National Instruments SCC-ACC01 User Manual

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USER GUIDE
SCC-ACC01 Accelerometer Input Module
The SCC-ACC01 accelerometer (ACC) input module accepts an active accelerometer input signal, passes it through a 0.8 Hz highpass filter, amplifies it, and then passes it through a 19 kHz lowpass Bessel filter and an output buffer. The module has a fixed gain of 2, so the maximum input range is ±5 V. The SCC-ACC01 also provides a 4 mA current source for accelerometer excitation.

Conventions

The following conventions are used in this guide:
<> Angle brackets that contain numbers separated by an ellipsis represent
a range of values associated with a bit or signal name—for example, P0.<3..0>.
» 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. When this symbol is marked on the product, refer to the Read Me First: Safety and Radio-Frequency Interference document, shipped with the product, for precautions to take.
When symbol is marked on a product, it denotes a warning advising you to take precautions to avoid electrical shock.
When symbol is marked on a product, it denotes a component that may be hot. Touching this component may result in bodily injury.
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bold Bold text denotes items that you must select in software, such as menu
items and dialog box options. Bold text also denotes parameter names.
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. 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.
SC-2345 SC-2345 refers to both the SC-2345 connector block and the SC-2345 with
configurable connectors.
SCC SCC refers to any SCC Series signal conditioning module.
SCC-ACC01 Accelerometer Input Module User Guide 2 ni.com
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What You Need to Get Started

To set up and use the SCC-ACC01, you need the following items:
SC-2345/2350 with one of the following:
SCC-PWR01
SCC-PWR02 and the PS01 power supply
SCC-PWR03—requires a 7 to 42 VDC power supply
(not included)
One or more SCC-ACC01
SCC-ACC01 Accelerometer Input Module User Guide
Read Me First: Safety and Radio-Frequency Interference
SC-2345/2350 User Manual, available at ni.com
SCC Quick Start Guide, available at ni.com
SC-2345 Quick Reference Label
68-pin E Series DAQ device, documentation, and 68-pin cable
1/8 in. flathead screwdriver
Numbers 1 and 2 Phillips screwdrivers
Wire insulation strippers
NI-DAQ (current version) for Windows 2000/NT/XP/Me
Note Software scaling of measurements is not supported on the Macintosh operating
system.
© National Instruments Corporation 3 SCC-ACC01 Accelerometer Input Module User Guide
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Device Specific Information

Note For general SCC module installation and signal connection information, and
information about the SC-2350 carrier, refer to the SCC Quick Start Guide, available for download at

Installing the Module

Caution Refer to the Read Me First: Safety and Radio-Frequency Interference document
before removing equipment covers or connecting/disconnecting any signal wires.
ni.com/manuals.
You can plug the SCC-ACC01 into any analog input socket on the SC-2345. It can function as a single-stage module or as the first stage of a dual-stage signal conditioning configuration. The socket you choose determines which E Series DAQ device channels receive the SCC-ACC01 signals, as explained in the Connecting the Input Signals section.
For single-stage input conditioning, plug the SCC-ACC01 into any socket J(X+1), where X is 0 to 7, and connect the input signals to the module as described in the Connecting the Input Signals section.
If you use the SCC-ACC01 in a dual-stage configuration, the SCC-ACC01 must be the first-stage module. Plug it into any socket J(X+9) and plug the second-stage SCC into socket J(X+1), where X is 0 to 7. Connect the input signals to the SCC-ACC01 as described in the Connecting the Input Signals section. The SC-2345 connects the output signals of the first-stage SCC to the inputs of the second-stage SCC. An example of dual-stage conditioning is an SCC-ACC01 followed by a lowpass filter module (SCC-LPXX).
Although not available for the SCC-ACC01, sockets J9 to J16 are available for digital input/output conditioning or control with another SCC module. Refer to the SC-2345/2350 User Manual for more information on configuring, connecting, and installing SCC modules.

Connecting the Input Signals

Note The signal names have changed. Refer to ni.com/info and enter rdtntg to
confirm the signal names.
Each screw terminal is labeled by pin number <1..4>. Pins 1 and 2 form a differential (DIFF) analog input channel for measuring the voltage across the accelerometer. This channel is routed to E Series DAQ device channel X, where X is 0 to 7 depending on the socket where you plug in the SCC-ACC01. Pins 3 and 4 carry the 4 mA constant-current excitation source. Figure 1 shows the SCC-ACC01 signal connections.
SCC-ACC01 Accelerometer Input Module User Guide 4 ni.com
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ACC
The signal source can be floating or ground-referenced. The SCC-ACC01 input circuitry includes high-impedance bias resistors typically required for floating sources. External bias resistors connected to ground are not required.
For floating signal sources in high-noise environments, connect the negative terminal of the signal source to the AI GND terminal on the SC-2345 screw-terminal block to reduce common-mode noise.
For information about how to configure the SCC-ACC01 module using NI-DAQmx, refer to the SCC Quick Start Guide.

Using the SCC-ACC01

Scaling Voltage Measurements

If you configured the SCC-ACC01 using Measurement & Automation Explorer (MAX) and are using NI-DAQ, the reading you get from the E Series DAQ device is properly scaled. Use scaling constants obtained from your sensor data sheet to convert the accelerometer voltage to the desired unit, such as newtons, m/s following steps to scale the readings:
1. Measure the accelerometer voltage.
a. Read the accelerometer channel on the E Series DAQ device
V
ESERIES
b. Calculate the accelerometer voltage using this formula:
SCC-ACC01
4
+
IEX (4 mA)
3 2
AC
Coupling
1

Figure 1. SCC-ACC01 Signal Connections

2
, or g. Otherwise, complete the
19 kHz
+
Lowpass
Filter
(CHX).
E Series
AI (
X
)
V
ACC
= V
ESERIES
/2
where
V
is the SCC-ACC01 input voltage.
ACC
V
© National Instruments Corporation 5 SCC-ACC01 Accelerometer Input Module User Guide
is the E Series DAQ device input voltage.
ESERIES
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Note Step 1 provides proper scaling for the amplifier in the SCC-ACC01 if the module is
not configured using MAX.

Specifications

Analog Input

2. If the module is configured using MAX, use scaling constants obtained from your sensor data sheet to convert V such as newtons, m/s
2
, or g.
voltage to the desired unit,
ACC
These ratings are typical at 25 °C unless otherwise stated.
Number of input channels.......................1 DIFF
Input range ..............................................±5 V (fixed gain of 2)
Input coupling.........................................AC (highpass 1-pole RC filter)
–3 dB cutoff frequency....................0.8 Hz
Filter type................................................Lowpass 3-pole Bessel
–3 dB cutoff frequency....................19 kHz
Passband flatness ....................................±0.3 dB, 10 Hz–5 kHz;
±1 dB, 5 Hz–10 kHz
Input impedance .....................................0.39 µF in series with 5 M
(powered on or off)
System noise ...........................................130 µV
(referred to input, [RTI])
1
This specification is calculated relative to the input range of the module.
SCC-ACC01 Accelerometer Input Module User Guide 6 ni.com
rms
1
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Transfer Characteristics

Gain........................................................ 2
Gain transfer
20
0
–20
Gain (dB)
–40
–60
–80
–100
0.01 0.1 1 10 100 1.1031.1041.1051.10
Frequency (Hz)
6
© National Instruments Corporation 7 SCC-ACC01 Accelerometer Input Module User Guide
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100
0
Phase transfer
Phase
(degrees)
–100
–200
–300
0.01 0.1 1 10 100 1.1031.1041.1051.10
Frequency (Hz)
Gain error................................................±1% of reading
Gain-error temperature coefficient .........±10 ppm/°C
Offset error .............................................±3mV RTI
Offset-error temperature coefficient.......±1.6 µV/°C
Nonlinearity ............................................10 ppm of full scale
Recommended warm-up time.................5 min
6

Amplifier Characteristics

Common-mode rejection ratio................80 dB at 60 Hz
Output range ...........................................±10 V

Excitation

Number of channels................................1
Constant-current source..........................4 mA
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Power Requirement

Physical

Maximum voltage level
without losing regulation .......................24 V
Temperature drift ................................... ±127 ppm/°C
Analog power......................................... 89 mW max
+15 V ..............................................3 mA max
–15 V............................................... 3 mA max
Digital power.......................................... 420 mW max
+5 V ................................................ 84 mA max
Dimensions............................................. 8.89 cm × 2.92 cm × 1.85 cm
(3.50 in. × 1.15 in. × 0.73 in.)
Mass ....................................................... 28.6 g (1.0 oz)
I/O connectors ........................................ One 20-pin right-angle
male connector, one 6-pin screw terminal
Field-wiring diameter............................. 28 to 16 AWG

Maximum Working Voltage

Maximum working voltage refers to the signal voltage plus the common-mode voltage.
Channel-to-earth (inputs) ....................... 42 VDC, 30 V
Channel-to-channel (inputs)................... 42 VDC, 30 V

Environmental

Operating temperature............................ 0 to 50 °C
Storage temperature ............................... –20 to 70 °C
Relative humidity................................... 10 to 90%, noncondensing
,
rms
Installation Category I
,
rms
Installation Category I
© National Instruments Corporation 9 SCC-ACC01 Accelerometer Input Module User Guide
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Maximum altitude...................................2,000 m
Pollution Degree (indoor use only) ........2

Safety

This product is designed to meet the requirements of the following standards of safety for electrical equipment for measurement, control, and laboratory use:
IEC 61010-1, EN 61010-1
UL 3111-1, UL 6101B-1
CAN/CSA C22.2 No. 1010.1
Note For UL and other safety certifications, refer to the product label or visit
ni.com/hardref.nsf, search by model number or product line, and click the
appropriate link in the Certification column.

Electromagnetic Compatibility

Emissions................................................EN 55011 Class A at 10 m
Immunity ................................................EN 61326:1997 + A2:2001,
FCC Part 15A above 1 GHz
Table 1
CE, C-Tick, and FCC Part 15 (Class A) Compliant
Note For EMC compliance, operate this device with shielded cabling.

CE Compliance

This product meets the essential requirements of applicable European directives, as amended for CE marking, as follows:
Low-Voltage Directive (safety)..............73/23/EEC
Electromagnetic Compatibility
Directive (EMC) .....................................89/336/EEC
Note Refer to the Declaration of Conformity (DoC) for this product for any additional
regulatory compliance information. To obtain the DoC for this product, visit
ni.com/hardref.nsf, search by model number or product line, and click the
appropriate link in the Certification column.
SCC-ACC01 Accelerometer Input Module User Guide 10 ni.com
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SCC-ACC01 Module Pin Assignments

Figure 2 shows the I/O connector pins on the bottom of the module.
4
5
1Pin 1 2Pin 2 3PWB Key 4 Pin 19 5Pin 20

Figure 2. SCC Module Bottom View

Table 1 lists the signal corresponding to each pin. AI (X) is an analog input signal channel of the E Series DAQ device. AI GND is the analog input ground signal and is the reference for AI (X). A GND is the reference for the ±15 V supplies and REF 5 V. AI GND and A GND connect to the SC-2345 at the SCC-PWR connector. GND is the reference for the +5 V supply.
1
2
3

Table 1. SCC-ACC01 Module Pin Assignments

Pin Number Signal
1 E Series AI (X)
2 E Series AI GND
3
4
5
6 E Series AI GND
7
8 E Series AI GND
9 +5 V
10 GND
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Table 1. SCC-ACC01 Module Pin Assignments (Continued)
Pin Number Signal
11 A GND
12
13 +15 V
14 –15 V
15
16
17
18
19
20
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