Tektronix 7710 Users Guide
Model 7710 Multiplexer Card
User’s Guide
PA-847 Rev. B / 8-03
A GREATER MEASURE OF CONFIDENCE
.
Safety Precautions
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 manual for complete product specifications.
If the product is used in a manner not specified, the protection provided by the product may be impaired.
The types of product users are:
Responsible body
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
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
to keep it operating properly, 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 perform them. Otherwise, they should be performed only by
service personnel.
Service personnel
safe installations and repairs of products. Only properly trained service personnel may perform installation and service procedures.
Keithley 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 overvoltages. 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 Manual.
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.
that hazardous voltage is present in any unknown circuit before
measuring.
is the individual or group responsible for the use
use the product for its intended function. They must be
perform routine procedures on the product
are trained to work on live circuits, and perform
A good safety practice is to expect
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 1000 volts,
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, make sure 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 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.
no conductive part of
5/03
If a screw is present, connect it to safety earth ground using the
wire recommended in the user documentation.
!
The symbol on an instrument indicates that the user should refer to the operating instructions located in the manual.
The symbol on an instrument shows that it can source or measure 1000 volts or more, including the combined effect of normal
and common mode voltages. Use standard safety precautions to
avoid personal contact with these voltages.
The symbol indicates a connection terminal to the equipment
frame.
The
WARNING
result in personal injury or death. Always read the associated information very carefully before performing the indicated procedure.
The
CAUTION
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.
heading in a manual explains dangers that might
heading in a manual explains hazards that could
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., 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.
n
Keithley Instruments, Inc.
28775 Aurora Road
Cleveland, Ohio 44139
(440) 248-0400
Fax: (440) 248-6168
www.keithley.com
Introduction
NOTE The Model 7710 will operate properly when installed in one of the following
The Model 7710 is a 20-channel differential multiplexer card with the following features:
Model 7710 Multiplexer Card
User’s Guide
Model 27xx instruments:
Model 2700 – Equipped with B05 (or later) firmware
Model 2701 – Equipped with A01 (or later) firmware
Model 2750 – Equipped with A04 (or later) firmware
• Fast actuating, long life solid state relays.
• DC and AC voltage measurement.
• 2-wire or 4-wire measurements (automatically pairs relays for four wire measurements —
+ 10).
• Temperature applications (RTD, thermistor, thermocouple).
• Built-in cold junction reference for TC temperature.
• Plug-in screw terminal connections.
WARNING Before operating the Model 27xx with an accessory card, verify that the card is
properly installed and the mounting screws are tightly fastened. If the mounting screws are not properly connected, an electrical shock hazard may be
present.
Topics
Operating instructions............................................................................................... page 2
Card configuration .................................................................................................... page 2
Fast scanning .......................................................................................................... page 4
Fast scan using 7710 module with Model 2701 mainframe ..................................... page 4
Operating considerations........................................................................................ page 10
Low-ohms measurements ...................................................................................... page 10
Voltage measurements .......................................................................................... page 11
Insertion loss .......................................................................................................... page 12
Crosstalk................................................................................................................. page 12
Additional errors for 27xx switch systems .............................................................. page 12
Heat sink temperature measurements ................................................................... page 13
Card handling precautions...................................................................................... page 13
Card connections.................................................................................................... page 14
Wiring procedure .................................................................................................... page 15
Typical connections ................................................................................................ page 17
Connection log........................................................................................................ page 19
Calibration .............................................................................................................. page 21
Specifications ...................................................................................... end of User s Guide
PA-847 Rev. B / 8-03
'
Operating instructions
CAUTION Before installing or removing a Model 77xx plug-in module, make sure the
Model 27xx power is turned off and disconnected from line power. Failure to
comply may result in incorrect operation and loss of Model 77xx EPROM data.
Switching card operation is covered in the Model 27xx User’s Manual. The Model 7710 operates
the same as the Model 7700 switching card with the following differences:
• The Model 7710 has no amps channel. The Model 7700 has two amps channels.
• The Model 7710 uses solid state opto-coupled FET relays. The Model 7700 uses latching
electromechanical relays. Solid state relays provide longer relay life and are up to six
times faster than the electromechanical types used in other switching modules.
WARNING The system’s maximum voltage, including other switch modules and front
panel terminals, is limited to 60V peak-to-peak AC or DC between any terminal
and chassis, or any two terminals when the 7710 is installed. Exceeding these
levels creates a shock hazard and could cause damage to the card. Complete
specifications are located at the end of this User’s Guide .
Topics
WARNING When a Model 7710 module is inserted into a Model 27xx, it is connected to
the front and rear inputs, as well as the other cards in the system, through the
instrument backplane. To prevent damaging the 7710 module or creating a
shock hazard, the entire test system and all of its inputs should be de-rated to
60V DC (42V rms).
Card configuration
Figure 1 shows a simplified schematic diagram of the Model 7710 module. As shown, the
Model 7710 has channels that are grouped into two banks of ten channels (twenty channels
total). Backplane isolation is provided for each bank. Each bank includes separate cold junction
reference points. The first bank contains channels 1 through 10, while the second bank contains
channels 11 through 20. Each channel of the 20-channel multiplexer card is wired with separate
inputs for HI/LO providing fully isolated inputs.
Connections to DMM functions are provided through the card backplane connector.
Channels 21, 22, and 23 are configured automatically by the Model 27xx when using system channel operation. However, by using multiple channel operation (refer to Section 2 of the Model 27xx
User’s Manual), they can be manually configured.
For example, assume a 7710 module is installed in slot 1 of the mainframe and an external source
is connected to Card Source input. To connect the source to channel 11 only, multiple channel
operation must be used:
Topics
ROUT:OPEN:ALL
ROUT:MULT:CLOS (@111,123) ' Close channels 11 and 23.
For the above command sequence, the Digital Multimeter (DMM) of the Model 27xx will be electrically
isolated from the test circuit.
2
Open all channels.
Topics
3
When using system channel operation for 4-wire measurements (including 4-wire ohms, RTD
temperature, Ratio, and Channel Average), the channels are paired as follows:
CH1 and CH11 CH6 and CH16
CH2 and CH12 CH7 and CH17
CH3 and CH13 CH8 and CH18
CH4 and CH14 CH9 and CH19
CH5 and CH15 CH10 and CH20
Figure 1
Simplified schematic of Model 7710
Card Source
Cold junction
Ref x3
Channel 1
(Channels 2-9)
Channel 10
Cold junction
Ref x3
Channel 11
HI
LO
HI
LO
HI
LO
Channel 23
2-Pole (Closed)
4-Pole (Open)
(see Notes)
HI
LO
Channel 21
(see Note)
Backplane
isolation
Channel 22
(see Note)
Backplane
isolation
HI
Input
LO
HI
Sense
LO
Topics
Topics
To Model
27xx
Backplane
(Channels 12-19)
HI
Channel 20
Card Sense
LO
HI
LO
Notes:
Channels 21, 22, and 23 in this schematic refer
to the designations used for control and not actual
available channels.
Channels 21 and 22 can be individually
controlled using multiple channel operation
(ROUT:MULT commands) if the module is not
to be connected to the internal DMM.
For more information, see Section 2 of the
Model 27xx User’s Manual.
Topics
Fast scanning
Fast scanning is achieved by using the 7710 module (which has high-speed solid state FET relays)
with the Model 2701 mainframe. With mainframe speed settings optimized for DCV or ohms measurements, the Model 2701 can scan approximately twice as fast as the Models 2700 and 2750.
To achieve the fastest scan possible, use the following Model 27xx mainframe settings for the
scan:
VOLT:AVER:STAT OFF
VOLT:DIG 4
VOLT:NPLC X
SYST:AZER:STAT OFF
SYST:LSYN OFF
TRIG:DEL 0
FORM:DATA ASCII ‘ Formats data as an ASCII string (N/A for 2701).
FORM:ELEM READ
CALC3:OUTP OFF
CALC3:LIM1:STAT OFF
DISP:ENAB OFF
When finished with the scan, the display can be turned back on with the following command:
‘ Disables filtering.
‘ Sets display resolution to 4.5 digits.
‘ Sets reading rate:
‘ where: X = 0.01 (2700 and 2750).
‘ X = 0.002 (2701)
‘ Disables auto-zero.
‘ Disables line synchronization.
‘ Sets trigger delay to 0 seconds.
‘ Returns each reading with units only.
‘ Disables limit outputs.
‘ Disables limit 1 test.
‘ Turns off display.
Topics
Topics
DISP:ENAB ON
‘ Turns on display.
Fast scan using 7710 module with Model 2701 mainframe
The following Visual Basic (VB) Version 6 program demonstrates using the Model 7710 card and
Model 2701 mainframe to achieve fast scanning. It makes use of WinSocket control to communicate
with the Model 7701 mainframe. This User’s Guide is provided as a PDF file on the product information CD-ROM. From Acrobat Reader, the program code can be copied and pasted into Visual Basic.
Topics
4
’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
’ 7710 DCV FAST SCAN EXAMPLE FOR THE 2701 MODULE
’
’ This program is an example of configuring a simple DCV scan on the 7710 with a 2701 mainframe.
’ This program acquires readings at a rate of 500/ sec.
’
’ Note that a Winsocket control in Visual Basic is being used to communicate with the 2701.
’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Const ScanList = "(@101:120)"
Dim TestRunning As Boolean
Dim DataReceived As Boolean
Dim DataSent As Boolean
Dim Data As String
’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
’ A Visual Basic function call when a Form (program window) is opened.
’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Private Sub Form_Load()
TestRunning = False
End Sub
Topics
Topics
’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
’ These two functions exit the program and closes the winsocket.
’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Private Sub ExitButton_Click()
Unload Me
End Sub
Private Sub Form_Unload(Cancel As Integer)
Cancel = MsgBox("Exit?", 20, "Exit Verify")
If Cancel = vbYes Then
Cancel = 0
CloseWinsocket
End If
End Sub
’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
’ This function opens the Winsocket for communication with the 2701 ethernet mainframe.
’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’
Function ConnectTo2701() As Integer
Dim Time0 As Single
Topics
5
Loading...