I want to log (4) 4-20ma signals to a PC inexpensively.

[jameshannon]

I have 4 4-20ma signals that I want to bring into a PC, graphically display in real time and historically log.  What is the cheapest way out of this?

[Joe_H]

I would get a USB-6000 series DAQ device and run the current through a 1% resistor of some value and record the voltage. I do not know os a cheaper way to do 4 at a time.

[Dennis_Knutson]

Joe just beat me to to it. The cheapest is the one at http://sine.ni.com/nips/cds/view/p/lang/en/nid/14604. It even includes datalogger software so you don't have to purchase anything else.

[Joe_H]

Thanks for the stars dennis.

Message Edited by Jhoskins on 03-28-2006 11:14 AM

[jameshannon]

This unit looks promising..thanks guys.

[Joe_H]

It is also extremely easy to use I have a couple of them . You can also check out easydaq and see what they have, they may me cheaper but I cannot vouch for there products because I have never used them.

[AnalogKid2DigitalMan]

Please be aware that it's input impedance is a lowly 144Kohm, not your typical 10-100Gohm on traditional DAQ cards. So take this into account when you select your sense resistor so your results match expected values.

[jameshannon]

I have this worked out to the point where I exceed the distance recommended for USB.  Is there any way to communicate wireless to the datalogger.  The datalogger will be on a rollaround test cart that will be in a 50 x 50' lab.  Any ideas?

[Joe_H]

So what you are saying is that the PC could be anywhere but you want the USB-6009 to be stationary at the sensors correct.

[unclebump]

Here are some devices that let you extend USB connections with a CAT5 cable.

http://www.blackbox.com/Catalog/Detail.aspx?cid=308,1431,1432&mid=4911

http://www.blackbox.com/Catalog/Detail.aspx?cid=308,1431,1432&mid=3340

http://www.bb-elec.com/product_family.asp?FamilyId=100&TrailType=Sub&Trail=33

And a device that lets you put USB drops on your ethernet.

http://www.bb-elec.com/product.asp?SKU=ANYWHEREUSB/5

Message Edited by unclebump on 03-28-2006 03:37 PM