4-20mA current loops

[Steve]

We have developed some new E-block designs for 4-20mA current loops, but we're we're not entirely happy with the features they provide. Before we commit to manufacture we are conducting some additional market research.

If you use this technology or hope to in the future, can you please contact me because I would like to hear your opinions on what we have and what you want.

Thanks!
Steve.

[JohnCrow]

Hi Steve
is your new e-block idea for simulate , measure or both.

Think one of commonest models we see at work is the Druck UPS-ii type.
These have the normal 4/8/12/16/20mA step on simulate and measure input loop

Other common format is % scale where 0% = 4mA 25%=8mA etc to 100% = 20mA

Will this have the normal 24 V drive.

The Druck is a small compact unit and not suitable for automated control which is what I guess you e-block would be aimed at.
I would have though it would be a lot more specialised, possibly limit market than say something like CAN or LIN buses , as 4-20mA is not something well known outside of instrument and control engineering. So i supppose you do need to test the market first.

Microcontrollers for me are a hobbiest interest, so although I would have interest in experimenting with one at home, that would depend on cost.
But its great to see the way you have expanded the range of products even over the last 3 or so years I have been using them.

[Steve001]

Hello Steve,

We use 4 - 20 & 0 - 20Ma loops at work, mainly 4 - 20 for the transmitters and we set up the receiver end for 0 - 20 Ma, this been so, that we can generate an error if 4ma is not seen (ie) a broken loop .

I made an eblock last year using a XTR110 & a DAC1220N Chips Both from RS and am very happy with it , no noticiable drifting and very stable

this chip can be set up for 0 - 20 Ma and 4 - 20 very easily and works from a 15v supply.

http://uk.rs-online.com/web/p/amplifiers-misc/0647621/


Steve

[Steve001]

Just looked and the Dac1220n is now obsolete . . sorry for that

Sujested replacement .

http://uk.farnell.com/national-semicond ... dp/9486640
http://uk.rs-online.com/web/c/?sra=oss& ... rm=dac0800

steve

[Steve]

Thanks for the feedback, Steve.

Our current design is centred on the XTR117 which is a lot cheaper than the XTR110 but is SMD-only (which makes things a bit more expensive overall for low-quantity production). We're going to look again at the other chips in the XTR range to see if there is a better alternative.

[Lord Grezington]

Hi

I know this is an old thread, but I have just come up with a very similar project. I was just hoping to use a 250 Ohm resister between the Analogue Input and ground and go from 1-5Vdc. I will use a bit of signal conditioning as well in the program.

Does anyone see a potential issue with this?

Graham

[Steve001]

No that works quite well we somtimes do it at work

here is the resistor we use too

rs part number 217-3201

steve

[Lord Grezington]

Thanks Steve

Grez