Signal Conditioning

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open thermocouple detection

I am using an SCXI 1120 module with a 1320 terminal block to take temperature readings from k-type TCs. When we disconnect a TC the reading for that channel goes to around 272 C, which is in our measurement range. How can I get that reading to go out of range when the TC is removed?
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Greetings,

The following KnowledgeBase explains the concept of open-thermocouple detection:

Open-Thermocouple Detection

Since the SCXI-1120/SCXI-1320 combination does not have open-thermocouple detection circuitry, you will need to provide it yourself by connecting pull-up resistors between the CH+ terminals and voltage references. Since the channels of the SCXI-1120 are isolated, it is important to realize that connecting multiple pull-up resistors to the same voltage reference will break this isolation.

Good luck with your application.

Spencer S.
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Spencer, thanks for your response.
What is the importance of knowing my channels are non-isolated? (I don't know much about signal conditioning)
Thanks for your help,
Dave
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Dave,

If your input signals do not have differing common mode voltages, this will not be a big deal. However, biasing multiple channels to a common source will break the 250 Vrms channel-to-channel, common mode isolation.

Spencer S.
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