National Instruments SCXI -1314 User manual

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trademarks or trade names of their respective companies.
322859A-01 ©Copyright 2000 National Instruments Corp. All rights reserved. August 2000
INSTALLATION GUIDE
SCXI -1314 UNIVERSAL STRAIN TERMINAL BLOCK
This guide describes how to install and use the SCXI-1314 terminal block
with your SCXI-1520 module.
Introduction
The SCXI-1314 terminal block is used with the SCXI-1520 universal
strain/bridge module enabling you to conveniently connect strain gauges
through screw terminals. There are 88 screw terminals arranged in eight
groups of 11. Each group corresponds to one of the eight channels available
on the SCXI-1520. (Refer to Figure 2 for a diagram of terminal locations.)
The signal names of the terminals for each channel are listed in Table 1.
Each channel input contains screw terminals that connect to the inputs of
the SCXI-1520, two precision 100 kΩshunt calibration resistors, and a
precision quarter-bridge completion resistor. The SCXI-1520 contains
Table 1. Signal Names
Signal Name Condition
P+ Positive excitation signal
P– Negative excitation signal
S+ Positive input signal
S– Negative input signal
QTR Quarter-bridge completion resistor connection
RS+ Positive remote sense signal
RS– Negative remote sense signal
SCA
(2 terminals)
Shunt calibration A signal
SCB
(2 terminals)
Shunt calibration B signal
™

SCXI-1314 Universal Strain Terminal Block 2 ni.com
relays that switch the resistors in and out of the input circuit to provide
shunt calibration and quarter-bridge completion.
The quarter-bridge completion resistor has a factory default value of 350 Ω
for use with a 350 Ω strain gauge. These resistors are placed in sockets on
the terminal block so you can easily replace them with resistors suitable to
your specific strain gauge. If your application requires a 120 Ω strain
gauge, use the eight 120 Ωresistors included in the kit.
For a complete description of the use and operation of the SCXI-1520
module, refer to the SCXI-1520 User Manual.
What You Need to Get Started
To install and use your SCXI-1314 terminal block, you need the following
items:
❑SCXI-1314 terminal block
❑SCXI-1314 Universal Strain Terminal Block Installation Guide
❑Eight precision 120 Ωresistors for use in quarter-bridge completion
circuits (if using 120 Ωstrain gauges)
❑SCXI chassis
❑SCXI-1520 module
❑SCXI-1520 User Manual
❑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-1314 Universal Strain Terminal Block
Connecting the Signals
To connect the signal to the terminal block, perform the following steps,
referring to Figures 1 and 2 as necessary:
Figure 1. SCXI-1314 Parts Locator Diagram
1. Unscrew the top cover screws and remove the top cover.
2. Loosen the strain-relief screws and remove the strain-relief bar.
3. Run the signal wires through the strain-relief opening. You can add
insulation or padding if necessary.
4. Prepare your signal wire by stripping the insulation no more than
7 mm.
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 a
short circuit that can cause circuit failure.
When connecting your signals to the SCXI-1314, follow the labeling
on the SCXI-1314, as indicated in Figure 2.
1 Top Cover Screws
2 Top Cover
3 Thumbscrew
4 Mating Connector
5 Strain-Relief Bar
6 Strain-Relief Screws
7 Safety-Ground
Lug
2
7
1
4
3
5
6

SCXI-1314 Universal Strain Terminal Block 4 ni.com
Figure 2. SCXI-1314 Signal Connections
6. Tighten the terminal screws to a torque of 5 to 7 in.-lb.
7. Reinstall the strain-relief bar and tighten the strain-relief screws.
8. Reinstall the top cover and tighten the top cover screws.
9. Connect the terminal block to the module front connector as explained
in the Installing the Terminal Block section.
1 Safety Ground Lug
2 Cable Strain Relief
3 Serial Number
4 Assembly Number
5 Screw Terminal and Associated Resistors
for <CH0...CH7>
6 Shunt Calibration B Resistors, 8 places
(Factory Default = 100 kΩ,0.1%)
7 Shunt Calibration A Resistors, 8 places
(Factory Default = 100 kΩ, 0.1%)
8 Quarter-Bridge Completion Resistor, 8 places
(Factory Default = 350 Ω, 0.1%)
R1
RPJ
R2
R3
UJ
SCB SCB SCB SCB
SCA SCA SCA SCA
QTR QTR QTR QTR
SCBSCAQTR SCBSCAQTR SCBSCAQTR SCBSCAQTR
J2 J3 J4 J5
SCXI-1314
S/N
J6 J7 J8 J9
J1
C2
R4
C3
ASSY187212A-01
Q1
UNIVERSAL STRAIN
CH0 CH1 CH2 CH3 CH4 CH5 CH6 CH7
1 2 3 4
R1
RPJ
R2
R3
UJ
SCB SCB SCB SCB
SCA SCA SCA SCA
QTR QTR QTR QTR
SCBSCAQTR SCBSCAQTR SCBSCAQTR SCBSCAQTR
J2 J3 J4 J5
SCXI-1314
S/N
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
SCB
SCB
SCA
SCA
P–
S–
RS–
P+
QTR
S+
RS+
J6 J7 J8 J9
J1
C2
R4
C3
ASSY187212A-01
Q1
UNIVERSAL STRAIN
CH0 CH1 CH2 CH3 CH4 CH5 CH6 CH7
6
5
7
8

©National Instruments Corporation 5 SCXI-1314 Universal Strain Terminal Block
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.
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-1314 see the SCXI-1314
Universal Strain 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.
Electrical
Accuracy of resistors
120 Ω completion resistor............... ±0.1%
350 Ωcompletion resistor............... ±0.1%
100 kΩshunt calibration resistor.... ±0.1%
Temperature coefficient of resistors
120 Ω completion resistor............... ±10 ppm/°C
350 Ωcompletion resistor............... ±10 ppm/°C
100 kΩshunt calibration resistor.... ±10 ppm/°C

SCXI-1314 Universal Strain Terminal Block 6 ni.com
Mechanical
Resistor sockets
Mating lead size...............................0.023 to 0.026 in.
Mating lead length...........................0.110 to 0.175 in.
Lead spacing....................................0.500 in.
Environment
Operating temperature ............................0 to 50 °C
Storage temperature................................–20 to 70 °C
Relative humidity ...................................10 to 90%
Indoor use only