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TBX-1329 Installation Guide

6

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Configuring AC/DC Coupling

Each channel of the TBX-1329 has two switches you can use to switch
from AC to DC; thus, you can configure each channel individually.
The factory-default setting for the switches is the DC position so that the
terminal block passes all signals, DC and AC, to the SCXI module. In the
AC position, the switches switch in a capacitor and, depending on which
module you use, a referencing resistor. This blocks the DC components
of the input signal and provides a true AC signal to the SCXI module.
Each switch is uniquely marked to make switch identification easier.
Each switch that switches the capacitor into the circuit is labeled with SC

X

.

Each switch that switches the resistor into the circuit is labeled with SR

X

.

The

X

symbol represents the channel number; for example, SC2 is the

capacitor switch for channel 2 and SR2 is the resistor switch for channel 2.
Table shows the TBX-1329 terminal block switch settings.

Table 2.

TBX-1329 Terminal Block Switch Settings

Switch Settings for

Each Channel

Description

Switch Configuration

SCXI-1120,
SCXI-1121,

SCXI-1125, and

SCXI-1126

SCXI-1120D

DC coupling selected; removes
capacitor and resistor from the
circuit. Signals go straight
through.

Switch both

SCX

and

SRX

switches

for DC coupling.

Switch both

SCX

and

SRX

switches

for DC coupling.

AC coupling selected;

SCX

connects the capacitor to the
circuit.

SRX

connects the resistor

to the circuit.

Switch both

SCX

and

SRX

switches

for AC coupling.

Switch

ONLY

SCX

switch for

AC coupling.

SRX

must be in the DC
position.

DC

AC

SCX

SRX

DC

AC

SCX

SRX

Summary of Contents for TBX-1329

Page 1: ... 1125 or SCXI 1126 front connector The TBX 1329 mounts on most European standard DIN EN mounting rails The terminal block has 16 screw terminals for easy connection Two screws are provided to connect to the SCXI functional earth terminal through the SH32 32 A cable shield With the SCXI 1120 SCXI 1120D SCXI 1125 or SCXI 1126 the remaining eight pairs of screw terminals connect signals to the eight ...

Page 2: ... 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 Safety Infor...

Page 3: ...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 terminal...

Page 4: ...X 1329 across the excitation outputs provided on the SCXI 1121 To reduce errors in your output voltage first you need to calculate the voltage drop across the SH32 32 A cable This voltage drop which results in an error in your measurement depends on the cable length and on the strain gauge value and configuration The SH32 32 A cable has a resistance of 0 21 Ω m To determine the amount of error int...

Page 5: ...mpensating is to calculate the lead resistance as shown in Steps 1 through 3 then input it along with your other strain gauge parameters into the conversion formula in your National Instruments data acquisition software packages In order to minimize resistive compensation locate the load closer to your SCXI module by using shorter cable lengths or use heavy gauge wire to connect to the TBX 1329 Me...

Page 6: ...X Each switch that switches the resistor into the circuit is labeled with SRX The X symbol represents the channel number for example SC2 is the capacitor switch for channel 2 and SR2 is the resistor switch for channel 2 Table 2 shows the TBX 1329 terminal block switch settings Table 2 TBX 1329 Terminal Block Switch Settings Switch Settings for Each Channel Description Switch Configuration SCXI 112...

Page 7: ...ling Figure 1 TBX 1329 Parts Locator Diagram To connect the signal to the terminal block perform the following steps while referring to Figure 2 1 Remove the TBX 1329 terminal block cover by unscrewing the four captive cover screws in the cover corners These screws stay attached to the cover without falling out 1 Current Loop Receiver Resistor 2 Safety Ground Solder Lugs 3 Product Name 4 Assembly ...

Page 8: ...ully into the terminals 4 Tighten the terminals to a torque of 5 7 in lb 56 79 Newton cm 5 Relieve strain on your signal wires by tie wrapping them to the mounting rails of your rack 6 Replace the TBX 1329 terminal block cover and tighten the captive cover screws Figure 2 TBX 1329 Parts Locator Diagram 1 Safety Ground Lugs 2 Captive Cover Screws 3 Terminal Block Connector 4 Signal Wire Entry 2 1 4...

Page 9: ... and Terminal Block Perform the following steps to mount the SH32 32 A cable assembly and connect the TBX 1329 to your SCXI module Refer to Figures 3 through 5 as needed 1 Turn off your SCXI chassis 2 Turn off the computer that contains your data acquisition DAQ device or disconnect the device from your SCXI chassis 3 Connect the TBX cable adapter to the appropriate SCXI module and secure it by ti...

Page 10: ...329 Installation Guide 10 ni com Figure 3 Connecting the SH32 32 A Cable to the SCXI Module 1 Backshell Mounting Screws and Ears 2 Cable Assembly 3 Thumb Screws 4 SCXI Chassis 5 TBX Cable Adapter 3 2 4 3 5 1 ...

Page 11: ...the other end of the cable assembly to your TBX 1329 terminal block connector and secure the SH32 32 A cable by tightening both backshell mounting screws 7 Reconnect the DAQ device to your SCXI chassis 1 Backshell Mounting Screws and Ears 2 Safety Ground Lugs 3 Captive Cover Screws 4 Terminal Block Connector 5 Signal Wire Entry Note The SH32 32 A cable is not shown in the exact position for proper...

Page 12: ... Rack Mount Installation Guide for instructions If you are not using this rack mount assembly perform the following steps to mount the TBX assembly directly onto your DIN rail 1 Snap the TBX terminal block onto the DIN rail with a firm push 2 Install the SCXI chassis using the appropriate chassis rack mount kit Note To remove the TBX terminal block from the DIN rail place a flathead screwdriver in...

Page 13: ...250 VDC Input impedance minimum Between CH or CH terminals 2 MΩ Between CH or CH terminal and ground 1 MΩ Current receiver resistors Resistors included none Resistor sockets 8 pairs Maximum current 20 mA Maximum working voltage signal common mode Channel to ground Each channel must remain within 300 Vrms or 300 VDC of ground Channel to channel Each channel must remain within 300 Vrms or 300 VDC of...

Page 14: ...earth ground 2 lugs Mechanical Dimensions 12 7 by 7 62 by 11 16 cm 5 by 3 by 4 4 in Weight 100 gm 3 5 oz Compatible DIN rails DIN EN 50 022 DIN EN 50 035 Environmental Operating temperature 0 to 50 C Storage temperature 20 to 70 C Relative humidity 10 to 90 noncondensing Altitude maximum 2000 m Safety Designed in accordance with IEC 61010 1 UL 3111 1 and CAN CSA C22 2 No 1010 1 for electrical meas...

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