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Active vs. Passive Signal
Exact difference between active and passive signal
1 out of 1 members thought this post was helpful...

Hi,

This may be a no brainer, but I'm new and learning. Could somebody please explain any differences between an active and passive signal?
Thank you in advance

Each word has multiple uses and meanings, depending circumstances in which they are used.

You'll have to be far more specific in a technical forum, to merit a useful response.

I specifically mean the signals out of temperature and/or pressure transmitters.

>Each word has multiple uses and meanings, depending
>circumstances in which they are used.
>
>You'll have to be far more specific in a technical forum, to
>merit a useful response.

now we are back to context in which the words are used.

most transmitters are considered active because of the electronic processing, while the signal produced may not be active in its behavior, but not all transmitters are electronic...

The usage depends on the situation you are in, and has a category of answers...

Generally, a device that is self-powered is an active device, and one that is externally powered is passive. See the following site:

http://blog.wika.com/general/active-passive-sensor/

The chart is a .jpg and can be converted to a .pdf for reference.

1 out of 1 members thought this post was helpful...

I believe Active / Passive is a poor choice of words.

Would you say a thermocouple is an active or passive
a pressure switch?

Or do they really mean a 4 wire transmitter as opposed to a two wire transmitter? (sorry I've only been doing this for 50 years)

Yes I believe they refer to 2-wire systems as passive and 3- and 4-wire systems as active.