Tektronix 7014 Instruction Manual
Instruction Manual
3%Channel Thermocouple/
General Purpose Multiplexer Card
Contains Operating and Servicing information
Model 7014
WARRANTY
Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year
from date of shipment.
Kcithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable
batteries, diskettes, and documentation.
During the warranty period, WC will, at our option, either repair or replace any product that proves to be defect&
To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Cleveland, Ohio.
You will be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service
facility. Repairs will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for
the balance of the original warranty period, or at least 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or
misuse of any product or part, This warranty also does not apply to fuses, software, non-rechargcahle batteries, damage from
battery leakage, or problems arising from normal wear or failure to follow instructions.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY
IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT,
INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS
INSTRUMENTS AND SOFTWARE EVEN IF KFITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE
OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY
PERSON, OR DAMAGE TO PROPERTY.
Model 7014 Instruction Manual
01992, Keithley Instruments, Inc.
All Rights Reserved
Cleveland, Ohio, U. S. A.
Manual Print History
The print history shown below lists the printing dates of all Revisions and Addenda created for this manual. The
Revision Level letter increases alphabetically as the manual undergoes subsequent updates. Addenda, which are
released between Revisions, contain important change information that the user should incorporate immediately
into the manual. Addenda are numbered sequentially. When a new Revision is created, all Addenda associated
with tlw previous Revision of the manual are incorporated into the new Revision of the manual. Each new Revision includes a revised copy of this print history page.
revision A (Document Number 70~901.01) ............................................................................ October 1992
Revision B (Document Number 7014.901-01). ........................................................................
November 1992
Safety Precautions
The following safety precautions should be observed bcforc using
this product and any associated instrumentation. Although some instmmcnt~ and accessories would nomxally bc used with non-hazardous voltages, there are situations where hazardous conditions
may be presem.
This producl is intended for use by qualified personnel who recognize shock hazards and are familiar with the safely precautions rcquired to avoid possible injury. Read the operating information
arcfully before using the product.
The types of product users are:
Responsible body is the individual or group responsible for the USC
and maintenance of cquipmcnt. for ensuring that the equipment is
operated within its spccitications and operating limits, and for en-
suring that operators are adequately trained.
Operators use the product for its intended function. They mull 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 pafonn routine procedures on the product
to keep it operating, for example, setting the line voltage or replacing consumable materials. Maintenance procedures are described in
the manual. The procedures explicitly state if the operator may pcrform them. Otherwise, they should be performed only by service
pxs0”“e1.
Service personnel are trained to work on live circuits, and perform
safe installations and repairs of pmducts. Only properly trained service personnel may perform installation and sen%x procedures.
Users of this product must bc protected from electric shock at all
times. The rcsponsiblc body must ensure that users are prevented
access and/or insulated from every connection point. In some c.xses.
connections must bc exposed to potendal human contact. Product
users in these circumstances must bc trained to protect thcn~scl~es
from the risk of electric shock. If the circuit is capable of operating
at or above 1000 volts, no conductive part of the circuit may be
exposed.
As described in the lntemetional Elcctrmcchnical Commission
(IEC) Standard IEC 664, digital muldmeter measuring circuits
(e.g.. Kcithley Models 175A, 199. 2000. 2001. 2002. and 2010) arc
lnstallatiou Category II. All other instruments signal terminals are
Installation Category I and must not bc connected to mains.
Do not connect switching cards directly to unlimited power circuits.
‘hey arc intended to be used with impcdancc limiled sources.
NEVER connect switching cards directly to AC mains. When con-
necting sources to switching cards. install protective devices to iim
it fault current and voltage to the card
Before operating an inwument, make sure the lint cord is connects
ed to B properly grounded power receptacle. lnspcct the connecting
cables. test leads, and jumpers for possible wear, cracks. or brwks
before each use.
For maximum safety, do not touch the product. test cables, or .vly
other inatrumcnrs while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge
any capacitors before: connecting or dirconnecdng cables or jumpy
em, instdting Or removing switching cards, or making internal
changes, such as installing or removing jumpers.
Exercise extreme caution when a shock hazard is present. Lethal
voltage may be present on cable connector jacks or test fixtures. The
American National Sandards Institute (ANSI) states that B 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.
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 ,,,~a~“rcm~“ts with dry hands while standing on a
dry, insulaled 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 cquipment may be impaired.
The WARNING heading in a manual explains dangers that might
result in personal injury or death. Always read the associated information very canfully before performing the indicated procedure.
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 fame 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.
Ifa@ screw is present, connect it to safety earth ground using the
wire recommended in the user documentation.
Then. symbol on an instrument indicates that the user should reker to the operating instructions located in tbc manual.
men
sure 1000 volts or more, including tbc combined effect of normal
and common mode voltages. Use standard safety precautions to
avoid personal contact with thcsc voltages.
symbol on an instrument shows that it am source ormea-
The CAUTION heading in a manual explains hazards that could
damage the instrument. Such damage may invalidate the warranty.
Instrumentation and accessarics 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 tire, replacement
components in mains circuits, including the power transformer, test
leads, and input jacks, must be purchased from Keirhley hutnmenrs. 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 arc equivalent to the original component. (Note that selected parts should be purchased only through Keithley lnstmments
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, USC a damp cloth or mild, water based
cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instmmcnt or allow liquids to enter or spill
on the instrument. Products that consist of a circuit board with no
case or chassis (c.g., data acquisition board for installation into a
computer) should never require cleaning if handled according to instructions. If the board becomes contaminated and opertiion is affected, the board should bc returned to the factory for proper
clcaning/scrvicing.
Rev. IO/99
39 Channel Thermocouple/General Purpose Multiplexer
10.7’C ((PC to 18°C and 2FC to M”C).
REFERENCE o-: +*wu”Pc ,+SP.mn” at 0°C).
Model 7014
Bankss-‘
+
1 General Information
Table of Contents
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.7.1
1.72
1.7.3
1.7.4
1.8
2.1
2.2
2.2.1
2.2.2
2.2.3
2.2.4
2.3
2.3.1
2.3.2
2.4
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
2.5
2.5.1
2.5.2
Introduction
Features..
Warranty information..
Manual addenda
Safety
Specifications
Unpacking and
Inspection for damage.. ...........................................................................................................................
Shipping contents.. ...................................................................................................................................
Instruction manual.. .................................................................................................................................
Repacking for shipment..
Optional accessories
......................................................................................................................................................
............................................................................................................................................................
....................................................................................................................................
..............................................................................................................................................
symbols and terms ...............................................................................................................................
....................................................................................................................................................
inspection.. ............................................................................................................................
........................................................................................................................
.........................................................................................................................................
Multiplexing Basics
Introduction
Thermocouple measurements
Definitions ..................................................................................................................................................
Theory .........................................................................................................................................................
Measurement procedure
Measuring example.. .................................................................................................................................
Basic multiplexer configurations
Multiplexer bank-to-bank jumpers
Backplane jumpers ...................................................................................................................................
Typical multiplexer switching schemes..
Thermocouple switching..
Single-ended switching ...........................................................................................................................
Differential switching ..............................................................................................................................
Sensing
SMU connections
Multiplexer expansion
Two-card switching systems
Mainframe multiplexer expansion
......................................................................................................................................................
........................................................................................................................
..........................................................................................................................
...................................................................................................................
........................................................................................................
......................................................................................................
........................................................................................................................
.......................................................................................................................................................
......................................................................................................................................
...................................................................................................................................
................................................................................................................
......................................................................................................
1-l
1-l
1-2
1-2
1-2
1-2
t-2
1-2
1-2
l-3
l-3
l-3
2-l
.2-l
2-l
2-l
2-2
2-2
2-3
2-4
2-6
2-7
2-7
2-8
2-8
2-9
2-9
Z-10
Z-10
2-l 1
3
Card Connections & Installation
3.1
3.2
3.3
3.3.1
3.3.2
3.3.3
3.4
3.4.1
3.4.2
3.4.3
3.5
4
4.1
4.2
4.3
4.3.1
4.3.2
4.3.3
4.4
4.4.1
4.4.2
4.4.3
4.4.4
4.5
4.5.1
4.5.2
4.5.3
4.5.4
4.5.5
4.5.6
4.5.7
Introduction..
Handling precautions
Connections .......................................................................................................................................................
Bank-to-bank jumpers..
Backplane jumpers
Screw terminal
Typical connection
Single card system..
Two-card system..
Two-mainframe
Model 7014 installation
.....................................................................................................................................................
......................................................................................................................................
............................................................................................................................
...................................................................................................................................
connector card ...............................................................................................................
schemes.. ..........................................................................................................................
..................................................................................................................................
.....................................................................................................................................
system.. .........................................................................................................................
and removal ..........................................................................................................
3-1
3-l
3-l
3-2
3-4
3-4
3-6
3-6
3-9
3-9
3-12
Operation
Introduction.. .....................................................................................................................................................
Power limits.. .....................................................................................................................................................
Mainframe control
Channel assignments
Front panel control
IEEE-488 bus
Multiplexer switching examples
Thermocouple
Resistor testing..
Transistor testing
Resistor temperature coefficient testing..
Measurement considerations
Thermocouple
Path isolation..
Magnetic fields..
Radio frequency
Ground loops
Keeping connectors
AC frequency
of multiplexer card..
...............................................................................................................................
...................................................................................................................................
operation.. ..........................................................................................................................
....................................................................................................................
scanning ..........................................................................................................................
........................................................................................................................................
....................................................................................................................................
........................................................................................................................
measurement error
.........................................................................................................................................
......................................................................................................................................
interference.. ..............................................................................................................
..........................................................................................................................................
clean.. ....................................................................................................................
response.. ........................................................................................................................
.......................................................................................................
.............................................................................................
sources ........................................................................................
4-l
4-1
4-l
4-l
4-3
4-4
4-5
4-5
4-5
4.10
4.10
4.13
4-13
4-14
4-15
4-15
4-15
4-16
4-16
5 Service Information
5.1
5.2
5.3
5.3.1
5.3.2
5.3.3
5.3.4
5.3.5
5.3.6
5.3.7
5.3.8
5.4
ii
Introduction.. .....................................................................................................................................................
Handling and cleaning
Performance verification ...................................................................................................................................
Environmental
Recommended
Reference junction
Channel resistance
Offset current
contact potential tests.. ............................................................................................................................
Bank and channel-to-channel isolation tests
Differential and common-mode isolation tests
Calibration..
tests.. ..................................................................................................................................
......................................................................................................................................................
5-l
precautions.. .............................................................................................................
conditions .......................................................................................................................
equipment ......................................................................................................................
test ..............................................................................................................................
tests.. .........................................................................................................................
........................................................................................
..................................................................................
5-l
5-2
5-2
5-2
5-3
5-5
5-6
5-E
5.9
5.13
5.15
5.4.1
5.4.2
5.5
5.6
5.6.1
5.6.2
5.6.3
5.6.4
5.6.5
5.7
5.7.1
5.7.2
5.7.3
Calibration with thermistor probe.. .....................................................................................................
Calibration with thermocouple wire..
Special handling of static-sensitive devices
..
Prlnc1ples of operation
Block diagram
ID data cncults .........................................................................................................................................
Relay control
Reference junction .................................................................................................................................
Power-on safeguard
Troubleshooting
Troubleshooting equipment
Troubleshooting access
Troubleshooting procedure
...................................................................................................................................
........................................................................................................................................
..........................................................................................................................................
..............................................................................................................................
............................................................................................................................................
................................................................................................................
.........................................................................................................................
.................................................................................................................
..................................................................................................
................................................................................................
.5-15
5-17
5-19
5-19
5-19
5-20
5-21
5-21
5-21
5-21
5-21
5-21
5-22
6
6.1
6.2
6.3
6.4
6.5
Replaceable Parts
Introduction
Parts lists..
Ordering information
Factory service
Component layouts and schematic diagrams.
.....................................................................................................................................................
.........................................................................................................................................................
.....................................................................................................................................
.................................................................................................................................................
6-l
6-1
6-l
6-l
............................................................................................
6-l
iii/iv
List of I Ilustrations
2
Figure 2-1
Figure 2-2
Figure 2-3
Figure 2-4
Figure 2-5
Figure 2-6
Figure 2-7
Figure 2-8
Figure 2-9
Figure Z-10
Figure 2-11
Figure 2-12
Figure 2-13
Figure 2-14
Figure 2-15
3
Figure 3-l
Figure 3-2
Figure 3-3
Figure 3-4
Figure 3-5
Figure 3-6
Figure 3-7
Figure 3-8
Figure 3-9
Figure 3-10
Figure 3-11
Figure 3-12
Figure 3-13
Multiplexing Basics
Thermocouple measurement
Model 7014 simplified schematic
Four 1 x 10 multiplexer configuration
Two 1 x 20 multiplexer configuration
One 1 x 40 multiplexer configuration (jumpers installed)
Model 7001 analog backplane..
Bank connections to backplane
Thermocouple switching example..
Single-ended switching example
Differential switching example
Sensing example
SMU connections.. ..................................................................................................................................
Two separate multiplexer systems
Multiplexer input expansion example
Mixed card type example
.......................................................................................................................................
...................................................................................................................
...........................................................................................................
(jumpers not installed) .........................................................
(jumpers installed). ................................................................
................................................................. 2-5
..............................................................................................................
.............................................................................................................. 2-7
.......................................................................................................
...........................................................................................................
.............................................................................................................. 2-8
...................................................................................................... 2-l 1
................................................................................................
......................................................................................................................
2-2
2-3
2-4
2-5
2-6
.2-7
.2-8
2-Y
Z-10
Z-12
2-12
Card Connections & Installation
Bank-to-bank jumper locations
Bank-to-bank jumper termmal ldenhficahon
Connector card mounting screw..
Bank-to-bank jumper installation
Backplane jumpers ...................................................................................................................................
Model 7014 screw terminal connector card
Typical screw terminal connections
Cable clamp for screw terminal connector card
Single card (1 x 39) system example..
Single card (1 x 19 and 1 x 20) system example..
Two-card system example
Two-mainframe system example..
Model 7014 card installation in Model 7001
.............................................................................................................. 3-2
..........................................................................................
...........................................................................................................
..........................................................................................................
..........................................................................................
......................................................................................................
..................................................................................
.....................................................................................................
..................................................................................
.................................................................................................................... 3-10
....................................................................................................... 3-11
.......................................................................................
3-3
3-3
3-4
3-4
3-5
3-6
3-6
3-7
3-8
3-13
4
Figure 4-l
Figure 4-2
Operation
Channel status display ,,,,,,,....,.,,,,..,,,,,,,.,,.,,,,,,....,,.,,...,...,,,,,,,,,,.,....,,......,.......................,,,..................... 4-2
Display organization for multiplexer channels . . . . . .
4-2
”
Figure 4-3
Figure 4-4
Figure 4-5
Figure 4-6
Figure 4-7
Figure 4-8
Figure 4-9
Figure 4-10
Figure 4-11
Figure 4-12
Figure 4-13
Figure 4-14
Model 7014 programming channel assignments
Thermocouple scanning ...........................................................................................................................
Z-wire resistance testing ..........................................................................................................................
4.wire resistance testing ..........................................................................................................................
Low resistance testing.. ............................................................................................................................
Configuration for current gain and common-emitter test
Resistor temperature coefficient testing..
Typical common-emitter characteristics
..
Path lsolatlon resistance.. ........................................................................................................................
Voltage attenuation by path isolation
Power lie ground loops
....................................................................................................................... 4-16
............................................................................................. 4-12
.............................................................................................
resistance ............................................................................... 4-15
Eliminating ground loops .....................................................................................................................
................................................................................. 4-3
4-6
47
4-7
4-9
................................................................
4-11
4-13
4-14
4-16
5
Figure 5-l
Figure 5-2
Figure 5-3
Figure 5-4
Figure 5-5
Figure 5-6
Figure 5-7
Figure 5-8
Figure 5-9
Figure S-10
Figure 5-11
Figure 5-12
Figure S-13
Service Information
Reference junction test
Path resistance test connections
Differential offset current test connections..
contact potential test connections
..
Bank lsolahon test connections ...............................................................................................................
Channel-to-channel isolation test connections..
Differential isolation test connections
Common-mode isolation test connections..
Calibration with thermistor probe
Calibration with thermocouple wire
Model 7014 block diagram
Start and stop sequences
Transmit and acknowledge sequence ‘
.............................................................................................................................. 5-4
............................................................................................................. 5-5
.........................................................................................
.........................................................................................................
5-7
5-8
5-9
...........................................................................
..... .
5-11
................................................................................................. S-13
........................................................................................ S-15
........................................................................................................
5-16
.................................................................................................... 5-18
.................................................................................................................... S-19
........................................................................................................................ S-20
.................................................................................................
5-20
vi
List of Tables
3
Table 3-l
4
Table 4-1
5
Table 5-1
Table 5-2
Table 5-3
Table 5-4
Table 5-5
Table 5-6
Card Connections & installation
Bank-to-bank jumpers (refer to Figure 3-2) ,,,......,.,.,,,,,,,,,,,,,,,,..........,............
,,,,,,,,,........................ 3-3
Operation
Paired Channels in 4-p& Operation . . ..___....,,...............................................~.
,......,.,,,,....,.....,.,....... 4-8
Service Information
Verification and calibration equipment
Bank isolation test summary
Channel-to-channel isolation test summary
Differential and common-mode isolation
Recommended troubleshooting equipment
Troubleshooting procedure
............................................................................
..................................................................................
..........................................................
..................................................
testing.. ........................................
...................................................
................................. 5-3
............................... 5-10
............................... 5-12
............................... 5-14
............................... 5-21
............................... 5-23
vii/viii
General Information
1.1 Introduction
This section contains general information about the
Model 7014 3PChannel Thermocouple/General Purpose Multiplexer Card.
The Model 7014 card is field-installable in the Model
7001 Switch System. Since it combines the functions of
thermocouple switching and a uniform temperature
reference, it is especially useful for scanning thermocouples.
The input terminals are covered by an aluminum cover
that acts as an isothermal block to minimize temperature differences. An
transducer under the aluminum cover senses the reference (cold) junction temperature and converts it to a
proportional voltage. The cold junction temperature is
used to calculate the corrected thermocouple output.
The output voltages of each thermocouple must be
converted to temperature (“C, “F, or K) using appropriate thermocouple tables, polynomial equations, or a
multimeter capable of temperature measurements,
such as the Model 2001.
integrated
circuit temperature
The rest of Section 1 is arranged in the following man-
*fZr:
Features
1.2
Warranty information
1.3
Manual addenda
1.4
Safety symbols and terms
1.5
Specifications
1.6
Unpacking and inspection
1.7
Repacking for shipment
1.8
Optional accessories
1.9
1.2 Features
The Model 7014 is a low voltage, two-pole, quad, 1 x 10
multiplexer card. Some of the key features include:
Low contact potential and offset current for mini-
l
mal effects on low-level signals.
In addition, any channel can be used for monitoring
low-level signals. The Model 7014 uses 2-p& Form A
contacts for switching of DC signals up to llOV, lA,
30VA (resistive load), and AC signals up to 125V RMS
or 175V peak, lA, 60VA (resistive load).
The connector board detaches from the relay
l
allowing easy access to the screw terminals and
jumpers.
l Easy jumper configuration of one, two,
four multiplexer banks.
three or
board
l-l
l Backplane jumpers. Cutting jumpers disconnects
multiplexer bank outputs from the Model 7001 analog backplane.
The CAUTION heading used in this manual explains
hazards that could damage the multiplexer card. Such
damage may invalidate the warranty.
1.3 Warranty information
Warranty information is located on the inside front
cover of this instruction manual. Should your Model
7014 require warranty service, contact the Keithley representative or authorized repair facility in your area for
further information. When returning the multiplexer
card for repair, be sure to fill out and include the service
form at the back of this manual in order to provide the
repair facility with the necessary information.
1.4 Manual addenda
Any improvements or changes concerning the multi-
plexer
hum included with the card. Addenda are provided in
a page replacement format. Simply replace the obsolete
pages with the new pages.
card or manual will be exulained in an adden-
1.6 Specifications
Model 7014 specifications are found at the front of this
manual. These specifications are exclusive of the multiplexer mainframe specifications.
1.7 Unpacking and inspection
1.7.1 Inspection for damage
The Model 7014 is packaged in a re-sealable, anti-static
bag to protect it from damage due to static discharge
and from contamination that could degrade its uerformance. Before removing the card from the bag, observe
the following precautions on handling.
Handling Precautions:
1. Always grasp the card by the side edges and shields.
Do not touch the board surfaces or components.
1.5 Safety symbols and terms
The following symbols and terms may be found on an
instrument or used in this manual.
The A
user should refer to the operating instructions located
in the instruction manual.
The
voltage may be present on the terminal(s). Use standard safety precautions to avoid personal contact with
these voltages.
The WARNING heading used in this manual exulains
dangers that might res& in personal injury or heath.
Always read the associated information very carefully
before performing the indicated procedure.
symbol on an instrument indicates that the
symbol on an instrument shows that high
2. When not installed in a Model 7001 mainframe,
keep the card in the anti-static bag and store it in the
original packing carton.
After removing the card from its anti-static bag, inspect
it for any obvious signs of physical damage. Report
any such damage to the shipping agent immediately.
1.7.2 Shipping contents
The following items are included with every Model
7014
order:
l Model 7014 39.Channel Thermocouple/General
Purpose Multiplexer Card
l Model 7014 Instruction Manual
l Additional accessories as ordered,
1-2
1.7.3 Instruction manual
The Model 7014 Instruction Manual is three-hole
drilled so that it can be added to the three-ring binder
of the Model 7001 Instruction Manual. After removing
the plastic wrapping, place the manual in the binder
following the mainframe instruction manual. Note that
a manual identification tab is included and should precede the multiplexer card instruction manual.
Advise as to the warranty status of the thermocouple card.
Write AlTENTION REPAIR DEPARTMENT on the
shipping label.
Fill out and include the service form located at the
back of this manual.
If an additional instruction manual is required, order
the manual package, Keithley part number 7014-901-
00. The manual package includes an instruction manual and any pertinent addenda.
1.7.4 Repacking for shipment
Should it become necessary to return the Model 7014
for repair, carefully pack the unit in its original packing
carton or the equivalent, and include the following information:
1.8 Optional accessories
The following accessories are available for use with the
Model 7014:
Model 7014-ST-This isothermal screw terminal con-
nector card is identical to the one provided with the
Model 7014 assembly. An extra connector card allows
you to wire a second test system.
Model 7401 - This thermocouple wire kit includes
30.5m (100 ft.) of type K (chromcl-alumcl) thcrmocouple wire.
l-3
1-4
2
Multiplexing Basics
2.1
This section covers the basics for multiplex switching
and is arranged as follows:
2.2
2.3
2.4
2.5
Introduction
Thermocouple measurement basics: Describes
the theory of thermocouple measurements and a
measurement procedure.
Basic multiplexer configurations: Covers the basic multiplex configurations; quad 1 x 10 configuration, dual 1 x 20 configuration and single 1 x
40 configuration. The significance of the backplane jumpers is also covered here.
Typical multiplexer switching schemes: Ex-
plains some of the basic ways a multiplexer can
be used to source or measure. Covers single-ended switching, differential (floating) switching
and sensing.
Multiplexer expansion: Discusses the various
configurations that are possible by using multiple cards.
Cold junction-The junction that is held at n stable
known temperature. Also known as the reference junction.
Hot junction -The junction of two dissimilar metals
that is used to measure an unknown temperature. Also
known as the measurement junction.
Isothermal block or cover- The metal block or cover
that equalizes the temperature of thermocouple connections on a switching card.
Reference accuracy
sensor and channel inside the isothermal environment.
Also known as temperature offset.
Reference channel - The channel that measures the
temperature of the isothermal environment.
Reference output -The output signal that represents
the temperature of the reference channel. Commonly
specified by a temperature coefficient of wV/“C and an
offset voltage in millivolts at 0°C.
- The maximum error between
2.2
2.2.1 Definitions
The following terms are defined as they relate to thermocouple circuits and thermocouple switching cards:
Thermocouple measurements
2.2.2
A thermocouple is a junction formed between two dis-
similar metals. If the temperature of the thermocouple
junction connected to the Model 7014 is T, a voltage E
is developed between leads A and B as shown in Figure
2-1. When connected to a voltmeter, two more junctions (C and D) are formed with the meter terminals,
Theory
which are usually copper. The measured voltage is proportional to the difference between temperatures Tand
T7.
Fi@~re 2- 1
Thermocouple measurement
To determine the difference, the thermoelectric properties of the thermocouple are needed. Data is available
to determine the voltage Y~~-SLIS temperature relationship based on a reference temperature (T1) of 0°C.
Thus, if the thermocouple-to-copper junctions were
maintained at O”C, it would be possible to determine T
by referring to the Thermocouple Reference Tables.
(See NIST Monograph 125). The tables list temperature
as a function of the meter reading E,. Since these junctions are not OT, a voltage E, is inhoduced, where:
+54.63mV at O”C, convert the voltage reading to
temperature (TI) with the formula:
T, = (El - 54.63mV) / 0.2mV per “C
T, represents the temperature of the Model 7014
isothermal connections.
2.
Using the thermocouple look-up tables or the following formula, convert the temperature (T,) from
step 1 to a voltage. Use tables matching the type of
thermocouple connected to the Model 7014. E, COTresponds to the reference voltage that would result
if an actual thermocouple were used as a reference
junction.
E, = a0 + a,T + a,F + a,T3 + a,T4
3.
Make a measurement of the voltage (E,) developed
by the thermocouple connected to the Model 7014.
4.
Add the reference voltage derived in step 2 to the
thermocouple voltage measured in step 3.
E = E, + E,
5.
Convert the voltage sum (E) from step 4 to a temperature (T) using either thermocouple look-up tables or the formula:
E, = E - E,
2.2.3 Measurement procedure
The temperature of a thermocouple junction is determined by the following summarized procedure:
l Measure the reference voltage (E,).
. Calculate the reference temperature (TI).
. Determine the reference correction voltage (E,).
l Measure the thermocouple voltage (E,).
l Calculate the thermocouple correction voltage (E).
l Determine the thermocouple temperature (T).
The complete step-by-step procedure follows:
1. Read the voltage (E,) developed by the Model 7014
reference junction. Assuming a temperature coefficient of +2OOpV/“C, and an offset voltage of
T = a, + a,E + a,E2 + a,E” + a4E4
The values for a, through a4 for the supported thermocouples are listed in tables located in Appendix A.
2.2.4 Measuring example
A measurement setup uses a Type J thermocouple. The
voltage developed by the reference junction (channel 1)
is 61.83mV. The voltage read from the thermocouple is
14476pV.
1. Find the temperature of the isothermal connections. The voltage from the reference sensor is
61.83mV
(61.83mV - 54.63mV) / 0.2mV per “C = 36°C
Using the appropriate formula or thermocouple
look-up tables (see Table 6.32 of NIST Monograph
125), find the equivalent voltage developed by a
Type J thermocouple at 36°C. This voltage is found
to be 1849.11iv. The formula shown in Step 2 above
would yield 1849.085cLv.
2-2
3. The voltage developed by the thermocouple is
measured as 14476vV.
4.
The sum of the voltage is 14476 + 1849.1, or
16325.1pV.
5. Using the appropriate formula or thermocouple
look-up tables (see Table A6.2.1 of NIST Monograph 125), find the temperature for a Type J thermocouple corresponding to 16325.1pV. This
temperature is 3OO.O”C. The formula shown in step
5 above would yield 299.995%
NOTE
A multimeter with a temperature
function, such as a Keithley Model
2001, will perform the measurement
procedure automatically, except for
closing and opening channels on cxternal cards.
2.3
A simplified schematic of the Model 7014 Thermocouple Card is shown in Figure 2-2. It is organized as four
1 x 10 multiplexer banks. Each bank has 10 inputs and
one output. (Note that Input 1 of Bank A is the reference junction.) Two-pole switching is provided for
each multiplexer input, with HI and LO switched. Two
or more banks can bc jumpered together to expand
multiplexer inputs, and backplane jumpers provide
bank connections to n second card installed in a Model
Basic multiplexer configurations
Fi@we 2-2
Model 7014 simplified schematic
2.3.1 Multiplexer bank-to-bank jumpers
plexer configurations include:
NOTE
When mixing applications on a Model
7014 card, bank jumpers can be removed to isolated different signal levels. However,
switching different
levels simultaneously may affect the
card’s reference accuracy.
Jumpers are installed on the connector card to connect
multiplexer banks together to form a multiplexer of 1 x
39. Each jumper set connects two adjacent banks together. These jumper sets are included with the Model
7014.
The bank-to-bank jumpers allow you to configure the
multiplexer card in a variety of ways. Typical multi-
Reference
Junction
Bank A
1
= ,‘I ; ;f---h+OutputA
ioc ,’
m Four 1 x 10 multiplexers; no jumpers installed (Fig-
ure 2-3).
l Two 1 x 20 multiplexers; Bank A jumpered to Bank
B, Bank C jumpered to Bank D (Figure Z-4).
l One 1 x 40 multiplexer; all bank-to-bank jumpers
installed (Figure 2-5).
Other combinations are possible, including multiplex-
ers of various sizes (in multiples of 10 channels). For
example, you could install jumpers to configure the
card as one 1 x 30 and one 1 x 10 multiplexer.
Refer to Section 3 for information on installing bank-tobank jumpers.
1* ,’
Bank C
10. ,’
1. ,’
Bank D
10. ,’
Figure 2-3
Four 1 x 10 multiplexer configuration (jumpers not installed)
2-4
Reference
Junction
Bank A
Inputs
la
- ‘1: ; ;--+.y+O”tp”tA
10* ,
1. ,j2
Bank B
10. ,,2
1. ,z2
Bank C
10. /2
Bank D
Figure 2-4
Two 1 x 20 multiplexer configuration (jumpers installed)
.
.
l
.
.
l
output c
Bank B
Bank C
Bank D
I.- ,j2
10. ,,z
1. ,f2
IO. ,z2
1* ,,2
10. ,j2
Jumpers
Jumpers
Jumpers
2-5
2.3.2 Backplane jumpers
NOTE
When mixing applications in a Model
7001 mainframe, backplane jumpers
on 701X-series cards can be removed
to isolate different signal levels. However, switching different levels simultaneously may affect the card’s
reference accuracy.
There are four pairs of backplane jumpers located on
the relay card. With the jumpers installed, the banks of
Model 7001
the multiplexer card are connected to the analog backplane of the Model 7001 allowing expansion with a second 701X-series card installed in the mainframe. With
the jumpers removed (cut), the multiplexer card is isolated from another card installed in the mainframe.
The three-pole analog backplane of the Model 7001
mainframe is shown in Figure 2-6. Through this analog
backplane the banks of a Model 7014 multiplexer card,
installed in one slot, can be connected to the banks (or
rows) of a compatible card installed in the other slot of
the mainframe.
Card 1 Card 2
:
I
H> I<H
L\!PI’L
G-I’=
I I
I I
H>I
L\IPl’L
G-G
I
“? P
L! P
=>I
I
I
H>I
4 IL
=>I
L
Analog
Backplane
Row 1 or Bank A
ROW 2 or Bank B
ROW 3 oi Bank c
ROW 4 or Bank 0
r----l
I
KH
I
<G
I<”
G
I
Lee---------.
Figure 2-6
Model 7001 analog backplane
2-6
Figure 2-7 shows how each bank of the Model 7014 is
connected to the backplane. Notice that since the Model 7014 is a two-pole card, there is no connection made
to the Guard terminal of the backplane. The Model
7014 is shipped from the factory with the backplane
jumpers installed.
ries cards. As a result, any of these
cards installed in one slot in the mainframe is electrically isolated from
any
card installed in the other slot. The
only way to connect a Model 7014 to
one of these cards is to wire them together.
7014
Bank
(1 Of 4)
H‘A.) H
L-J::
H = High
L=Lmv
G = Guard
Figure2-7
Bank connections to backplane
Backplane
.l”fllp~~S
+
>
L
G
<
<
<
Removing (cutting) the backplane jumpers isolates the
card from the backplane, and subsequently, any card
installed in the other slot. For information on removing
the jumpers, refer to Section 3.
NOTE
The Model 7001 does not provide an
analog backplane for the non-701X se-
2.4 Typical multiplexer switching
schemes
The following paragraphs describe some basic switching schemes that are possible with a two-pole switching multiplexer. These switching schemes include
some various shielding configurations to help minimize noise pick up in sensitive
tions. These shields are shown connected to chassis
ground. For some test configurations, shielding may
prove to be more effcctivc connected to circuit common. Chassis ground is accessible at thr rear panel of
the Model 7001.
2.4.1 Thermocouple switching
In a typical switching configuration for thermocouples,
all banks on the Model 7014 are connected together. As
shown in Figure 2-7, the voltage
is connected to one of the card outputs, and up to 39
thermocouples arc connected to the inputs.
measurement applica-
measuring instrument
Figure2-8
Thermocouple switching example
input 2-40
4,
In
+t-------
Thermocouple
>
2-7
2.4.2 Single-ended switching 2.4.3 Differential switching
In the single-ended switching configuration, the source
or measure instrument is connected to the DUT
through a single pathway as shown in Figure 2-9. The
instrument is connected to the output of one of the
banks and the DUT is shown connected to one of the
inputs for that bank.
The differential or floating switching configuration is
shown in Figure Z-10. The advantage of using this con-
figuration is that the terminals of the SOUIC~ or measure
instiument are not confined to the same pathway. Each
terminal of the instrument can be switched to any
available input in the test system.
* Optional
Shield
Note: There are no user connections for the
reference junction (Bank A, Input 1).
Figure 2-9
Sing/e-ended switching example
Figure 2- 10
Differential switching example
Note: There are no user connections for the
reference junction (Bank A, Input 1).
2-E
2.4.4 Sensing 2.4.5 SMU connections
Figure 2-11 shows how the multiplexer card can be
configured to use instruments that have sensing capa-
bility The main advantage of using sensing is to cancel
the effects of switch card path resistance (<la) and the
resistance of external cabling. Whenever path resistance is a consideration, sensing should be
used.
Bank C, D
Figure 2-12 shows how to connect a Keithley Model
236,237 or 238 Source Measure Unit to the multiplexer
card. By using triax cables that are unterminated at one
end, the driven guard and chassis ground are physically extended all the way to thr card.
7 ^
Input i-10
Input I-IO
Note: There are no user connections for the
reference junction (Bank A, Input 1).
Figure 2- 11
Sensing example
2-9
Bank A, B I
ZEZP
7014
Input l-10
In
DUT
I”
Input l-10
Note: There are no user connections for the
reference junction (Bank A, Input 1).
WARNING : Hazardous voltages may be preSe”t on
Figure 2-
SMU connections
12
GUARD. Make sure all cable shields are
properly insulated before applying power.
2.5 Multiplexer expansion
With the use of additional switching cards and mainframes, larger systems can be configured. Each Model
7001 Switch System mainframe will accommodate up
to two cards, and up to six mainframes can be connected together. Thus, a switch system using as many as 12
cards can be configured.
NOTE
When mixing applications in a Model
7001 mainframe, backplane jumpers
on 701X.series cards can be removed
to isolate different signal levels. However, switching different levels simultaneously may affect the card’s
reference accuracy.
Separate switching systems
2.5.1 Two-card switching systems
Each Model 7001 Switch System mainframe can accommodate two cards to allow the following switching
configurations.
2-l 0
Two single-card systems can be configured by removing the backplane jumpers from one of the cards. The
two cards will be controlled by the same mainframe,
but they will be electrically isolated from each other.
Figure 2-13 shows an example using two Model 7014
multiplexer cards.
Four 1x10 Multiplexers
Card 2
L---------------_
Four 1x10 Multiplexers
\
Backplane
.hmpers
FbXllO”C3d
Multiplexer input expansion
You can double the number of multiplexer inputs by
simply installing two “as shipped” Model 7014s in the
Model 7001 mainframe. By leaving the backplane
jumpers installed, the banks of the multiplexer card installed in slot 1 (CARD 1) are automatically connected
to the banks of the multiplexer card installed in slot 2
(CARD 2) through the analog backplane.
Figure 2-14 shows an example of input expansion.
Each Model 7014 card is configured as four 1 x 10 multiplexers. By connecting the banks together (via Model
7001 analog backplane), the resultant multiplexer system has 20 inputs for each of the four banks. Notice
that if all the bank-to-bank jumpers (for both cards)
were installed, the result would be a single 1 x 80 multiplexer.
Mixing card types
Different types of cards can be used together to create
some unique switching systems. For example, you
could have a Model 7014 multiplexer card installed in
one slot and a Model 7012 matrix card installed in the
other slot.
Figure Z-15 shows a possible switching system using a
matrix card and a multiplexer card. The backplane
jumpers for both the matrix and multiplexer cards
must be installed. This allows matrix rows to
be con-
nected to multiplexer banks. On the multiplexer card,
the bank-to-bank jumpers must be removed to maintain isolation between matrix rows. See the instruction
manual for the Model 7012 for complete information
on the matrix card.
2.5.2 Mainframe multiplexer expansion
Multiplexer systems using up to 12 multiplexer cards
are possible if you USE six Model 7001 mainframes together. Each Model 7014 added to the system provides
39 additional inputs. Paragraph 3.4.3 explains how to
connect a test system using two mainframes.
2.11
r----
Card 1 Backplane
---------_____
7cm Analog
Card 2
r-------------
Quad 1x10 Multiplexers
Figure 2- 14
Mu/t&her input expansion example
Quad
1x20 Multiplexer
---------_____
Quad 1 xl 0 Multiplexers
I
L--------------2
Figure 2- 15
Mixed card type example
2-12
4 x 10 Matrix
/<I 1 I ( I I II I IBank /
L----------------~
Quad 1 x 10 MUX
3
Card Connections & Installation
3.1 Introduction
WARNING
The procedures in this section are intended only for qualified service per-
t3OIUId.
procedures unless qualified to do so.
Failure to recognize and observe normal safety precautions could result
in personal injury or death.
The information in this section is arranged as follows:
3.2 Handling precautions: Explains precautions that
must be followed to prevent contamination to the mul-
tiplexer card assembly. Contamination could degrade
the performance of the multiplexer card.
3.3
Connections: Covers the basics for connecting
external circuitry to the isothermal screw terminal connector card.
Do not perform these
3.2 Handling precautions
To maintain high impedance isolation, care should be
taken when handling the relay card to avoid contamination from such foreign materials as body oils. Such
contamination can substantially lower leakage resistances, thus degrading performance.
To avoid possible contamination, always grasp the relay and connector cards by the side edges or shields.
Do not touch the board surfaces or components. On
connectors, do not touch areas adjacent to the electrical
contacts. Dirt build-up over a period of time is another
possible source of contamination. To avoid this problem, operate the mainframe and multiplexer card in n
clean environment.
If a card becomes contaminated, it should be thoroughly cleaned as explained in paragraph 5.2.
3.4 Typical connection schemes: Provides some typical connection schemes for single card, two-card and
two-mainframe system configurations.
3.5 Model 7014 installation: Provides a procedure to
install the multiplexer card assembly in the Model 7001
mainframe.
3.3 Connections
This paragraph provides the basic information needed
to connect your external test circuitry to the multiplexer card. It includes the installation of the bank-to-bank
jumpers on the connector card, installation/removal of
backplane jumpers on the relay card, and detailed in-
formation on making external connections to the con-
nector card.
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