The SMTAS08 Temperature Acquisition System

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PRODUCT DESCRIPTION

The Smart Temperature Acquisition System (SMTAS08) is an 8 channel temperature measurement system. It was designed to get the best possible temperature measurement results with the SMT160-30 Smartec temperature sensors. This is a three-terminal integrated sensor with a duty-cycle-modulated square-wave output signal (see the Temperature Sensor page).

If the SMTAS08 board is equipped with the TO18 version of the SMT160 sensor, then an absolute accuracy of 0.7°C is obtained. The resolution however is 0.01°C ! If calibration is possible within your application, then an absolute accuracy of 0.02 °C to 0.05°C can be achieved.

The complete specification of the temperature sensor range is presented in the datasheet, which should be consulted in conjunction with the SMTAS08 manual. (You can download both at the SUPPORTSHOP)

FUNCTIONAL DESCRIPTION

The SMTAS08 is equipped with a Microchip PIC16F876 microcontroller. An RS232 interface chip offers external serial communication with the microcontroller. In turn each of the sensors is powered by a corresponding processor output. An analog multiplexer (74HC4051), which is controlled by the microcontroller, selects one of the eight sensor outputs by connecting it to the microcontroller input port. The input is then sampled to measure the dutycycle for this sensor (represented by two counter values, t1 and t2). This process is repeated for each of the sensors, after which the 8 values of t1 and t2 are sent to the RS232 port.

Because each of the sensors is only powered during its respective measuring cylce, the selfheating is negligible, increasing overall accuracy.

the SMTAS08 board in front of a Labview screen.

SOFTWARE

For controlling and reading the SMTAS08 board, a Labview program (see picture above) is available as well as a Visual Basic program (obsolete now). Both can be downloaded from the SUPPORTSHOP. The PIC processor program listing (ASM source code) can also be found there.

A Visual Basic example for the SMTAS08 board (obsolete now)
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A windows Temperature Logger program called LogSmart is now available, which creates an Excel format datafile. The program can be configured in a number of ways: Sampling and log Interval, Duration, Filtering etc. The same program can used with the SMTAS08 board, as well as with the two versions (serial and USB) of the SMTAS04 board.

SUPPORT

All relevant documentation and files (data sheet, application notes, software etc.) for our products can be downloaded from the SUPPORTSHOP page.

IPGEO

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