National Instruments SCC-ACC01 User manual

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.

SCC-ACC01 Accelerometer Input Module User Guide 2 ni.com
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.

©National Instruments Corporation 3 SCC-ACC01 Accelerometer Input Module User Guide
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.

SCC-ACC01 Accelerometer Input Module User Guide 4 ni.com
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 ni.com/manuals.
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.
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 Signalssection.
For single-stage input conditioning, plug the SCC-ACC01 into any socket
J(X+1), where Xis 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 Xis 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 Xis 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.

©National Instruments Corporation 5 SCC-ACC01 Accelerometer Input Module User Guide
Figure 1. SCC-ACC01 Signal Connections
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/s2, or g. Otherwise, complete the
following steps to scale the readings:
1. Measure the accelerometer voltage.
a. Read the accelerometer channel on the E Series DAQ device
VESERIES (CHX).
b. Calculate the accelerometer voltage using this formula:
VACC = VESERIES /2
where
VACC is the SCC-ACC01 input voltage.
VESERIES is the E Series DAQ device input voltage.
IEX (4 mA)
E Series
AI (
X )
+
–
+
–
4
3
2
1
SCC-ACC01
ACC AC
Coupling
19 kHz
Lowpass
Filter

SCC-ACC01 Accelerometer Input Module User Guide 6 ni.com
2. If the module is configured using MAX, use scaling constants obtained
from your sensor data sheet to convert VACC voltage to the desired unit,
such as newtons, m/s2, or g.
Note Step 1 provides proper scaling for the amplifier in the SCC-ACC01 if the module is
not configured using MAX.
Specifications
These ratings are typical at 25 °C unless otherwise stated.
Analog Input
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 MΩ
(powered on or off)
System noise ...........................................130 µVrms
(referred to input, [RTI])1
1 This specification is calculated relative to the input range of the module.

©National Instruments Corporation 7 SCC-ACC01 Accelerometer Input Module User Guide
Transfer Characteristics
Gain........................................................ 2
Gain transfer
Gain (dB)
0.01 0.1 1 10 100 1.1031.1041.1051.106
–100
–80
–60
–40
–20
0
20
Frequency (Hz)

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Phase transfer
Gain error................................................±1% of reading
Gain-error temperature coefficient .........±10 ppm/°C
Offset error .............................................±3mVRTI
Offset-error temperature coefficient .......±1.6 µV/°C
Nonlinearity ............................................10 ppm of full scale
Recommended warm-up time.................5 min
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
Phase
(degrees)
Frequency (Hz)
0.01 0.1 1 10 100 1.1031.1041.1051.106
0
–300
–200
–100
100

©National Instruments Corporation 9 SCC-ACC01 Accelerometer Input Module User Guide
Maximum voltage level
without losing regulation ....................... 24 V
Temperature drift ................................... ±127 ppm/°C
Power Requirement
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
Physical
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 Vrms,
Installation Category I
Channel-to-channel (inputs)................... 42 VDC, 30 Vrms,
Installation Category I
Environmental
Operating temperature............................ 0 to 50 °C
Storage temperature ............................... –20 to 70 °C
Relative humidity................................... 10 to 90%, noncondensing

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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
FCC Part 15A above 1 GHz
Immunity ................................................EN 61326:1997 + A2:2001,
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.