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PRECISION 28000
Signal Conditioning
System






 
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28316B 16-Channel Long Distance
TEDS/IEPE Accelerometer Conditioner
General Purpose Vibration Measurements

The 28316B 16-Channel Long Distance TEDS/IEPE
Accelerometer Conditioner provides signal conditioning for either TEDS
equipped or traditional IEPE sensors. Ideal for modal and structural analysis
applications, the 28316B card is equipped with Precision Filters’ long-distance
TEDS (LDTEDS) technology that extends communication with TEDS equipped sensors
to 1500 feet. The card supports programmable filtering, gain and IEPE current.
In addition, sensor open, short and bias level are monitored and reported.
The 28316B provides a mixed mode transducer interface in
conformance with IEEE 1451.4 Smart Transducer Interface.
The mixed mode interface supports IEPE (Integrated Electronic
Piezo-Electric) sensors powered by current source and TEDS (Transducer
Electronic Data Sheet) capable sensors. TEDS information such as manufacturer
name, serial number, calibration data, etc. are readable by the system for use
in system scaling, identification, bookkeeping, troubleshooting and other
functions.
For IEPE sensors or remote charge preamps, a programmable
current source with 26 V compliance is provided.
TEDS sensors may be effectively applied to test models;
however, there is a restriction that the cable run between the signal
conditioner and the sensor be limited to 400 feet in order to be able to
properly read the TEDS. For applications such as weapons test or vibration test
on large structures, safety, environment, test article size and other factors
often require cable runs in excess of 1000 feet that have until now precluded
the use of TEDS equipped sensors.
The 28316B is equipped with Precision Filters' proprietary
Long Distance TEDS (LDTEDS) hardware. LDTEDS can communicate with
sensors at distances out to 1500 feet. The proprietary LDTEDS circuitry uses an
analog to digital converter to digitize the TEDS waveforms and utilizes a
digital signal processor to process the TEDS data.
The 28316B provides a selection of 4-pole filter
characteristics with
–5% corner frequencies. Filter bypass allows amplified wide-band
representation of input signals. Test inputs (voltage and current), along with
output monitor, make the system ready to work with the 28000 test subsystem
hardware to support Go/No-Go tests and Factory Acceptance tests. The Output Bank
Switch option allows the 28316B to work with data acquisition systems with a
smaller number of channels.
28316B Features
- 16 channels per card; 256 channels per chassis
- Precision Filters LDTEDS (Long-Distance Transducer Electronic Datasheet)
compliant
- Gain x0.5 to x128 with 0.05% resolution
- Auto-ranging gain for best ADC dynamic range
- Programmable 4-pole filters: BE4, BU4, EL4 and TD4
- Programmable corner frequency settings
- Current settings of 0, 1, 2, 4 or 8 mA (programmable, selected per
card)
- Sensor fault detector, open and short
- Sensor bias detector, in-range or out-of-range
- AC test current checks sensor, cable and signal conditioner health
- Overload detection
- Output monitor, selects any one of 256 outputs
- Test input for each channel
- Bank switch options switches the 256 output in banks of 16, 32, 64 or
128 channels to mate with various size data acquisition systems
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Bank Switch
The Output Bank Switch option allows the 28316B to work with
data acquisition systems with a smaller number of channels. Ideally, the
256-channel signal conditioning system would be mated with a 256-channel data
acquisition system. However, the user may have a smaller DAS with 16, 32, 64 or
128 channels. The Bank Switch, Option B, provides a means of mating to a lower
channel DAS:
- 16 banks of 16 channels for a 16-channel DAS
- 8 banks of 32 channels for a 32-channel DAS
- 4 banks of 64 channels for a 64-channel DAS
- 2 banks of 128 channels for a 128-channel DAS
The bank switch
can be set manually for sixteen, eight, four or two banks. The bank switch
outputs are buffered and brought out through the front panel 37-pin connector.
Sensor and Cable Health
Test inputs (voltage and current), along with output monitor
and test circuits on the 28000C-BIF1-FT Backplane Interface Card, make the system ready to work with
the 28000 Test System hardware to support Go/No-Go tests and Factory
Acceptance tests.
Traditional Go/No-Go tests for an IEPE sensor allow insertion
of a test signal to check the signal conditioning channel. It is also standard
to provide open and short detection on the sensor cables.
The 28316B provides two additional tests to verify sensor
health. The operating bias point of an IEPE sensor may change before failing, so
measuring the bias point is a means of monitoring the sensor health. The 28316B
provides a bias point detector with user specified limits. The second check is a
measure of the output impedance of the sensor buffer, which may shift suddenly
with a damaged sensor. A small AC current is superimposed on the DC IEPE supply.
The small AC voltage developed across the sensor’s output stage can be used to
infer the device’s output impedance. In addition, the small output voltage can
be used to provide an end-to-end check of the sensor, cable and signal
conditioning system.

Click to enlarge
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Auto Gain Ranging Mode
The auto gain ranging mode provides a means of setting up all
256 channels in three gain ranging periods, where the gain ranging period, T, is
selected from 1/8 S to 128 S depending on the signal type (periodic or random)
and the response of the structure (narrow-band or wide-band). When the
auto-ranging is initiated, all channels are set to a gain of x8 and the output
overload detector determines if the channel output exceeded the overload level
at any time during the period. If the overload was exceeded the gain is set to
x2 and if not the gain is set to x32. The overload detectors are reset and the
overload detectors operate for another period (2nd period). At the end of three
periods (3T) all 256 channels have been set to the operating gain. The output overload detector is set to allow for
crest factor and creep.
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TEDS Support
TEDS (Transducer Electronic Data Sheet) reader/writer option
is available as Option T on the 28316B card. Option T provides the ability to
read stored data on TEDS-compliant devices. Precision
Filters' proprietary
Long Distance TEDS (LDTEDS) support
provides the capability to communicate TEDS information across signal lines up
to 1500 feet long.
The separate TEDS reader/writer program 28000-TEDS-READER is
required to support Option T. The reader/writer program is compatible with IEEE
1451.4 V0.9 transducers.
TEDS data is displayed as a spreadsheet that can be displayed
and saved as a configuration file. 28316B system information such as channel
number and a time stamp of the time that TEDS information for each channel was
last read are provided.
Manufacturer’s information read from the sensor including manufacturer name, model number, version number and version letter of the sensor
together with sensor serial number and cal date are displayed in the table.
Accelerometer Template Information in accordance with the IEEE standard is
displayed as well as application dependent information. Sensor Sensitivity is
used to set channel gains for EU scaling of 28316B outputs.

28316B Card Installed in 28016B-M3 Frame
Channel Block Diagram

Click to enlarge
Download the
Spec Sheet
from the Reference Library
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Product Information
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Applications Examples
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Vibration analysis testing
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Modal analysis
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Structural analysis
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IEPE accelerometer conditioner
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Condition charge accels w/remote charge converter (RCC)
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AC amplifier/filter
Reference
The following Specifications
are available in Precision Filters'
On-line Library
for downloading:
28104A Quad Bridge Conditioner Specifications
28208 Octal Thermocouple Conditioner
28302B Dual
Vibration Amplifier
27304 Quad Dual Mode Charge Amplifier
28314 Quad Dynamic Charge/IEPE Conditioner
with LDTEDS
28316B 16-Channel TEDS/IEPE Accelerometer
Conditioner
28454A Quad Conditioner Specifications
28524 Quad Frequency to Voltage Converter
Modules
28608B Octal Programmable Filter Amplifier
27708A Octal
AC/DC Amplifier
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