# Recommend me a datalogging/ pc connectable DMM



## Raymond (Apr 2, 2008)

I'm searching for a DMM, which I can connect to my pc to store measurement. If the DMM has it's own memory, that would be nice too. 

I'm looking for a reasonably accurate, reliable DMM. Most of my measurements are simply voltage/current/resistance, but a relative mode and a true RMS measurement would be nice too.

I've discovered that Uni-trend has some nice models, which are also affordable. Any experience with that brand?

I'm currently looking at these three models. The 7x models cost about the same, and the UT60E model costs half that.

http://www.uni-trend.com/UT60E.html
http://www.uni-trend.com/UT70D.html
http://www.uni-trend.com/UT71D.html

The UT60E does what I want, and is cheap.
The UT70D does not have a memory, but is fast, accurate and has a 79999 count display.
The UT71D is USB, has a memory for 10K measurements and is also accurate. Not as fast or a 79999 count display like the 70D.

What are your recommendations?


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## matrixshaman (Apr 2, 2008)

I haven't looked much at these except to say there's a couple cheap Chinese ones on eBay. What does that UT60E sell for (in US $ ) ?


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## Raymond (Apr 3, 2008)

They're sold here under the voltcraft brand by conrad electronics. They cost about the same amount of euro as dollars on ebay.


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## rantanplan (Apr 3, 2008)

I own a Voltcraft VC840, which looks identically to the UT60E, for a couple of years now. I´m not an electonics expert and therefore use it only for simple tasks too, but I´m quite happy with it. It´s very reliable and tough too, imho.

Its interface is electrically isolated from the computer through some kind of optocoupler-interface, but for use with a modern computer, you´ll need a RS232 to USB adaptor ... but the cheap chinese ones worked for me so far .

I also have a Voltcraft VC940, which is more accurate and has the capability of doing power measurements on AC line. But apart from that, it has its flaws ... buggy "software", cheap build quality ... and it´s nearly twice as expensive as the VC840 .


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## PEU (Apr 3, 2008)

Raymond said:


> I'm searching for a DMM, which I can connect to my pc to store measurement. If the DMM has it's own memory, that would be nice too.
> 
> I'm looking for a reasonably accurate, reliable DMM. Most of my measurements are simply voltage/current/resistance, but a relative mode and a true RMS measurement would be nice too.
> 
> ...



I have the UT60E for home use and the UT71B at the office, both are very nice units, of course the 71 is better, I use the ut60 serial interfase with an usb-rs-232 converter and it works OK. I never used the standalone datalogging capabilities of the 71B, I used it always hooked to a PC.

The UT60E is one of the cheapest RMS multimeters 

From your post, I think both units cover your needs. 


Pablo


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## Handlobraesing (Apr 3, 2008)

Here's my personal opinion.

Having an interface is one thing.
Having a good software to do the logging is another. You'd have to know the meter's communication protocol before you can even write your own.


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## Raymond (Apr 3, 2008)

Handlobraesing said:


> Here's my personal opinion.
> 
> Having an interface is one thing.
> Having a good software to do the logging is another. You'd have to know the meter's communication protocol before you can even write your own.



I have no interest to write my own software. The communication protocol for these DMM's is open, and can be found on the manufacturers website. The conrad website has even more info on the protocol. There are different programs out there that work with these DMM's. But my interest is mainly graph the values. So, as long as the software is capable of exporting the measured data to a format that Excel can understand, I'm happy 



PEU said:


> I have the UT60E for home use and the UT71B at the office, both are very nice units, of course the 71 is better



How do you consider the UT71B better?



rantanplan said:


> I own a Voltcraft VC840, which looks identically to the UT60E, for a couple of years now. I´m not an electonics expert and therefore use it only for simple tasks too, but I´m quite happy with it. It´s very reliable and tough too, imho.
> 
> I also have a Voltcraft VC940, which is more accurate and has the capability of doing power measurements on AC line. But apart from that, it has its flaws ... buggy "software", cheap build quality ... and it´s nearly twice as expensive as the VC840 .



With software you mean the software you install on the pc? 
I didn't expect that the VC940 (looks like a UT71 with RS232C interface) would have a cheaper build quality compared to the VC840. That's a real shame.


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## selfbuilt (Apr 3, 2008)

Raymond said:


> The UT60E does what I want, and is cheap.


I've used a UT60A for about 7-8 years now, and it has worked reliably all that time. I believe it's pretty much identical to the UT60E, but without the temp sensor.

I still use this meter regularly for all my runtime datalogging. Like you, I just open the saved datalog in excel and generate all my graphs there. The original datalogging software that came with it was pretty buggy, but V2 of the software has been stable and reliable (downloaded from their website - came out in 2005?). 

It's currently connected through a RS-232 serial port, but I've used a USB adaptor before for my notebook and it worked fine.

It's been a good performing unit for me. :thumbsup:


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## Crux (Apr 3, 2008)

I'm unfamiliar with the Uni-T but they look similar to those at Tenma.com. I use the Temna 72-7735, about $45 from Newark.com.
No TRMS or backlight, but RS232, good low current (AC and DC) and relative mode.


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## rantanplan (Apr 3, 2008)

Raymond said:


> With software you mean the software you install on the pc?
> I didn't expect that the VC940 (looks like a UT71 with RS232C interface) would have a cheaper build quality compared to the VC840. That's a real shame.



ups, yes, that was a bit misleading. I meant the DMM itself ... sometimes it crashes during power measurement mode, the Min/Max warning function doesn´t work because the setup procedure is messed up. Maybe there are newer and better revisions out there now, mine is a bit older.


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## altis (Apr 3, 2008)

I've had two Tenma instruments and they've both gone back - truely awful kit!

For a day to day DMM I use a Wavetek Meterman 38XR - apparently now called the Amprobe 38XR-A. This has lots of good features and an has an optically isolated RS232 connection and descent logging software. My only problem with it is the safety collars inside the terminals are breaking up. This doesn't effect the instrument it just means I have to shake the bits out from time to time.


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## Raymond (Apr 3, 2008)

What tenma models did you have?


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## altis (Apr 3, 2008)

Raymond said:


> What tenma models did you have?


72-7290 combined PSU, signal generator, multimeter, frequency meter (only useful as a doorstop). More details here:
http://www.imetex.com/html/product/product_model_detail.asp?idx=32

Some handheld oscilloscope - I forget which one. It worked but I managed to lock up the contrast by driving it off the end of the scale. Awful user interface and crappy leads too. It might have been this one or something similar:
http://www.imetex.com/html/product/product_model_detail.asp?idx=2


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## Tidra (Apr 3, 2008)

How about those,...

http://cgi.ebay.co.uk/Digital-Profi...ryZ83646QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

http://cgi.ebay.co.uk/Digital-PC-Mu...ryZ83646QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


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## __philippe (Apr 3, 2008)

The meter in the second URL above looks rather good value.

It is also available from a US seller here:


http://cgi.ebay.com/V-A-PC-USB-Inte...ryZ25412QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Cheers,

__philippe


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## PEU (Apr 3, 2008)

Raymond said:


> How do you consider the UT71B better?


More options, more ranges, native USB, etc.

Where can I find alternative softwares for these multimeters?


Pablo


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## N162E (Apr 4, 2008)

Has anyone tried or had any experience with the Protek D620? http://www.web-tronics.com/pr10coprdalo.html Yes, I realize it is fairly expensive but it appears that it may be a quality all round DMM. I have in mind some Delta-V testing and this tester looks like it might be well suited.


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## Raymond (Apr 6, 2008)

Thanks for the tip on the V&A meters. They look very nice.

After all the info here, I'm now trying to decide between these meters:

V&A VA18B, budget option, and easily available in europe (about €55 shipped)

Uni-t UT71D, most options, most accurate (according to specs), but available from china/hongkong only, about $170 shipped, €135 delivered)

Common sense says that the VA18B is the smart option. But my gut says that I'd always whish that I'd gotten the UT71D.


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## freedom2000 (Apr 6, 2008)

Raymond said:


> Thanks for the tip on the V&A meters. They look very nice.
> 
> After all the info here, I'm now trying to decide between these meters:
> 
> ...



Hi Raymond,

Quite expensive the second one ...
BTW, as you are living in Europe, and with this first name, are you French ?

JP (Jean-Pierre) :wave:


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## Raymond (Apr 6, 2008)

Hi,

The second one is indeed more than 2x the price of the other one. I'm still in doubt if I need the features of that second one. 

I'm Dutch, not French


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## freedom2000 (Apr 6, 2008)

The V&A seems to be very good !

Bye Raymond from Holland (we have exactly the same firstname here in France !)

JP


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## Raymond (Apr 6, 2008)

I've decided 

I can think of too many scenarios where I want to capture data, without depending on a computer to record the measurements. So I've decided on the UT-71D 

A few of those scenarios:

-measuring output current (voltage over output transistors) in an amplifier (other hobby of mine).
-measuring charge/discharge curves of batteries
-graphing temperature over time (for batteries, amplifiers etc)
-taking several measurements and saving the values, without having to write them down. 

I'll order it soon.
Thanks for all your help


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## Raymond (Apr 9, 2008)

Just clicked the "buy it now" button 
I'll let you know how I like it, when it arrives. 

Be prepared for lots of graphs, when start fooling around with it


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## PEU (Apr 9, 2008)

Today I purchased a couple of Unitrends, an UT30A ($25) and an UT30D ($11) needed them for some simultaneous measurements. The UT30A is a very nice unit for its price.

Hope you like your UT71, I use mine on a daily basis.


Pablo


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## Burgess (Apr 10, 2008)

_


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## PEU (Apr 10, 2008)

PEU said:


> Today I purchased a couple of Unitrends, an UT30A ($25) and an UT30D ($11) needed them for some simultaneous measurements. The UT30A is a very nice unit for its price.



Oops I meant UT33A and UT33D, the prices are OK


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## Raymond (Apr 10, 2008)

It's too bad that shipping usually kills the deal, otherwise there are some really nice DMM deals to be had on Ebay. Especially the DMM's of the "lower" ranges from unitrend or that V&A DMM. $30-$45 for a DMM with nice features, is a very good price  But add $30 shipping on that, and it kills the deal.


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## N162E (Apr 10, 2008)

Raymond said:


> Just clicked the "buy it now" button
> I'll let you know how I like it, when it arrives.
> 
> Be prepared for lots of graphs, when start fooling around with it


I just ordered the Protek D620 http://www.web-tronics.com/pr10coprdalo.html I am looking forward to comparing some results. My first order of business will be to test Delta-V sensing of the LaCrosse and Maha chargers.


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## Raymond (Apr 18, 2008)

It arrived last wednesday! It's big compared to my Fluke 23-II  
It's not as fast as I hoped (refreshes/second), but it's fast enough. A memory for 10K measurements is really handy. I can simply set it up next to all the other equipment, record the data and later on transfer it to the pc. 

Here's a pic of the DMM in action (measuring voltage over an old 750mAh duracell which is discharging @ 500mA)






Here's a charge curve of my ultrafire WF-138A:




(I have more rcr123s on the way, and will post an image with the charge curves of all my RCR123s when I can)

Here's a graph with a charge/discharge curve of a (bad) nimh batt, charged by the ansmann in the pic above:






I think the delta-V is quite clearly visible. The neat thing is, is that the charge current is not all that constant, and the values appear to jump up and down when you look at the screen of the charger (and it's also visible in the graph). But the average of a few measurement point is constant, and apparently, the charger has some averaging built-in or something 
The discharge current is very constant, also clearly visible in the graph. 
The first 3 minutes of the graph are correct: I can set the capacity of the cell independently from the charge current. So I enter 750mAh, charge current of 500mAh (I think that I used that), and the first 3 minutes the charger charges at 1C, to test the batt and after 3 minutes, switches to the configured charging current. 

Great toy 

In another topic, I read a post by Silverfox that cheaper/lower quality li-ion batts develop a high internal resistance after some (10 I think he wrote) cycles. I will test my trustfire 18650s, to see if they show that behaviour.


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## N162E (Apr 18, 2008)

My Protek D620 http://www.web-tronics.com/pr10coprdalo.html Arrived yesterday and I am hoping to get some testing up and operating over the weekend. It is also a bigger unit than I expected. My first order of business still is to observe and verify Delta-V sensing of the LaCrosse and Maha chargers. Ray, I'm glad to see you got things rolling.


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## Veto (Apr 19, 2008)

I bought one from Multimeter Warehouse and have been very happy with it. I paid ~$50.


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