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AM16/32B Relay Analog Multiplexer

Two problems would arise due to the properties of thermocouple

wire:

An extraneous thermocouple voltage would be added to the non-

thermocouple signal at the junction of dissimilar metals (e.g. the

multiplexer COM terminals). The magnitude of this signal would

vary with the temperature difference between the datalogger and the

AM16/32B.

Some thermocouple wires have a greater resistance than copper,

which adds resistance to the non-thermocouple sensor circuit. For

example, constantan is approximately 26 times more resistive than

copper.

COM EVEN H

COM EVEN L

EVEN H

EVEN L

SENSOR SHIELD

COM

"4 X 16" Mode

COM ODD H

COM ODD L

ODD H

ODD L

21X/

CR7

CR10(X)

CR3000/

CR800/CR850/

CR23X/CR1000/

CR5000

H H H

L L L

H H H

L L L

FIGURE 18. Differential Thermocouple Measurement with Reference Junction

at the Datalogger

COM EVEN H

COM EVEN L

EVEN H

EVEN L

SENSOR SHIELD

COM

"4 X 16" Mode

COM ODD H

COM ODD L

107

ODD H

ODD L

CR23X/

CR800/

CR850/

CR1000

21X/

CR7

CR10(X)

CR3000/

CR5000

H H H H

L L L L

EX E E VX

H H H H

L L L L

FIGURE 19. Differential Thermocouple Measurement with Reference Junction

at the AM16/32B

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Campbell AVW1 Specifiche Pagina 38

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