Functioning IP/IE3312
Thermocouples can be classified as active measuring sensors. They exploit the thermo-electric effect (Seebeck, Peltier, Thomson). Where two electrical conductors of different materials (e.g. iron and constantan) make contact, charge is transferred across the contact surface. A contact potential develops, and is strongly dependent on temperature. The thermally generated voltage is both a function of the temperature being measured, T, and of the comparison temperature, Tv, at the point where contact is made with the thermocouple. Since the coefficients are determined at a comparison temperature of 0°C, it is necessary to compensate for the effect of the comparison temperature. This is done by converting the comparison temperature into a comparison voltage that depends on the type of thermocouple, and adding this to the measured thermal voltage. The temperature is found from the resulting voltage and the corresponding curve.
Temperatures are measured 1/10°C (1 Digit = 0,1°C). A missing cold compensation sensor (PT1000) or wire break is reported and indicated by the Error LED.
Format of the process data
|
process data (hex) |
process data decimal (integer) |
temperature value |
|---|---|---|
|
0xF63C |
-2500 |
-250°C |
|
0xF830 |
-2000 |
-200°C |
|
0xFC18 |
-1000 |
-100°C |
|
0xFFFF |
-1 |
-0,1°C |
|
0x0000 |
0 |
0,0°C |
|
0x0001 |
1 |
0,1°C |
|
0x03E8 |
1000 |
100°C |
|
0x07D0 |
2000 |
200°C |
|
0x1388 |
5000 |
500°C |
|
0x2134 |
8500 |
850°C |
Block diagram
Conceptual circuit diagram
