Author Topic: find a nice and cheap USB color display tester with communication function  (Read 4891 times)

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Offline RD Tech

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Today, we will publish new product USB color LCD display tester meter.
https://www.aliexpress.com/store/product/RD-USB-2-0-Color-LCD-Display-Tester-voltage-current-meter-4-digit-Voltmeter-Ammeter-Temperature/923042_32845522857.html
User manual and PC software download link: http://www.mediafire.com/folder/0jt6xx2cyn7jt/UM24
Simple video to show this : https://youtu.be/nIZSb0DJExc
There are 2 versions, UM24 (no communication version) and  UM24C (communication version by Bluetooth)
there are many advantages: 7 main interfaces, 10 kinds date detection, operation help button, PC bluetooth connection, 10 data groups to store, Micro USB cable impedance measurement, voltage and current graphing…
Now as old rules, at first published 4days, selling at lowest price 9.99 usd (UM24)? 12.99 USD (UM24C), after 4 days, back normal price more than 13 USD ( UM24), 17 USD (UM24C).
In the market, same quality and color LCD USB meter cost more than 20 usd. So please check it, hope you like it 
If you don’t like it, please ignore me
Have a nice day
Best Regain
Glen
BTW, home page : https://rdtech.aliexpress.com/store/923042
Power supply page: https://rdtech.aliexpress.com/store/group/Power-Supply-module/923042_252253169.html
« Last Edit: December 13, 2017, 01:20:09 pm by RD Tech »
 

Offline scorillo47

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Very nice device.

I succeeded to connect the Bluetooth interface and it works (including exporting data to clipboard)

Bluetooth connectivity seems to go down after a few minutes though when the screensaver goes dark. After disabling the screensaver (to zero minutes) seems to work for the last 10 minutes or so

Thanks
« Last Edit: January 10, 2018, 12:39:57 pm by scorillo47 »
 

Offline scorillo47

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Quick question - what is the serial protocol on ports COM3/COM4? I tried to connect to it with Putty and didn't seem to work

Thanks
 

Offline RD Tech

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could you make a video to show this problem
 

Offline RD Tech

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what's your computer ? did you use the bluetooth adaptor ?
 

Offline scorillo47

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Hi,

Here is the video. Issue appears at around 1:20

https://www.youtube.com/watch?time_continue=116&v=_5z387RGT5w

Things I've noticed:
- this is using Bluetooth as a way to connect the PC to the tester (is there any other way?). I am using this Plugable Bluetooth dongle. Computer runs Windows 10 with latest updates https://www.amazon.com/gp/product/B009ZIILLI
- As can be seen in the video, it happens only when the Auto screen off is enabled and right when the device screen goes black. The LED remains solid red, so the Bluetooth connection is still active. Also, if I wake up the device, it still shows values being monitored, but the PC application shows zero values.
- this seems to happen 100% when the device is in horizontal position. Doesn't seem to happen when the device is hanging vertically from the monitor (?). Perhaps it's possible this is caused by weaker Bluetooth signal? Although this is unlikely as my Bluetooth adapter is very close (about 1 meter - 3 ft). 
-

All this indicates some sort of software bug with the Bluetooth stack.

Would be nice if the tester would show somewhere the Bluetooth signal strength.

The workaround seems to be to disable "auto screen off" and let it run constantly. I have it ran for several days in this configuration without issues. But now the tester consumes more power constantly.

(BTW, just to be clear - this is a GREAT device. The problem I am describing is a minor one)

« Last Edit: January 16, 2018, 08:28:18 pm by scorillo47 »
 
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Offline blueskull

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A small marketing tip: don't use a 12'' Macbook in your picture wile stating software is for Windows only. That sounds like you have a worship to the Apple God, and AFAIK a lot of engineers get pissed off by that.
 
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Offline scorillo47

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Hi,

In addition to the earlier minor bug I found another one which would be good to fix.

I am doing something simple - I am monitoring the discharge of a Li-ion battery pack, through the tester and to a load. The tester runs with voltage from the battery pack, which at some point dies. The problem is, when the battery pack dies, the software "forgets" the cumulative metrics such as mAh/mWh which now become zero. So now I cannot tell anymore the total mAh that the battery pack generated.

Here is a screenshot illustrating the problem - capacity record and energy record have been reset to zero.



 
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Offline ddanijell

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Re: find a nice and cheap USB color display tester with communication function
« Reply #8 on: February 13, 2018, 11:16:02 am »
Today I got um24c, a great product!
Android application works fine.
On pc as I use linux and I can not run the windows app.
I connected via BT and I tried to connect via putty and minicom to /dev/rfcommX, but unfortunately I should probably send some initials sequence to um24c device?
I tried baud rate 9600, 38400 ... 115200 but um24c does not seem to send anything until it receives an init sequence? It would really be useful for me to use the BT serial port to get the parameters that I could log in to file to later analise.
Is there any chance of getting the necessary data for the init sequence and the required com port parameters?
Thanks in advance !
 
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Offline piotrva

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Re: find a nice and cheap USB color display tester with communication function
« Reply #9 on: February 17, 2018, 07:34:56 pm »
@scorillo47 Please read the manual - for measurement group 0 the data is deleted a few seconds after next power-up. If you change to other group (1..9) the data will be stored until you clear the group. Also - everything on your screenshoot is set to 0 (even temperatures). Maybe you are suffering an issue with communication with the device, mentioned earlier?
@ddanijell I have done some reverse engineering on the protocol.
1. The baudrate you set over bluetooth is not taken into account - this is only virtual baudrate, and physical output baudrate at the meter board is fixed. Original software sets baudrate to 9600, no parity, 1 stop bit, 8 data bits, no flow control.
2. The UM24C protocol is not a character protocol, but it is binary protocol. As you send byte 0xF0 You will get some bytes in replay. I am attaching some results of my work, maybe someone will write a custom app to drive this tool.
3. Also maybe if you buy version W/O bluetooth you can use RX and TX pads on main board.

I do not guarantee anything about presented information - as this is not official documentation you are using it on your own risk.

@RD Tech - maybe you will publish official documentation of the protocol, as i have not been able to figure out meaning of some bytes. Also can you publish LabVIEW source code of the app? I think the error mentioned above is LV related, rather then device related. I have to admit that device is well manufactured - all PCB edges are clear, enclosure fits perfectly. Also connection between main board and BT board is done nice.



« Last Edit: February 19, 2018, 02:57:52 pm by piotrva »
 
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Offline ddanijell

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Re: find a nice and cheap USB color display tester with communication function
« Reply #10 on: February 19, 2018, 08:24:57 am »
Thank you, you did an excellent job !
That's what I was looking for !
I just tried in bash shell direct write and read bt/com port and that's what I needed to read the data from um24c.
It works great and the table you sent has eased the job.
I really thank you very much!   :-+
 
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Offline piotrva

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Re: find a nice and cheap USB color display tester with communication function
« Reply #11 on: February 19, 2018, 03:14:30 pm »
You're welcome. As I will have some free time maybe I will develop custom application in Python or LV.
 
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Offline bflores

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Apologies if a dumb question. But, are these USB current meters, monitoring current only, and a pass through for serial data? Or is their intelligence in between, possibly effecting the serial data?  I.e. Are they USB 2.0 / 3.0 / 3.1 agnostic?
 
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Offline NiHaoMike

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The data is pass through on most of them, although there always will be some reduction in signal integrity.
Cryptocurrency has taught me to love math and at the same time be baffled by it.

Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 
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Offline RD Tech

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Hi,

Here is the video. Issue appears at around 1:20

https://www.youtube.com/watch?time_continue=116&v=_5z387RGT5w

Things I've noticed:
- this is using Bluetooth as a way to connect the PC to the tester (is there any other way?). I am using this Plugable Bluetooth dongle. Computer runs Windows 10 with latest updates https://www.amazon.com/gp/product/B009ZIILLI
- As can be seen in the video, it happens only when the Auto screen off is enabled and right when the device screen goes black. The LED remains solid red, so the Bluetooth connection is still active. Also, if I wake up the device, it still shows values being monitored, but the PC application shows zero values.
- this seems to happen 100% when the device is in horizontal position. Doesn't seem to happen when the device is hanging vertically from the monitor (?). Perhaps it's possible this is caused by weaker Bluetooth signal? Although this is unlikely as my Bluetooth adapter is very close (about 1 meter - 3 ft). 
-

All this indicates some sort of software bug with the Bluetooth stack.

Would be nice if the tester would show somewhere the Bluetooth signal strength.

The workaround seems to be to disable "auto screen off" and let it run constantly. I have it ran for several days in this configuration without issues. But now the tester consumes more power constantly.

(BTW, just to be clear - this is a GREAT device. The problem I am describing is a minor one)

thank you for your reply, because I did not know more how to use this blog, I did not say your reply
for your problem , it should be bluetooth adaptor problem
. for desktop, when you use the bluetooth adapter to make bluetooth connection, Please don’t use the adapter own driver, and use the windows system bluetooth driver, otherwise the module can’t make SSP series port communication. If you have installed the adaptor driver, you can uninstall it and unplug the adaptor, then plug in again, the system will install it automatically.
 

Offline RD Tech

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thank you for your remind , I will take care about those details
 

Offline RD Tech

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sorry, friend
we don't provide protocol, it is only support windows and android
 

Offline RD Tech

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thank you for your support
 

Offline RD Tech

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I am waiting
 

Offline RD Tech

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now just measure
 

Offline ddanijell

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sorry, friend
we don't provide protocol, it is only support windows and android

You answered after a very long time, and you did not say anything. You hide the protocol as if it were a recipe for an atomic bomb ?!
 But i have this protocol, dont worry, and thanks for nothing !
Thanks again @piotrva .
 

Offline RD Tech

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because there is not message to remind that there is message , I just see today
we can provide DPS protocol. for UM seriese, we don't provide , because it is easily to be changed to lead not work, for safe, we don't provide
please calm down
 


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