4-20mA signals

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Anonymous Poster	4-20mA signals 10/28/2009 10:55 PM
	how do I wire two 4-20 mA signals to one input?
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#2 Re: 4-20mA signals 10/29/2009 4:00 AM
	It can't be done. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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JRaef Guru Join Date: Sep 2006 Location: California, USA, where the Godless live next door to God. Posts: 4665 Good Answers: 804	#3 Re: 4-20mA signals 10/29/2009 3:15 PM
	If you can tolerate a delay in sampling your signals, you can buy what is called a "multiplexer" often abbreviated as "Mux". A Mux unit will take the two separate signals and switch them back and forth to your single input in a deterministic fashion. So you would need to accommodate that in your control device and have it only look at the proper signal when it comes in. this is done all the time on systems where response time is not critical. http://en.wikipedia.org/wiki/Multiplexer __________________ All I every really wanted to be, was... A LUMBERJACK!.
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_Leon_ Commentator Join Date: Jul 2009 Posts: 63	#4 Re: 4-20mA signals 10/29/2009 3:26 PM
	It depends what you are measuring,and what effect you require.If you`re looking for a digital signal at a pre-determined level of the measured value for example,it may be possible however,if you`re after a modulating output relative to 2 x modulating inputs,as the previous replies state,it cannot be done. More info required with regard to the control philosophy and what`s being measured etc etc
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porky2009 Commentator Join Date: Sep 2009 Posts: 72	#5 Re: 4-20mA signals 12/09/2009 4:57 AM
	why would you want to do that ??
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