Text preview for : 2750-900-01F.pdf part of
| Home
w w w . k e i th l e y. c o m
Model 2750
Multimeter/Switch System
User's Manual
2750-900-01 Rev. F / August 2011
A G R E A T E R M E A S U R E O F C O N F I D E N C E
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 documentation in all cases where the symbol is marked 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 and 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.
To 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 channels .................. 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 () ............................................................... 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 (2 and 4) .................................................. 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[:]? ................................................................ 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, Channel Average, 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
6 Buffer
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 Triggering
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: [], [], [] ............................ 13-3
FETCh? .................................................................................................. 13-5
READ? ................................................................................................... 13-5
MEASure:? [], [], [] ............................. 13-7
14 FORMat and Miscellaneous SYSTem Commands
FORMat commands ............................................................................... 14-2
FORMat[:DATA] [,] ............................................. 14-2
FORMat:ELEMents - .................................................... 14-5
FORMat:BORDer ............................................................ 14-6
Miscellaneous SYSTem commands ....................................................... 14-7
SYSTem:PRESet ............................................................................. 14-7
SYSTem:VERSion .......................................................................... 14-7
SYSTem:KEY ................................................................... 14-7
SYSTem:BEEPer[:STATe] ..................................................... 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 Temperature Equations
Thermocouple equation ............................................................................ F-2
Thermistor equation ................................................................................. F-6
RTD equation ........................................................................................... F-8
G IEEE-488 Bus Overview
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 your-
self with front panel controls, use QS2 to power-up the instrument, and, finally, use QS3 to
perform exercises to operate the instrument.