National Instruments SCXI-1313 User manual

CVI™, LabVIEW™, National Instruments™,ni.com
™,NI-DAQ ™, and SCXI™are trademarks of National Instruments Corporation. Product and company
names mentioned herein are trademarks or trade names of their respective companies.
322853A-01 ©Copyright 2000 National Instruments Corp. All rights reserved. October 2000
INSTALLATION GUIDE
SCXI -1313 HIGH-VOLTAGE ATTENUATOR
TERMINAL BLOCK
This guide describes how to install and use the SCXI-1313 high-voltage
attenuator terminal block with an SCXI-1125 module.
Introduction
The SCXI-1313 high-voltage attenuator terminal block is shielded and has
screw terminals that connect to the SCXI-1125 input connector. Each
SCXI-1313 channel has a precision 100:1 resistive voltage divider that you
can use to measure voltages of up to 300 Vrms or ±300 VDC with the
SCXI-1125. You can individually bypass these dividers for low-voltage
measurement applications.
The terminal block has 18 screw terminals for easy signal connection. One
pair of screw terminals connects to the SCXI-1125 chassis ground. When
used with the SCXI-1125, the remaining eight pairs of screw terminals
connect signals to the eight analog inputs.
Conventions
The following conventions are used in this guide:
»The »symbol leads you through nested menu items and dialog box options
to a final action. The sequence File»Page Setup»Options directs you to
pull down the File menu, select the Page Setup item, and select Options
from the last dialog box.
This icon denotes a note, which alerts you to important information.
This icon denotes a caution, which advises you of precautions to take to
avoid injury, data loss, or a system crash.
bold Bold text denotes items that you must select or click on in the software,
such as menu items and dialog box options.
™

SCXI-1313 Installation Guide 2 ni.com
italic Italic text denotes variables, emphasis, a cross reference, or an introduction
to a key concept. This font also denotes text that is a placeholder for a word
or value that you must supply.
monospace Text in this font denotes text or characters that you should enter from the
keyboard, sections of code, programming examples, and syntax examples.
This font is also used for the proper names of disk drives, paths, directories,
programs, subprograms, subroutines, device names, functions, operations,
variables, filenames and extensions, and code excerpts.
What You Need to Get Started
To set up and use your SCXI-1313 terminal block, you need the following
items:
❑SCXI-1313 high-voltage attenuator terminal block
❑SCXI-1313 High-Voltage Attenuator Terminal Block Installation
Guide
❑SCXI chassis
❑SCXI-1125 module
❑Number 1 and 2 Phillips-head screwdrivers
❑1/8 in. flathead screwdriver
❑Long-nose pliers
❑Wire cutter
❑Wire insulation stripper

©National Instruments Corporation 3 SCXI-1313 Installation Guide
Safety Information
Cautions Do not operate the device in an explosive atmosphere or where there may be
flammable gases or fumes.
Keep away from live circuits. Do not remove equipment covers or shields unless you are
trained to do so. If signal wires are connected to the device, hazardous voltages can exist
even when the equipment is turned off. To avoid a shock hazard, do not perform procedures
involving cover or shield removal unless you are qualified to do so and disconnect all field
power prior to removing covers or shields.
Do not operate damaged equipment. The safety protection features built into this device
can become impaired if the device becomes damaged in any way. If the device is damaged,
turn the device off and do not use it until service-trained personnel can check its safety.
If necessary, return the device to National Instruments for service and repair to ensure that
its safety is not compromised.
Do not operate this equipment in a manner that contradicts the information specified in this
document. Misuse of this equipment could result in a shock hazard.
Do not substitute parts or modify equipment. Because of the danger of introducing
additional hazards, do not install unauthorized parts or modify the device. Return the
device to National Instruments for service and repair to ensure that its safety features are
not compromised.
Yo u must insulate all of your signal connections to the highest voltage with which the
SCXI-1125 can come in contact.
When using the device with high common-mode voltages, you must insulate your signal
wires for the highest input voltage. National Instruments is not liable for any damages or
injuries resulting from inadequate signal wire insulation. Use only 26-14 AWG wire with
a minimum voltage rating of 300 V and a temperature value of 60 °C for measuring up to
300 V.
When connecting or disconnecting signal lines to the SCXI terminal block screw terminals,
make sure the lines are powered off. Potential differences between the lines and the SCXI
ground can create a shock hazard while you connect the lines.
Connections, including power signals to ground and vice versa, that exceed any of the
maximum signal ratings on the SCXI device can create a shock or fire hazard, or can
damage any or all of the boards connected to the SCXI chassis, the host computer, and the
SCXI device. National Instruments is not liable for any damages or injuries resulting from
incorrect signal connections.
If hazardous voltages (≥30 Vrms and42.4V
peak or 60 VDC) are present, you must connect
a safety earth-ground wire to the terminal block safety-ground lug, shown in Figure 1.
This maintains compliance with UL-3111-1 and IEC-61010-1 and protects against electric
shock when the terminal block is not connected to the chassis. To connect the safety earth
ground to the safety-ground lug, run an earth-ground wire from the signal source to the

SCXI-1313 Installation Guide 4 ni.com
terminal block. National Instruments is not liable for any damages or injuries resulting
from inadequate safety earth-ground connections.
Do not loosen or re-orient the safety-ground lug hardware when connecting the safety
ground wire; to do so reduces the safety isolation between the high voltage and safety
ground.
Clean the module and accessories by brushing off light dust with a soft non-metallic brush.
Remove other contaminants with a stiff non-metallic brush. The unit must be completely
dry and free from contaminants before returning it to service.
The terminal block must be used with a UL-listed SCXI chassis.
Configuring the High-Voltage Attenuator
Each channel has a 100:1 high-voltage attenuator. To enable or disable the
attenuator, either change the default configuration settings for the
SCXI-1313 in Measurement & Automation Explorer or adjust the input
limit ranges in your application. When using virtual channels, the input
limits configured in the virtual channel configurator are used to set the
attenuation circuitry appropriately.
The SCXI-1313 is factory calibrated to the specifications listed in the
Specifications section of this guide and is shipped with a calibration
certificate. The calibration EEPROM on the SCXI-1313 stores calibration
constants, which provide software correction values, that the application
development software uses to correct your measurements for gain errors in
the attenuation circuitry.
Table 1. Input Signal Range Versus Gain
Overall
Gain
Overall Voltage
Range
Module
Gain
Terminal
Block Gain
0.01 300 Vrms or VDC 10.01
0.02 ±250 Vpeak or VDC 20.01
0.05 ±100 Vpeak or VDC 50.01
0.1 ±50 Vpeak or VDC 10 0.01
0.2 ±25 Vpeak or VDC 20 0.01
0.5 ±10 Vpeak or VDC 50 0.01
1±5 Vpeak or VDC 1 1
2±2.5 Vpeak or VDC 2 1
2.5 ±2.0 Vpeak or VDC 250 0.01

©National Instruments Corporation 5 SCXI-1313 Installation Guide
Connecting Signals
Caution Refer to the Safety Information section before removing equipment covers or
connecting or disconnecting any signal wires.
To connect the signal to the terminal block, perform the following steps,
referringtoFigures1and2asnecessary:
1. Unscrew the top cover screws and remove the top cover.
2. Loosen the strain-relief screws and remove the strain-relief bar.
5±1 Vpeak or VDC 5 1
10 ±500 mVpeak or VDC 10 1
20 ±250 mVpeak or VDC 20 1
50 ±100 mVpeak or VDC 50 1
100 ±50 mVpeak or VDC 100 1
200 ±25 mVpeak or VDC 200 1
250 ±20 mVpeak or VDC 250 1
500 ±10 mVpeak or VDC 500 1
1000 ±5 mVpeak or VDC 1000 1
2000 ±2.5 mVpeak or VDC 2000 1
Table 1. Input Signal Range Versus Gain (Continued)
Overall
Gain
Overall Voltage
Range
Module
Gain
Terminal
Block Gain

SCXI-1313 Installation Guide 6 ni.com
3. Prepare your signal wire by stripping the insulation no more than
7mm.
Figure 1. SCXI-1313 Parts Locator Diagram
4. Run the signal wires through the strain-relief opening. You can add
insulation or padding if necessary.
Note When connecting your signals to the SCXI-1313, follow the labeling on the
SCXI-1313 for the appropriate module, as indicated in Figure 2.
1 Top Cover Screws
2TopCover
3Thumbscrew
4 Mating Connector
5 Strain-Relief Bar
6 Strain-Relief Screws
7 Safety-Ground Lug
2
7
1
4
3
5
6
Back View Front View

©National Instruments Corporation 7 SCXI-1313 Installation Guide
Figure 2. SCXI-1313 Signal Connections
5. Connect the signal wires to the screw terminals by inserting the
stripped end of the wire fully into the terminal. No bare wire should
extend past the screw terminal. Exposed wire increases the risk of short
circuits and equipment failure.
6. Tighten the screws to a torque of 5–7in.-lb.
7. Connect the safety earth ground to the safety-ground lug. Refer to the
Safety Information section for connection information.
8. Reinstall the strain-relief bar and tighten the strain-relief screws.
9. Reinstall the top cover and tighten the top cover screws.
10. Connect the terminal block to the module front connector as explained
in the Installing the Terminal Block section.
1 Voltage Dividers
2 Product Name
3 Chassis Ground
4 Thermistor
5 Assembly Number and Revision Letter
6 Serial Number
7 Channel Labeling for SCXI-1123
8 Channel Labeling for SCXI-1125
9 Screw Terminals
10 Relays to Enable or Bypass the Attenuator
3
1
2
9
6
8
10
7
54

SCXI-1313 Installation Guide 8 ni.com
Installing the Terminal Block
To connect the terminal block to the SCXI module front connector, perform
the following steps:
1. Connect the module front connector to its mating connector on the
terminal block.
2. Tighten the top and bottom thumbscrews on the back of the terminal
block to hold it securely in place.
Note For accurate cold-junction compensation, place the SCXI chassis away from an
extreme temperature differential.
Cleaning the Terminal Block
Clean the terminal block by brushing off light dust with a soft, nonmetallic
brush. Remove other contaminants with deionized water and a stiff
nonmetallic brush. The unit must be completely dry and free from
contaminants before returning it to service.
Calibrating the Terminal Block
For information on calibrating the SCXI-1313, see the SCXI-1313
High-Voltage Attenuator Terminal Block Calibration Procedure located
online at ni.com/calibration and follow the link for Manual
Calibration Procedures.
Specifications
All specifications are typical at 25 °C unless otherwise specified.
Compatible module
SCXI-1125.......................................8 input channels
Input range
SCXI-1125.......................................300 Vrms or VDC

©National Instruments Corporation 9 SCXI-1313 Installation Guide
Cold-junction sensor
Sensor type...................................... Thermistor
Accuracy1........................................ ±0.5 °Cfrom15to35°C
±0.9 °Cfrom0to15°C
and35to55°C
Repeatability ................................... ±0.2 °Cfrom15to35°C
Output ............................................. 1.91 to 0.65 V
from0to50°C
Maximum temperature gradient
between sensor and any terminal .... ±0.4 °C (non-isothermal)
High-voltage divider
Accuracy ......................................... ±0.06% (for 100:1 setting)
Drift................................................. 15 ppm/°C
Resistance ....................................... 1 MΩ
Attenuation ratio ............................. 100:1 or 1:1
on programmatic basis
Common-mode isolation
Channel to channel.......................... 300 Vrms or ±300 VDC
Channel to ground........................... 300 Vrms or ±300 VDC
Coupling.......................................... DC only
Field-wiring connectors
Screw terminals
Signal terminals ....................... 16 (8 pairs)
Functional ground terminals .... 2
Maximum wire gauge.............. 16 AWG
Terminal spacing ..................... 0.5 cm (0.2 in.) center-to-center
Dimensions of front entrance.......... 1.2 by 7.3 cm (0.47 by 2.87 in.)
Solder pads for
additional components .................... None
Safety earth-ground lugs................. 1
Strain relief ..................................... Strain-relief bar at
terminal-block entrance
1The temperature sensor accuracy includes tolerances in all component values, effects caused by temperature and loading, and
self-heating. Errors caused by temperature gradients between terminals and the sensor are not included in this specification.

SCXI-1313 Installation Guide 10 ni.com
Mechanical
Dimensions .............................................17.8 by 7.94 by 3.0 cm
(7.0 by 3.125 by 1.2 in.)
Weight ....................................................200 g (7 oz)
Environment
Operating temperature ............................0 to 50 °C
Storage temperature ................................–20 to 70 °C
Relative humidity ...................................10 to 90% noncondensing
Safety
Designed in accordance with IEC 61010-1, UL 3111-1, and CAN/CSA
C22.2 No. 1010.1 for electrical measuring and test equipment.
For use at altitudes up to 2000 meters.
Installation category II1
Pollution degree 2
Electromagnetic Compatibility
EMC/EMI ...............................................CE, C-Tick, and FCC Part 15
(Class A) Compliant
Electrical emissions ................................EN 55011 Class A at 10 m
FCC Part 15A above 1 GHz
Electrical immunity ................................Evaluated to EN 61326:1998,
Table 1
Note This device should only be operated with shielded cabling for full EMC and EMI
compliance. See the Declaration of Conformity for this product for any additional
regulatory compliance information.
1Category II refers to local-level power distribution, such as that provided by a standard wall outlet.

©National Instruments Corporation 11 SCXI-1313 Installation Guide
Temperature Sensor Output and Accuracy
The SCXI-1313 temperature sensor outputs 1.91 to 0.65 V from 0 to 50 °C.
Converting a Thermistor Voltage to a Temperature
National Instruments software can convert a thermistor voltage to the
thermistor temperature for the circuit diagram shown in Figure 3.
In LabVIEW, you can use the Convert Thermistor Reading VI found in the
Data Acquisition»Signal Conditioning palette. If you are using CVI or
NI-DAQ, use the Thermistor_Convert function. The VI takes the
output voltage of the temperature sensor, the reference voltage, and the
precision resistance and returns the thermistor temperature.
Alternatively, you can use the following formulas:
T(°C) = TK–273.15
where TKis the temperature in Kelvin
a= 1.295361 ×10–3
b= 2.343159 ×10–4
c= 1.018703 ×10–7
RT= resistance of the thermistor in ohms
VTEMPOUT = output voltage of the temperature sensor
where T(°F) and T(°C) are the temperature readings in degrees Fahrenheit
and degrees Celsius, respectively.
Note Use an average of a large number of samples to obtain the most accurate reading.
Noisy environments require more samples for greater accuracy.
TK
1
ab R
T
ln()cR
T
ln()
3
++[]
--------------------------------------------------------------=
RT5000 VTEMPOUT
2.5 VTEMPOUT –
--------------------------------------


,=
T°F() T°C()[]9
5
----------------------- 3 2+=

SCXI-1313 Installation Guide 12 ni.com
Reading the Temperature Sensor in LabVIEW
In LabVIEW, to read VTEMPOUT, use the address string:
obx! scy! mdz! cjtemp
You can have this channel-address string in the same channel-string array
as other channels on the same SCXI-1125 module and call it multiple times
within the same channel-string array.
For more information about channel-string arrays and the SCXI
channel-addressing syntax, see the LabVIEW Measurements Manual.
Temperature Sensor Circuit Diagram
You do not need to read this section to operate the SCXI-1313. The circuit
diagram in Figure 3 is optional information that you can use if you want
more details about the SCXI-1313 temperature sensor.
Figure 3. Temperature Sensor Circuit Diagram
4.7 k
1%
5k
0.1%
MTEMP
1
2
1
2
2
+
5k
at 25 oC
10 µF
16 V 0.1 µF
0.1 µF
–to
+5 V
2.5 V
LM 4040
2.5 V
0.1%

©National Instruments Corporation 13 SCXI-1313 Installation Guide
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