Measurement-computing USB-5203 Manuel d'utilisateur télécharger pdf (Page 25)

USB-5203 User's Guide Specifications

Thermistor measurement accuracy

The error shown in Table 7 below does not include errors of the sensor itself. The sensor linearization is

performed using a Steinhart-Hart linearization algorithm. These specs are for one year while operating the

device between 15 °C and 35 °C. The specification does not include lead resistance errors for 2-wire thermistor

connections. Please contact your sensor supplier for details on the actual sensor error limitations.

Total thermistor resistance on any given channel pair must not exceed 180 kΩ (refer to Table 8 below).

Table 7. Thermistor measurement accuracy specifications

Thermistor Temperature Range (°C) Maximum Accuracy Error (°C)

Ix+ = 10 µA

2252 Ω –40 to120 ±0.05

3000 Ω –40 to120 ±0.05

5000 Ω –35 to120 ±0.05

10000 Ω –25 to120 ±0.05

30000 Ω –10 to120 ±0.05

Typical resistance values at various temperatures for supported thermistors are shown in Table 8 below.

The device cannot measure resistance values greater than 180 kΩ in thermistor mode. The 180 kΩ resistance

limit includes the total resistance across the current excitation (Ix+/Ix–) pins, which is the sum of the thermistor

resistance and the lead resistances.

For accurate three-wire compensation, the individual lead resistances connected to the Ix+/Ix– pins must be of

equal value.

Table 8. Typical thermistor resistance specifications

Temp

(°C)

2252 Ω

thermistor

3000 Ω thermistor 5 kΩ thermistor 10 kΩ thermistor 30 kΩ thermistor

–40 76 kΩ 101 kΩ 168 kΩ 240 kΩ 885 kΩ

–35 55 kΩ 73 kΩ 121 kΩ 179 kΩ 649 kΩ

–30 40 kΩ 53 kΩ 88 kΩ 135 kΩ 481 kΩ

–25 29 kΩ 39 kΩ 65 kΩ 103 kΩ 360 kΩ

–20 22 kΩ 29 kΩ 49 kΩ 79 kΩ 271 kΩ

–15 16 kΩ 22 kΩ 36 kΩ 61 kΩ 206 kΩ

–10 12 kΩ 17 kΩ 28 kΩ 48 kΩ 158 kΩ

–5 9.5 kΩ 13 kΩ 21 kΩ 37 kΩ 122 kΩ

0 7.4 kΩ 9.8 kΩ 16 kΩ 29 kΩ 95 kΩ

Throughput rate to PC

The analog inputs are configured to run continuously. Each channel is sampled twice per second. The maximum

latency between when a sample is acquired and the temperature data is provided by the USB unit is

approximately 0.5 seconds.

Maximum throughput to a CompactFlash® memory card is 1 S/s per channel.

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Measurement-computing USB-5203 Manuel d'utilisateur Page 25