form rules ............................................................................ 10-14
Program messages ..................................................... .................... 10-15
Response messages ....................................................................... 10-17
Message exchange protocol ...................................... .................... 10-17
RS-232 interface operation ................................................................... 10-18
Sending and receiving data ............................................................ 10-18
Baud rate .................................... ................................................... 10-18
Signal handshaking (flow control) .................................. .............. 10-19
Terminator ..................................................................................... 10-19
Selecting and configuring RS-232 interface ................................. 10-20
RS-232 connections ....................................................................... 10-20
Error messages .............................................................................. 10-21
11 Status Structure
Overview ................................................................................................ 11-2
Status byte and SRQ ....................................................................... 11-2
Status register sets ........................................................................... 11-2
Queues ............................................................................................ 11-2
Clearing registers and queues ................................................................. 11-4
Programming and reading registers ....................................................... 11-5
Programming enable registers ......................................................... 11-5
Reading registers ............................................................................. 11-6
Status byte and service request (SRQ) ................................................... 11-6
Status byte register .......................................................................... 11-7
Service request enable register ........................................................ 11-8
Serial polling and SRQ ................................................................... 11-8
Status byte and service request commands ..................................... 11-9
Serial poll programming example ................................................... 11-9
Status register sets ................................................................................ 11-11
Register bit descriptions ................................................................ 11-11
Condition registers ........................................................................ 11-18
Event registers ............................................................................... 11-18
Event enable registers ................................................................... 11-19
Queues .................................................................................................. 11-20
Output queue .................................... .................................. ........... 11-20
Error queue ................................................................................... 11-20
12 Common Commands 13 SCPI Signal Oriented Measurement Commands
CONFigure:<function> [<rang>], [<res>], [<clist>] ............................ 13-3
FETCh? .................................................................................................. 13-5
READ? ................................................................................................... 13-5
MEASure:<function>? [<rang>], [<res>], [<clist>] ............................. 13-7
14 FORMat and Miscellaneous SYST em Commands
FORMat commands ............................................................................... 14-2
FORMat[:DATA] <type>[,<length>] ............................................. 14-2
FORMat:ELEMents <item list> .................................................... 14-5
FORMat:BORDer <name> ............................................................ 14-6
Miscellaneous SYSTem commands ....................................................... 14-7
SYSTem:PRESet ............................................................................. 14-7
SYSTem:VERSion .......................................................................... 14-7
SYSTem:KEY <NRf> ................................................................... 14-7
SYSTem:BEEPer[:STATe] <b> ..................................................... 14-8
15 SCPI Reference Tables
Reference tables ...................................................................................... 15-2
B Model 7700 Connection Guide
Card configuration — schematic ............................................................. B-2
Connections and wiring ........................................................................... B-4
Screw terminals ................................................................................ B-5
Wiring procedure .............................................................................. B-6
Typical connections .......................................................................... B-7
Connection log ............................................................................... B-10
C Status and Error Messages
D Signal Processing Sequence and Data Flow
Signal processing sequence ............................. ........................................ D-2
Basic signal processing .................................................................... D-2
Signal processing using instrument features .............................. ...... D-3
Signal processing using Ratio or Ch Avg ......................................... D-6
Data flow (remote operation) .................................................................. D-7
SENSe and sample buffer ................................................................. D-8
[SENS[1]]:DATA[LATest]? .............................................................. D-9
[SENS[1]]:DATA:FRESh? ............................................................... D-9
FETCh? ............................................................................................ D-9
READ? ............................................................................................. D-9
MEASure? ........................................................................................ D-9
CALC[1]:DATA[LATest]? ............................................................... D-9
CALC[1]:DATA:FRESh? ................................................................. D-9
CALC3:LIM1:FAIL? ..................................................................... D-11
CALC3:LIM2:FAIL? ..................................................................... D-11
TRACe:DATA? ............................................................................... D-11
CALC2:IMM? ................................................................................ D-12
CALC2:IMM .................................................................................. D-12
CALC2:DATA? .............................................................................. D-12
Continuous measurement mode ..................................................... D-12
Scanning ......................................................................................... D-13
E Measurement Considerations
Measurement considerations ......................................... ........................... E-2
Thermoelectric potentials .................................................................. E-2
Thermoelectric generation ................................................................. E-3
Minimizing thermal EMFs ................................................................ E-4
Source resistance noise ..................................................................... E-5
Magnetic fields .................................................................................. E-6
Radio frequency interference ............................................................ E-6
Ground loops ..................................................................................... E-7
Shielding ........................................................................................... E-9
Meter loading .................................................................................. E-10
F T emper ature Equations
Thermocouple equation ............................................................................ F-2
Thermistor equation ................................................................................. F-6
RTD equation ........................................................................................... F-8
G IEEE-488 Bus Overvie w
Introduction .............................................................................................. G-2
Bus description ......................................................................................... G-2
Bus lines ................................................................................................... G-4
Data lines .......................................................................................... G-4
Bus management lines ...................................................................... G-5
Handshake lines ................................................................................ G-5
Bus commands ......................................................................................... G-6
Uniline commands ................................... .................................. ....... G-8
Universal multiline commands ......................................................... G-8
Addressed multiline commands ........................................................ G-9
Address commands ........................................................................... G-9
Unaddress commands ....................................................................... G-9
Common commands ....................................................................... G-10
SCPI commands ........................................................ ...................... G-10
Command codes .............................................................................. G-10
Typical command sequences ........................................................... G-12
IEEE command groups .................................. ................................. G-13
Interface function codes ......................................................................... G-14
1
Getting Started
Quick Start — Of the following section topics, three can be used immediately to quickly
acquaint yourself with fundamental instrument operations. Use QS1 to familiarize yourself with front panel controls, use QS2 to power-up the instrument, and, finally, use QS3 to
perform exercises to operate the instrument.
• General information — Covers general information that includes contact infor-
mation, safety symbols and terms, inspection, and available options and accessories.
• Model 2750 features — Summarizes the features of Model 2750.
• Plug-in switching modules — Summarizes the capabilities of the Keithley
Model 77XX series switching modules.
QS1 • Front and rear panel familiarization — Summarizes the controls and connectors
of the instrument.
• Rack mounting — Covers the options av ailable for rack mounting the Model 2750
in a standard 19-inch rack.
QS2 • Power-up — Co vers line po wer connection, line v oltage setting, fuse replacement,
power line frequency, and the power-up sequence.
• Display — Provides information about the display of the Model 2750.
• Defaults and user setups — Lists the *RST and factory default settings, and cov-
ers the three setup configurations available to the user.
• Remote programming information — Explains how SCPI commands are pre-
sented in this manual.
QS3 • Quick start exercises — Provides abbreviated operating information and exercises
(front panel and remote programming) to acquaint a user with operation basics.
1-2 Getting Started Model 2750 Multimeter/Switch System User’s Manual
!
General information
Contact information
W orldwide phone numbers are listed at the front of this manual. If you have any questions,
please contact your local Keithley representative or call a Keithle y Application Engineer 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 performing the indicated procedure.
The CAUTION heading used in this manual explains hazards that could damage the
instrument. Such damage may invalidate the warranty.
Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-3
Inspection
Model 2750 was carefully inspected electrically and mechanically before shipment. After
unpacking all items from the shipping carton, check for any obvious signs of physical
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 immediately. Save the original packing carton for possible future shipment. The following items
are included with every Model 2750 order:
• Model 2750 with line cord.
• Safety test leads (Model 1751).
• Accessories as ordered.
• Hardware for rack mounting.
• Certificate of calibration.
• Model 2750 User’s Manual (P/N 2750-900-00).
• Manual Addenda (pertains to any improvements or changes concerning the instrument or manual).
If an additional manual is required, order the appropriate manual package. The manual
packages include a manual and any pertinent addenda.
Options and accessories
Plug-in switching modules
NOTE Table 1-1 provides a side-by-side comparison of the following Keithley switch-
ing modules. All multiplexer modules can be configured as two independent
multiplexers.
NOTE The Model 77XX Series Switching Modules Instruction Manual pro vides oper at-
ing and service information for the switching modules. This manual is supplied
with each switching module.
Model 7700 — This differential multiplexer provides 20 channels of 2-pole input, or 10
channels of 4-pole input. The internal cold junction allows direct-connection of thermocouples. It also has two 2-pole channels used exclusively for current input.
Model 7701 — This differential multiplexer provides 32 channels of 2-pole input, or 16
channels of 4-pole input.
Model 7702 — This differential multiplexer provides 40 channels of 2-pole input, or 20
channels of 4-pole input. It also has two 2-pole channels used exclusively for current
input.
1-4 Getting Started Model 2750 Multimeter/Switch System User’s Manual
Model 7703 — This differential multiplexer provides 32 channels of 2-pole input, or 16
channels of 4-pole input.
Model 7705 — This control module provides 40 independent 1-pole switching (SPST)
channels that are isolated from the internal DMM.
Model 7706 — This all-in-one module provides 20/10 channels of 2/4-pole input, 16 digital outputs, two analog outputs, one 32-bit counter with gating and totalizer.
Model 7707 — This module provides 10 channels of 2-pole input, or 5 channels of 4-pole
input. Also provides 32 digital inputs/outputs.
Model 7708 — This differential multiplexer provides 40 channels of 2-pole input, or 20
channels of 4-pole input. The internal cold junction allows direct-connection of thermocouples for temperature measurements.
Model 7709 — This module is configured as a 6 × 8 matrix (six rows, eight columns).
The matrix consists of 48 crosspoint channels and two backplane isolation channels. For
system channel operation, row 1 is connected to DMM Input. For 4-wire measurements,
row 2 is connected to DMM Sense.
Connector and adapter kits for switching modules
Model 7788 DB-50 connector kit — Contains two male DB-50 solder cup connectors
with strain relief connector shells. These connectors mate to the female connectors of the
Models 7703 and 7705 switching modules.
Model 7789 50/25-pin solder cup connector kit — Contains one male DB-50 and one
male DB-25 solder cup connectors. These connectors mate to the female connectors on the
Models 7701 and 7709 switching modules.
Model 7790 ribbon cable adapter kit — Contains one female DB-50, one male DB-50
and one male DB-25 IDC ribbon cable connectors. These connectors are used with the
Models 7701, 7707 and 7709 switching modules.
Cables and adapters (GPIB and trigger link)
Models 7007-1 and 7007-2 shielded GPIB cables — Connect Model 2750 to the GPIB
bus using shielded cables and connectors to reduce electromagnetic interference (EMI).
Model 7007-1 is one meter long; Model 7007-2 is two meters long .
Models 8501-1 and 8501-2 trigger link cables — Connect Model 2750 to other instruments with Trigger Link connectors (e.g., Model 7002 Switch System). Model 8501-1 is
one meter long; Model 8501-2 is two meters long.
Model 8502 trigger link adapter — Lets you connect any of the six trigger link lines of
Model 2750 to instruments that use the standard BNC trigger connectors.
Model 8503 DIN to BNC trigger cable — Lets you connect trigger link lines one (Voltmeter Complete) and two (External Trigger) of Model 2750 to instruments that use BNC
trigger connectors. Model 8503 is one meter long.
Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-5
Rack mount kit
Model 4288-7 rack mount kit — Mounts a Model 2750 in a standard 19-inch rack.
Includes rear brackets to provide additional support for a mainframe that has two or more
switching modules installed.
NOTE The Model 2750 includes hardwar e that allows it to be mounted to the front rails
of a standard 19-inch rack. With two or more switching modules installed, rear
support brackets may be required. The Model 4288-7 rack mount kit includes
rear support brackets.
Model 2750 features
Model 2750 is a 6H-digit high-performance multimeter/data acquisition system. It can mea-
sure voltage (DC and AC), current (DC and AC), resistance (2- and 4-wire), temperature
(thermocouple, thermistor, and 4-wire RTD), frequency and period, and test
continuity.
The Model 2750 has five slots that will accommodate Keithley Model 7700 series switching modules (
measured by the Model 2750. For scanning, each channel can have its own unique setup
(i.e., function, range, digits, etc.).
Table 1-1). Each channel of a switching modul e that is closed or scanned is
More information on the measurement capabilities of the Model 2750 is provided in
“DMM measurement capabilities,” page 3-2. A connection guide for the Model 7700 is
provided in Appendix B.
Additional features of Model 2750 include:
• Setup storage — Five instrument setups (three user, *RST defaults and factory
defaults) can be saved and recalled.
• Offset compensated ohms — A two-measurement process for 4-wire ohms to
cancel the effects of thermal EMFs. Available for the 1Ω, 10Ω, 100Ω, 1kΩ, and
10kΩ, ranges.
• Dry circuit ohms — Low voltage mode (20mV open-circuit clamping) for 4-wire
ohms measurements. Available for the 1Ω, 10Ω, 100Ω, and 1kΩ ranges.
• Math — mX+b, percent, and reciprocal (1/X) calculations provide mathematical
manipulation of readings.
• Relative — Null offsets or establish baseline values.
• Ratio and channel average — Ratio and average calculations for two switching
module channels.
• Buffer — Store up to 110,000 readings in the internal buffer.
• Limits — Two sets of high and low reading limits to test devices.
1-6 Getting Started Model 2750 Multimeter/Switch System User’s Manual
• Digital I/O port — Five digital limit test output lines to control external circuitry.
The digital trigger link and hardware interlock input can also be accessed at this
port.
• Monitor — The Model 2750 can monitor a selected channel. A scan can be trig-
gered to start when the Monitor detects a reached reading limit.
• Remote interface — Model 2750 can be controlled using the IEEE-488 interface
(GPIB) or the RS-232 interface.
Plug-in switching modules
Up to five Keithley Model 77XX series switching modules can be installed in the Model
2750. A side-by-side comparison of the switching modules is provided in Table 1-1.
Basic close/open operation for switching module channels is provided in Section 2,
while scanning is covered in Section 7. Connec tion i nforma tion fo r the Mo del 77 00
switching module is provided in Appendix B. For all other switching modules, connection information is provided in the packing list that was shipped with each switching
module.
Table 1-1
Model 77XX series switching modules
2-pole operation
4-pole operation
1-pole operation
Measure volts
Measure amps
Measure ohms
Cold junction
for thermocouples
Relay type
Connector type
Configuration
Unique features
1
2
Model 7700 Model 7701 Model 7702 Model 7703 Model 7705
20 channels
10 channel pairs
N/A
300V Max
Ch 21 and 22,
3A Max
2/4-wire
Yes
Latching electromechanical
Oversized screw
terminals
Multiplexer
All DMM
functions
32 channels
16 channel pairs
N/A
150V Max
No
2/4-wire
No
Latching electromechanical
1 female DB-50
1 female DB-25
Multiplexer
All DMM
functions except
amps
40 channels
20 channel pairs
N/A
300V Max
Ch 41 and 42,
3A Max
2/4-wire
No
Latching electromechanical
Oversized screw
terminals
Multiplexer
All DMM
functions
32 channels
16 channel pairs
N/A
300V Max
No
2/4-wire
No
Non-latching
reed
2 female
DB-50s
Multiplexer
All DMM
functions except
amps
N/A
N/A
40 channels
300V Max
No
No
No
Latching electromechanical
2 female
DB-50s
Independent
SPST channels
Multiple channel operation
only
Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-7
Table 1-1 (continued)
Model 77XX series switching modules
Model 7706 Model 7707 Model 7708 Model 7709
2-pole operation
4-pole operation
1-pole operation
Measure volts
Measure amps
Measure ohms
Cold junction
20 channels
10 channel pairs
N/A
300V Max
No
2/4-wire
Yes
10 channels
5 channel pairs
N/A
300V
No
2/4-wire
No
40 channels
20 channel pairs
N/A
300V Max
No
2/4-wire
Yes
8 channels
4 channel pairs
N/A
300V Max
No
2/4-wire
No
for thermocouples
Relay type
1
Connector type
Configuration
Unique features
Latching electromechanical
Mini screw
terminals
2
Multiplexer
16 digital outputs, 2 analog
outputs, one
counter,
totalizer
Latching electromechanical
1 male DB-50
1 female DB-25
Multiplexer
32 digital
inputs/outputs
Latching electromechanical
Oversized screw
terminals
Multiplexer
All DMM functions except
amps
Latching electromechanical
1 female DB-50
1 female DB-25
Matrix
6 × 8 matrix.
For system
channel operation, rows 1 and
2 connect to
DMM
1. Latching relays hold their open/close state after the Model 2750 is turned off. When turned on, all relays open after a few seconds.
2. All multiplexers can be configured as two independent multiplexers.
1-8 Getting Started Model 2750 Multimeter/Switch System User’s Manual
Pseudocards
Using remote programming, you can assign a pseudocard to an empty switching module
slot. With a pseudocard “installed,” the Model 2750 will operate as if the switching module is installed in the Model 2750. This feature allows you to configure your system without having the actual switching module installed in the unit. There is a pseudocard for
every Keithley Model 77XX series switching module. For details, see “Pseudocards,”
page 2-6.
Identifying installed switching modules
On power-up, the model numbers of installed switching modules are displayed briefly.
While in the normal display state, slot indicators on the right side of the display indicate
which slots have a switching module or pseudocard installed.
NOTE If a Model 7700, 7701, 7702, 7703, 7705, 7708, or 7709 switching module is
removed while the Model 2750 is on, the slot indicator for that slot will remain
on, and the instrument will operate as if the module is installed. That is, the
Model 2750 will operate as if the pseudocard is installed.
If a Model 7706 or 7707 is removed while power is on, error +523 “Card hardware error” will occur, and the module will be removed from the system.
In general, it is not recommended to install or remove switching modules with
the power on.
The CARD menu and remote query commands can be used to identify modules installed
in the mainframe. For details, see “Switching module installation and connections,”
page 2-3.
Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-9
MODEL 2750 MULTIMETER/SWITCH SYSTEM
INTEGRA SERIES
SLOT 1
SLOT 3
SLOT 4
SLOT 5
SLOT 2
3A, 250V
MATH
OUTPUT
RATIO
CH AVG
CONT
PERIOD SENSOR
OCOMP
DCV
DCIACV
ACIΩ2Ω4
FREQ
TEMP
RANGE
AUTO
RANGE
EXIT ENTER
DIGITS RATE
RELFILTER
TRIG
EX TRIG
STORE
RECALL
OPEN
LIMITS ON/OFFDELAY
DRYCKT
SAVE SETUP
CONFIG HALT
TYPE
LSYNC
TEST
MONITOR
STEP SCAN
CH-OFF CARD
CLOSE
RS-232
GPIB
POWER
SHIFT
LOCAL
7
1
4
3
6
2
!
F
500V
PEAK
FRONT/REAR
HI
INPUT
LO
SENSE
Ω 4 WIRE
INPUT
350V
PEAK
1000V
PEAK
R
CAT I
AMPS
5
Fr ont and rear panel familiarization
Front panel summar y
The front panel of Model 2750 is shown in Figure 1-1.
Figure 1-1
Model 2750 front panel
NOTE Most keys provide a dual function or operation. The nomenclature on a key indi-
cates its unshifted function/operation, which is selected by pressing the key.
Nomenclature (in blue) above a key indicates its shifted function. A shifted function is selected by pressing the SHIFT key and then the function/operation key.
1 Special keys and power switch:
SHIFT Use to select a shifted function or operation.
LOCAL Cancels GPIB remote mode.
POWER Power switch. In position turns 2750 on (I), out position turns it off (O).
2 Function and operation keys:
Top Row
Unshifted
DCV Selects DC voltage measurement function.
ACV Selects AC voltage measurement function.
DCI Selects DC current measurement function.
ACI Selects AC current measurement function.
Ω2 Selects 2-wire resistance measurement function.
Ω4 Selects 4-wire resistance measurement function.
FREQ Selects frequency measurement function.
TEMP Selects temperature measurement function.
Shifted
MATH Configures and controls mX+b, percent, or reciprocal (1/X) calculation.
OUTPUT Configures and controls digital and audio (beeper) output for limits.
RATIO Enables/disables channel ratio.
CH-AVG Enables/disables channel average.
CONT Configures and controls continuity test.
OCOMP Enables/disables offset compensated ohms with Ω4 function selected.
PERIOD Selects period measurement function.
SENSOR Configures temperature measurements.
1-10 Getting Started Model 2750 Multimeter/Switch System User’s Manual
Middle Row
Unshifted
EXTRIG Selects external triggering (front panel, bus, trigger link) as the trigger source.
TRIG Triggers a measurement when in external triggering (EX TRIG).
STORE Sets the number of readings to store and enables the buffer.
RECALL Displays stored readings and buffer statistics. Use the
igate through buffer.
FILTER Enables/disables filter for selected function.
REL Enables/disables relative for selected function.
, , Δ , and ∇ keys to nav-
and Dual function — Manually scans switching channels. When in a menu, these keys
control cursor position for making selections or change values.
Shifted
DELAY Sets user delay between trigger and measurement.
DRYCKT Selects dry circuit ohms (Ω4 must first be selected).
LIMITS Sets upper and lower limits for readings.
ON/OFF Enables/disables limits.
TYPE Configures and enables filter for selected function.
MONITOR Selects and enable/disables monitor channel.
CH-OFF Disables channel for a scan (must be in scan channel setup mode).
CARD Identifies switching modules installed in mainframe. Set up switching modules that
Bottom Row
Unshifted
OPEN Opens closed channel.
CLOSE Closes specified channel.
STEP Steps through channels; sends a trigger after each channel.
SCAN Scans through channels; sends a trigger after last channel.
DIGITS Sets display resolution for all functions.
RATE Sets measurement speed (fast, medium, or slow) for all functions.
EXIT Cancels selection, moves back to measurement display.
ENTER Accepts selection, moves to next choice or back to measurement display.
Shifted
SAVE Saves up to three instrument setups for future recall, and selects power-on setup.
SETUP Restores a default setup (factory or *RST) or a saved setup. Enables/disables buffer
CONFIG Selects and configures a simple scan or an advanced scan.
HALT Disables step/scan.
TEST Selects the calibration menu, display test or the key-press test.
LSYNC Enables/disables line cycle synchronization. When enabled, noise induced by the
GPIB Enables/disables GPIB and selects address.
RS-232 Enables/disables RS-232 interface; selects baud rate, flow control, and terminator.
require configuration. View closed channels and channel settings for switching mod-
ules that require configuration.
auto clear, auto scan, and auto channel configuration. Sets timestamp, date, and
time. Displays serial number of Model 2750.
power line is reduced at the expense of speed.
3 Range keys:
Δ and ∇ Dual function — Selects the next higher/lower measurement range for the selected
function. When in a menu, these keys make selections or change values.
AUTO Enables/disables autorange for the selected function.
Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-11
4 Display annunciators:
* (asterisk) Readings being stored in buffer.
↔ (more) Indicates additional selections are available.
))) (speaker) Beeper on for continuity or limits testing.
4W 4-wire resistance or 4-wire RTD temperature reading displayed.
DCKT Dry circuit resistance reading displayed.
~AC AC function selected (ACV, dB, or ACI).
AUTO Auto range enabled.
BUFFER Recalling readings stored in buffer.
CHAN Setup or a reading for a switching channel displayed.
DELTA Channel average enabled.
ERR Questionable reading, or invalid cal step.
FAST Fast reading rate selected.
FILT Filter enabled for selected function.
HIGH Reading has reached or exceeded the enabled high limit.
LSTN Instrument addressed to listen over GPIB.
LOW Reading has reached or exceeded the enabled low limit.
MATH mX+b, percent, or reciprocal (1/X) calculation enabled.
MED Medium reading rate selected.
MON Monitor channel displayed.
OCOMP 4-wire offset compensated ohms enabled.
RATIO Channel ratio enabled.
REAR Front panel input terminals disconnected.
REL Relative enabled for selected function.
REM Instrument in GPIB remote mode.
SCAN Scanning operation being performed.
SHIFT Accessing a shifted key.
SLOW Slow reading rate selected.
SRQ Service request over GPIB.
STAT Displaying buffer statistics.
STEP Stepping operation being performed.
TALK Instrument addressed to talk over GPIB bus.
TIMER Timer controlled triggering in use.
TRIG External triggering selected (trigger link, TRIG key, or GPIB).
Digital input/output or analog output active (set to non-default value).
5 Slot indicators:
Lit lamp indicates that the slot has a switching module or pseudocard installed in it. When the VIEW
option of the CARD menu is used, only the lamp that corresponds to the selected slot is turned on.
6 INPUTS switch:
Use to select front panel inputs (out; F) position, or switching module inputs (in; R) position.
NOTE For remote programming, the following command queries the INPUTS switch
position:
SYSTem:FRSwitch? ' Query INPUTS switch; 0 = rear, 1 = front.
7 Front panel inputs:
INPUT HI and LO Used for DCV, ACV, Ω2, CONT, FREQ, PERIOD, and thermocouple/thermistor
TEMP measurements.
SENSE HI and LO Use with INPUT HI and LO for
AMPS Use with INPUT LO for DCI and ACI measurements.
Amps fuse holder Holds current fuse for front panel amps input.
Ω4 and RTD TEMP measurements.
1-12 Getting Started Model 2750 Multimeter/Switch System User’s Manual
IEEE-488
MADE IN
U.S.A.
!
CAT I
DIGITAL I/O TRIG. LINK
!
SLT
2
SLT
1
SLT
3
SLT
4
SLT
5
RS-232
KEITHLEY
SLOT COVER
KEITHLEY
SLOT COVER
KEITHLEY
SLOT COVER
5
4321
6
Rear panel summary
The rear panel of Model 2750 is shown in Figure 1-2. As shown, slot covers are installed
on unused slots.
WARNING Slot covers must be installed on unused slots to prevent personal con-
tact with high voltage circuits.
Figure 1-2
Model 2750 rear panel
1 DIGITAL I/O
Male DB-9 connector for digital input (trigger link in) and digital outputs.
2 TRIG LINK
Eight-pin micro-DIN connector for sending and receiving trigger pulses among connected instruments.
Use a trigger link cable or adapter, such as Models 8501-1, 8501-2, 8502, and 8503.
3 RS-232
Female DB-9 connector for RS-232 operation. Use a straight-through (not null modem) DB-9 shielded
cable.
4 IEEE-488
Connector for IEEE-488 (GPIB) operation. Use a shielded cable, such as Models 7007-1 and 7007-2.
5 Power module
Contains the AC line receptacle, power line fuse, and line voltage setting. The instrument can be configured for line voltages of 100V/120V/220V/240VAC at line frequencies of 50 or 60Hz.
WARNING Slot covers must be installed on unused slots to prevent personal con-
6 Slots 1 through 5
Five slots to accommodate Keithley Model 77XX series s witching modules. T he Model 2750 is shipped
from the factory with slot covers installed. Please note additional slot covers can be requested from Keithley Instruments.
tact with high voltage circuits.
Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-13
1.75”
Left Front
Rack Rail
Retaining Clips
with Nuts
Rack mounting
The Model 2750 can be mounted in a standard 19-inch rack. For a mainframe that has one
or no switching modules installed, the Model 2750 can be secured to the front rails of the
rack.
The hardware necessary to secure the mainframe to the front rails of the rack is supplied
with the Model 2750. The supplied hardware kit includes four dress screws and four
retaining clips. Each retaining clip has a captive nut.
Perform the following steps to mount the Model 2750 to front rails of the rack:
WARNING Make sure the Model 2750 is turned off, the line cord is disconnected,
and it is not connected to any external circuitry.
1. Select a location in the rack. The mainframe takes up 3H-inches of vertical space.
2. Using Figure 1-3 as a guide, install two retaining clips on the left front rail. Slide
each retaining clip over a mounting hole such that the captive nut is positioned on
the inside of the rack cabinet. In a simila r manner, install two retaining clips on the
right front rail.
3. Remove the four foot assemblies from the bottom of the Model 2750. The retaining
screw for an assembly is located under the rubber foot. Simply pull off the rubber
feet to gain access to the screws. Retain these foot assemblies for future use.
4. Position the Model 2750 in the rack and loosely attach the front panel to the rack
rails using the four supplied dress screws.
5. Tighten the four dress screws.
CAUTION For a Model 2750 that has two or more installed switching modules,
rear brackets are required to support the additional weight. The Model
4288-7 is a rack mount kit for the Model 2750 that uses rear support
brackets.
Figure 1-3
Rack preparation
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