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4.3 Thermocouple Inputs
The FlightDaq-TL can only measure thermocouples when used in conjunction
with the Chell Smart Lemo®. The Smart Lemo® forms the cold junction of the
thermocouple by crimping the thermocouple alloy to copper tubes. The
temperature of this junction is then measured by a 10kΩ thermistor which is
bonded to the copper tubes. There is an (optional) internal memory within the
Smart Lemo® which can carry the calibration of the thermocouple and/or the
thermistor.
For all thermocouple ranges, the primary input is set to ±78mV to measure the
hot junction and the secondary input is set to 5V which, when combined with the
excitation will measure the output of the thermistor.
The results from the two inputs are converted to temperature by using the
appropriate NIST look-up-tables for both the hot junction and the thermistor.
This is all configured automatically when the thermocouple input is selected.
Configuration
Number
Type
Code
Type
Variant
Range
Pri Range
Sub Range Excitation
17
11
Thermocouple
B
78mV
5V
10kΩ
18
12
Thermocouple
E
78mV
5V
10kΩ
19
13
Thermocouple
J
78mV
5V
10kΩ
20
14
Thermocouple
K
78mV
5V
10kΩ
21
15
Thermocouple
N
78mV
5V
10kΩ
22
16
Thermocouple
R
78mV
5V
10kΩ
23
17
Thermocouple
S
78mV
5V
10kΩ
24
18
Thermocouple
T
78mV
5V
10kΩ
Summary of Contents for FlightDaq-TL
Page 20: ...Page 19 5 2 The Setup tab Figure 5 21 Main Setup page...
Page 25: ...Page 24 Figure 5 52 Live Data Page Figure 5 53 Live Data Page...
Page 46: ...Page 45 Select an additional Scan List in this case we have chosen 4...
Page 47: ...Page 46 Then disable the secondary and tertiary data streams...