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Catalogue Product Guide 2007

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1. What is TEDS?

TEDS stands for Transducer Electronic Data Sheet. It contains information relevant to the sensor in question, such as serial number, calibration dates and calibration factors. TEDS is defined by the TDL or Template Description Language as defined by the IEEE 1451.4 standard.

2. What is TDL?

TDL stands for Transducer Description Language. Similar to a computer language TDL allows storage of TEDS parameters in the most space efficient manner. This data compression is needed due to the limited amount of storage space available in typical TEDS memory.

3. What is a TEDS template?

A TEDS template is defined by the TDL and IEEE1451.4 standard. The template is a set of fields that define data type, data size, and actual

information.

4. What is the purpose of TEDS?

TEDS will simplify the configuration of electronic equipment by providing

all the information needed for the setup and calibration of electronics.

Ideally the electronics would self configure.

5. How is TEDS implemented?

TEDS is implemented by using a 1-Wire EEPROM device. This device

receives and transmits bits of information that is permanently stored or changed as desired. The host instrument is responsible for the data transfer.

6. How is TEDS stored?

TEDS can be stored in any type of electronic memory. Typically the Maxim/Dallas 1-wire based memory is the preferred memory due to low pin out count and ease of integration into sensors. However data space

is limited.

7. How are TEDS created?

The IEEE 1451.4 standard provides predetermined templates for most sensors. However by using the TDL language new templates can be created. The TDL code would then be provided to end user. It then becomes their responsibility for translation.

8. What are the benefits of TEDS?

1. Calibration information can be stored in the sensor itself, losing certificates will not be a problem.

2. Sensor specific information can be updated at any time.

3. Auto-configuration of TEDS enabled industrial instrumentation would allow quick swapping of sensors as needed and save time.

4. Standard TEDS templates are available for virtually any type of sensor.

9. What are the limitations of TEDS?

1. Chip could be damaged due to mishandling or possible ESD discharge.

Data would be irrecoverable.

2. Chip could be accidentally written over, losing information.

3. Instrumentation may not support all templates or configurations.

4. Templates may not support all desired parameters.

5. Calibration discrepancies exist between instrumentation, even if the same type. Meaning that a specific sensor output may not match if

interfaced to different instruments. TEDS is designed as an information

carrier. Use in calibration or auto configuration may carry some accuracy

discrepancies.

10. Is the "TEDS" option available on FUTEK products?

Yes for all sensors and selected instruments such as the IPM500, IBT500 & also CSG series in-line amplifier.

11. Does FUTEK upgrade existing Customer sensors with-the "TEDS" option? Yes.

FUTEK TEDS Sensor Kit

Frequently Asked Questions About Instrumentation

1. What is the difference between analog and digital signals?

An analog signal is infinitely continuous, a digital signal is quantized or broken up depending on bit resolution.

2. What is a bit?

A bit of information represents either an "on" or "off" state.

3. What is a bit resolution?

Bit resolution is the number of steps or possibilities for a given # of bits. For example, a 4 bit number has 2 to the power of 4 possibilities which equals 16 distinct possibilities.

4. What are "nibbles", "bytes" and "words"?

A nibble = 4 bits, a byte = 8 bits, a word = 16 bits.

5. What does "kilo", "mega" and giga" mean in the digital

domain?

Kilo = 1024, mega = 1024², giga = 1024³. Therefore 8k bytes means that we have 8 x 1024 = 8192 pieces of 8 bit information.

6. What is analog to digital conversion?

This is the process in which an analog signal is quantized into a digital signal. Usually performed by a device known as an analog to digital converter.

7. What is frequency response?

Another term to describe bandwidth.

8. Why do I sometimes see a -3db cutoff frequency listed

as a specification? What does this mean?

This is the point where the signal will attenuate to about 70.7% of the

usually chosen as a marker in which to describe the

9. What is a industrial sampling rate?

The number of times per second an analog to digital industrial converter takes readings and converts per second.

10. What is the Nyquist criteria?

In order to re-create an analog signal, the sampling rate must be at least twice the frequency of the source analog signal.

11. What is bandwidth?

The span of input frequencies that a device is designed to operate within.

12. Why is the bandwidth sometimes lower than the sampling rate?

In order to capture small details of a real world signal, higher sampling

rates are needed to avoid the aliasing and meet the Nyquist criteria.

The sampling rate is your time domain resolution.

13. Is the sampling rate affected by electrical loads such as impedance of a sensor?

Typically no. However, in some multiplexed systems the sampling rate is

divided equally among different channels.

14. What is output and input impedance?

Output impedance is the minimum resistive load on an electrical output

that will not cause a voltage drop for a given voltage. Input impedance

is the amount of resistive loading in an electrical input. Instrumentation

typically has very high input impedance to reduce resistive errors.

15. How many sensors can be connected to instrumentation?

This is dependent on output impedance of excitation circuitry. The parallel combination of resistive loads cannot be less the minimum required

load on the given electrical output.