Measurement-computing TempBook rev.3.0 Instrukcja Użytkownika Pobierz pdf (Strona 147)

TempBook User’s Manual daqCommand Reference (

Enhanced

API) 11-23

The temperature conversion functions take input data from one or more scans from the Daq*. They then

examine the CJC and thermocouple readings within that scan and, after optional averaging, convert them to

temperatures which are stored as output. For example, see the readings in the table.

The first 2 readings of each scan are

non-temperature voltage readings to

compensate for the CJC circuit and

the shorted channel 0. The third

reading is from the CJC, and the

remaining 3 readings are from 3 type

J thermocouples. If the auto-zero feature is disabled, the first 2 readings will be ignored. Otherwise, the

first 2 readings will be used to remove offset errors in the CJC and T/C reading. The CJC and T/C readings

are used to produce one temperature result for each T/C reading. Thus, the 24 original readings are reduced

to 12 temperatures.

The conversion process has 2 steps: setup and conversion. Setup describes the characteristics of the

temperature measurement, and Conversion changes the raw readings into temperatures. All of the functions

return error codes as defined in Daqx.h which also includes the function prototypes and the definitions of

the thermocouple-type codes.

To measure temperatures, the scan must be set up so the T/C measurements consecutively follow their

corresponding CJC measurement (the CJC measurement need not be the first element in the scan). If auto-

zeroing is enabled, the CJC measurement must be preceded by both a CJC zero measurement and a T/C

zero measurement.

All of the thermocouples converted with a single invocation of the conversion functions must be of the same

type: J, K, T, E, N28, N14, S, R, or B. To measure with more than one type of thermocouple, they must be

sorted by type within the scan, and each type must be preceded by the related CJC.

The scan is not restricted to

thermocouple measurements. The

scan may include other types of

signals such as voltage, current, or

digital input; but conversion of

these readings is up to you. The

temperature conversion functions

cannot handle them.

The temperature measurements

must be made with the correct

gain settings. The gain settings

for the different thermocouple

types depend on the channel type and the bipolar/unipolar setting of the Daq* as specified in the table.

Note: Unipolar operations are not recommended for thermocouple measurement unless the measured

temperatures will be greater than the Daq* temperature.

When measuring thermocouples using the gains above, the following temperature ranges apply.

Reading

Scan 0 1 2 3 4 5

1 V or CJC Zero V or J Zero CJC J1a J1b J1c

2 V or CJC Zero V or J Zero CJC J2a J2b J2c

3 V or CJC Zero V or J Zero CJC J3a J3b J3c

4 V or CJC Zero V or J Zero CJC J4a J4b J4c

Gain Codes

Type Unipolar Gain

Code

Unipolar

Gain

Bipolar Gain

Code

Bipolar

Gain

CJC

TbkUniCJC TgainX100 TbkBiCJC TgainX50

TbkUniTypeJ TgainX200 TbkBiTypeJ TgainX100

TbkUniTypeK TgainX200 TbkBiTypeK TgainX100

TbkUniTypeT TgainX200 TbkBiTypeT TgainX200

TbkUniTypeE TgainX100 TbkBiTypeE TgainX50

N28

TbkUniTypeN28 TgainX200 TbkBiTypeN28 TgainX100

N14

TbkUniTypeN14 TgainX200 TbkBiTypeN14 TgainX100

TbkUniTypeS TgainX200 TbkBiTypeS TgainX200

TbkUniTypeR TgainX200 TbkBiTypeR TgainX200

TbkUniTypeB TgainX200 TbkBiTypeB TgainX200

Thermocouple mV Outputs For Temperature Ranges Depending on Ambient Temperature

T/C

Type

Measured Temperature Range

@ 0°C ambient

Measured Temperature Range

@ 25°C ambient

Measured Temperature Range

@ 50°C ambient

Temperature °C 0°C Output (mV) Temperature°C 25°C Output (mV) Temperature°C 50°C Output (mV)

-200 to 760 -7.9 to 42.9 -200 to 760 -9.2 to 41.6 -200 to 760 -11.8 to 39.0

-200 to 1372 -5.9 to 54.9 -200 to 1372 -6.9 to 53.9 -200 to 1372 -8.9 to 52.9 (50.0

-200 to 400 -5.6 to 20.9 -200 to 400 -6.6 to 19.9 -200 to 400 -8.7 to 17.7

-270 to 1000 -9.8 to 76.4 -270 to 1000 -11.3 to 74.9 -270 to 1000 -14.5 to 71.7

N28

-270 to 400 -4.3 to 13.0 -270 to 400 -5.0 to 12.3 -270 to 400 -6.4 to 10.9

N14

0 to 1300 0.0 to 47.5 0 to 1300 -0.7 to 46.8 0 to 1300 -2.0 to 45.5

-50 to 1780 -0.2 to 18.8 -50 to 1780 -0.4 to 18.7 -50 to 1780 -0.7 to 18.4

-50 to 1780 -0.2 to 21.3 -50 to 1780 -0.4 to 21.1 -50 to 1780 -0.7 to 20.8

50 to 1780 0.0 to 13.4 50 to 1780 0.0 to 13.4 50 to 1780 0.0 to 13.4

1 2 ... 142 143 144 145 146 147 148 149 150 151 152 ... 165 166

Komentarze do niniejszej Instrukcji

Brak uwag

Measurement-computing TempBook rev.3.0 Instrukcja Użytkownika Strona 147

Komentarze do niniejszej Instrukcji

Powiązane produkty i podręczniki dla Sprzęt komputerowy Measurement-computing TempBook rev.3.0