Ok, let's continue with the review! First, some exterior pics:
The UT171B comes in a nylon bag. In it you'll find the meter itself, the probes, a temperature probe (beaded K-type), the wall-wart and an adapter for charging the battery, and a CD with the software.
The device is large, but not huge. Compared to two other meters that are popular on these forums, you'll see that it is taller but not thicker, and with the beforementioned rounded back it feels good in the hand.
I've made a series of photos of the
display at different
angles, with an UT61E next to it for comparison. What you can see is that the UT171B's display has higher contrast, but reflections on the protective cover can be problematic. Also, you can see the color inversion effect. In the last pictures, I'm standing hunched over the meters to photograph them, blocking a lot of light in the process. Whereas the standard LCD display suffers from this and becomes hard to read, these low light conditions help the EBTN display of the UT171B.
On to some
measurements! I have here a chinese
voltage standard which I think is accurate to 0.1mV, let's see what the meter says!. In DC mode, the meter is specced at 0.025% + 5 counts accuracy for the 6V and 60V ranges we'll be using.
UT171B -- Reference -- Error2.4988V -- 2.49894V -- 1 count
5.0015V -- 5.00167V -- 1 count
07.500V -- 7.50014V -- none
10.002V -- 10.0024V -- none
For
resistance measurements, I have some precision resistors accurate to 0.05% (Vishay PTF56 and PTF65 series.) The accuracy of the meter for measuring resistance is specced at 0.05% + 2 counts. Unfortunately, those resistors aren't really good enough to determine whether the meter is in spec or not. They will let me observe how the meter drifts over time though. For now, let's just see what the meter measures:
UT171B -- Resistor Value 49.99Ohm -- 50.00Ohm
1.0002Ohm -- 1.0000Ohm
9.998kOhm -- 10.000kOhm
100.00kOhm -- 100.00kOhm
This is a
datalogging multimeter with internal storage for up to 10000 measurements. When you long-press the STORE (Rec) button, you enter datalogging mode. It asks you for a logging interval between 1 and 240 seconds, and then for how long to log for in minutes. That duration is limited to the number of minutes it takes to fill the memory of course. Inputting the numbers happens with the arrow, +/- and OK keys and is easily done.
When it's logging a data point, the [STO] indicator lights up briefly. It also displays the remaining time in the secondary display. If the secondary display is used for another function (e.g., frequency in Vac mode,) the display will alternate every second or so.
Nice: auto power off is disabled in data logging mode, and is the automatically reenabled when datalogging ends.
Not so nice: you can review the logged values in the meter by endering RECALL mode and using the arrow keys. It does not tell you what your logging interval was however, so you need to remember that. The UT171C is better in this regard, since it has a clock and stores timestamps with the values, at least according to Uni-T's website. Unfortunately, this leads to a problem when using the
software:
What I've done here is data log for one minute at 1 sample/sec (fastest speed), stopping at approximately 13:52:40. While it's datalogging, the meter keeps sending the currently measured values to the software at about 5 measurements/second, and the software helpfully plots those values. Afterwards, I recalled the stored values using the software, and here's the problem: You can't tell the software what the measurement interval was, it proceeds to assign the current time to the replayed data points, so you end up with 5-ish datapoints per second. Indeed, you can see that in the graph there, those two dips on the right are the replay of the one of the left; they're condensed but shouldn't be!
The workaround of course is to export the tabular data, completely ignore the DateTime column and assign your own time offset using the recording interval you chose (hope you remember it!)
And yes, transferring recorded data is slow. If you need to transfer all 10000 data points, expect to wait about 30 minutes.
Otherwise, the software seems to work. I tried switching through the modes, and it seemed stable and functional. It has various buttons that let you change anything you could change on the meter using the buttons, but it doesn't let you virtually turn the rotary wheel of course. So those red labels in the screenshot are pushable. In case you're wondering, "Value Model" simply means relative mode. It lets you actually enter the offset value manually, which is nice.
The values in the software are updated at display update speeds, this unfortunately includes the bar graph, so you get 5 updates per second for that too.
Btw, the adapter Uni-T supply isn't actually a simple USB/Serial adapter like I expected, instead it shows up as an USB HID device. This makes reverse engineering the protocol slighly more difficult and means you can't just hack up a simple python script to do your own data logging, pity. The advantage is the software just works when you press "Conn", no need to figure out which serial port is the right one. It also means that at this point I see nothing to indicate that the software supports more than one connected meter. Might be possible by connecting one meter first, then starting a second instance of the software and then connecting the second meter. The software does not work under wine.
Some observations about some
secondary functionality:
- Relative mode and Min/Max mode disable autoranging.
- This meter does averaging in Min/Max mode.
- Min/Max mode does not increase measurement speed as it does on some other meters. Also, only the secondary display is used for displaying the Min/Avg/Max results, so you lose a digit of precision there.
- There is no auto hold or delayed hold like on the UT61E, but since there's no overshoot, Min/Max mode can serve as a replacement.
- Peak hold only works in AC mode and really can only be used for recording AC waveform peaks.
- The bar graph update rate seems to be 20Hz. A sine of that frequency will result in the bar graph showing a constant value in DC mode.
Ok that's it I think. If there's anything more you'd like to know, let me know.