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SMARTEC PRODUCTS FAQ LIST
SMartec Temperature Acquisition System 08 (SMTAS08)
Which model of the SMT160-30 temperature sensor should I use in combination with the
SMTAS08 temperature acquisition system?
The sampling rate of 5 Mhz at which each temperature sensor connected to the SMTAS08 board
is sampled, results in a resolution of 0,015°C. The absolute accuracy, however depends on
the absolute accuracy of the connected sensor. Because the TO18 model has a guaranteed
accuracy of better than 0,7°C, this sensor model is recommended for use together with the
What type of wires do I need to connect a SMT160-30 sensor to a SMTAS08 board and how long
can they be?
You can use any unshielded wire you like. Very often plain telephone wire or unshielded
ethernet cable is the easiest solution. The wires may be up to 20 meters long, without a
noticable loss in accuracy. Beyond that length, the block shaped signal will start to
deteriorate, therefor diminishing the accuracy. If you need a longer distance and you are
willing to accept a certain loss in accuracy, you can do it. The quality of the signal can
be judged by connecting an oscilloscope.
SMTIR990x Infrared sensor
What is the spectral effect of the glass window which comes standard with the Smartec infrared sensors SMTIR9901 and SMTIR9902?
These sensors have a optical window with a high pass filter characteristic. The cut-off wavelength is 5,5 micrometer. This make the IR sensor especially suited for applications in the range of room temperature up till a few hundred degrees Celsius. On request these sensors can be fitted with other filter types (high quantities only).
What happens if I put another filter in front of the SMTIR990x infrared sensor?
The characteristic of the second filter will have to be "multiplied" by the 5,5 micrometer high pass filter of the sensor itself, in order to obtain the overall filter behaviour. So if you add another filter with, let's say, a low pass filter of 4 micrometer, no IR radiation will be able to get to the thermopile elements inside.
Universal Transducer Interface
Can I connect a Smartec Temperature Sensor like the SMT160-30 to the UTI?
No. The STM160-30 has a digital output and the UTI has been specially designed to connect all kinds of analogue sensors (like small capacitors, PT100 and PT1000 elements, resistive bridges etc) directly to a microcontroller.
My UTI evaluation board is not working with a terminal program and also not with the
Labview program. What is wrong?
Make sure that the power is connected properly and that you have applied the correct
voltage (7 to 15 volt DC). If the green led (D1) is lit, you must be able to get the board running. Make sure that the serial cable is a straight one (no cross cable) and that the settings for the serial port are ok. The new board has automatic baud rate detection built in the PIC processor. This is why the @ command is needed as the first command before the other commands can be used. The old board runs at a speed of 19200 bits per second.
My UTI evaluation board is working fine with a terminal program but not with the Labview program. What is wrong?
If you can control the board from a terminal program it means that the board is working fine. The Labview program EVAL-UTI.EXE can only work properly if it is in the same directory as the serial portdriver SERPDRV (no filename extension!). This is true for both the old version of the board and for the new version.
If you have an old version of the board (it says: "Rev.1 1998" on the side of the printed circuit board), then you must use the version of the software that was delivered together with the board on floppy disk. If you have the more recent version of the board ( it says: "v. 2.0 SMARTEC B.V. - 2001") then you must use the version of the software that can be downloaded at the SUPPORTSHOP.
If you have lost the software for the old board, please send us an email, so we can send it to you.
You can easily check the version of the software on your computer with the following
EVAL-UTI.EXE date 03/06/98
SERPDRIVE date 06/04/97
EVAL-UTI.EXE date 18/09/01
SERPDRIVE date 15/01/02
When I am running the UTIkit with a terminal program, I can see the Hexadecimal data
coming in, but what does it exactly mean?
The terminal program will show you the raw data from the UTI. Depending on which of the 16 different modes of the UTI you are using, the ouput signal of the UTI consists of 3, 4 or 5 phases. The actual information about the value of your component to be measured is coded in the duration of these phases. The PIC processor measures each of these phases with a counter / timer function and sends it to the serial port in HEX format. So you will see 3,4 or 5 HEX values per line. These values (actually the number of processor timer tics) have to be substracted an divided according the the formulas that you can find in the data sheets, in order to calculate the unknown value of your component. This so called 3 variable method fully compensates for the offset and gain errors in the UTI and also eliminates the need to exactly know the clock speed of the PIC processor. Therefor the UTI is said to be a self-calibrating interface.
If you want to know more about this, please read:
APPUTI06.PDF Startup guide for measurement of capacitors with three signal technique, January 2003
Or, for the French: APPUTI12FR.PDF : Mesurer précisément des petits
signaux issus de capteurs distants avec un microcontrôleur, janvier 2003
What is the internal frequency of the UTI?
There is no such thing as THE internal frequency of the UTI, because the internal
oscillator is modulated by the components to be measured. The internal frequency will be different for each phase and depends on the value of the components connected to the UTI.
The free running frequency (Offset phase), however, is about 50kHz. If you want to check the frequencies, you can have a look with an oscilloscope and you will know everything (it will also help you better understand theUTI).
Can I measure the output signal of the SMTIR990x Infrared signal with a UTI evaluation kit?
The UTI evaluation board supports the 16 different UTI modes, but is not made to measure very small DC voltages, like the voltage from the IR sensor.
Can I measure the output signal of the SMTIR990x Infrared signal with a UTI circuit?
Application note APPUTI10.pdf describes an application where thermocouple output is measured with a UTI. Basically this is a DC voltage measurement. The thermocouple output voltage range = +/- 200mV. In principle the same setup could be used to measure the infrared sensor output, but the sensitivity would be largely insufficient. For many applications of the IR sensor the DC output is likely to be in the MICROVOLT range.
TIP TIP TIP TIP:
When developing applications for the UTI or performing measurements (especially capacitive ones) , it is highly recommended to have a look at the output signal (pin "OUT") with an oscilloscope. Because the UTI output signal is a signal that consists of different phases, each with it's own timing, normally it would be very difficult to make your oscilloscope trigger at the right moment, to give you a good image of the output signal. In order to facilitate the triggering and synchronisation, the UTI evaluation board is supplied with a pin called "SNC". If you connect this pin to the external synch input of your scope, then you should have no problems with the triggering. (Don't forget to put the Scope in external trigger mode!)
All relevant documentation and files (data sheet, application notes, software
etc.) for our products can be downloaded from the SUPPORTSHOP page.