Ten Analog inputs (4-20 mA) transmitted wireless

[dsasorin]

Hello. I'm Sorin, from Romania. I am engineer at Icemenerg, Bucharest.
I need to aquire 10 analog current signals 4-20 mA. (temperatures,levels, etc in

situated in opened field). These signals are faraway from my computer (300 m), so i

must do it wireless somehow. My thought was to use a single device (Converter) with

at least 10 analog inputs (4-20mA), and a numeric output. Then the numeric signal to

be sent wireless to 300m, to my computer, where there is a receiver with eventually

one USB output port.
Then Labview 8.5 will do the rest.... Can you tell me, if you have such a device

/system ? The Converter is the key.
I made a schematic in attachement.

[RavensFan]

NI makes wireless products.  Look at the NI.com homepage and search from there.

Here is a link to a page that is only two clicks away.  http://sine.ni.com/nifn/cds/view/main/p/sn/n24:Wireless/lang/en/nid/1036/ap/daq

[AnalogKid2DigitalMan]

Sorin:

NI recently released the WLS series, but they are voltage input only. You could convert the 4-20mA signals to a voltage by using a precsion resisitor. Do not know the transmitting range of the WLS series, also do not know how fast you need to sample. Another thing you may need to consider is full channel-to-channel isolation to minimize any ground loop issues.

http://sine.ni.com/nifn/cds/view/main/p/sn/n1:7850,n24:Wireless/sb/%2Bnigenso7/lang/en/nid/1036/ap/d...

There are many 4-20mA wireless transmitters (some with ranges of many km). Not sure what your budget is.

http://www.google.com/search?hl=en&source=hp&q=4-20ma+wireless+transmitter&aq=2&oq=%224-20mA%22+%2B+...

Hope this gets you started!

-AK2DM

Edit: I see Ravens Fan beat me to the first part while I was Googling around 🙂

Message Edited by AnalogKid2DigitalMan on 09-11-2009 02:51 PM

[AnalogKid2DigitalMan]

Sorin:

On second thought, 4-20mA signals should easily work with a 300m run of direct wiring, is that a viable option?

-AK2DM

[dsasorin]

Thank you all, for your answers.

Finally, I decided to do it wireless

Shortly, i have to aquire 4 temps and 6 currents (4-20mA) in the same time, at 1 S/s. The computer is 250 m away.

Which protocol is simplier to implement and to work to, ethernet (TCP/IP) or serial (rs-232) ?  Since now, i worked with serial.

I want that the programm .vi to be seen on many computers in a LAN. That's why i was thinking that TCP/IP is the best suited for my system.

So, what do you recomand ?

Thank's.

[ManLongAtNI]

Hello Sorin,

If you're looking to perform a wireless acquisition, I recommend looking into our wireless DAQ devices as stated above. What software will you be using to communicate with the hardware.

Regards,

Glenn

[dsasorin]

I use Labview 8.5 professional edition. 

I don't think wireless DAQ is best for my case.

DAQ module has only voltage inputs (or currents with additional precision resistors). I have to record temperatures and currents.

Also, the programm must run on a computer (server) and to be seen in LAN, JUST see, not control. So i need one simple system for aquisition.

I think i 'll use some transmitters with temperatures and currents inputs. And for the output i think is best tcp/ip protocol. My thought was that NI has such transmitters, althought i can find other brands here in Romania, with very good products.

I  made a schematic with my idea, in attachment.

And the big question was: is it tcp/ip protocol easier to implement (to programm) than serial RS-232, RS-485 ? 

Thanks. 

[dsasorin]

here is the schematic

[AnalogKid2DigitalMan]

Maybe using a Compact FieldPoint unit (ie cFP-1804) outfitted with some AI-110 modules. Note that the modules do not have a fast sampling rate. This could be connected to a wireless LAN link and your LabVIEW program running on a remote PC could poll the data via the LAN connection.

-AK2DM