Products > Test Equipment

Brymen IR connection protocol - Anyone sniffed it yet?

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macboy:
I can't speak to the Brymen specifically, but I have a handheld meter with an IR serial interface, a B&K 5360 (aka Metrix mx56c). There is no special modulation or data format, the data on IR is just vanilla UART style serial, no additional carrier (like a TV remote control) or anything. I used a USB-TLL serial converter (PL2303 based), with a IR diode and current-limit resistor for Tx, and a phototransistor and pull-up resistor for the Rx. Very simple. Sometimes the simplest answer is the one.

pradipkhare:
I recently bought the Brymen BM869 along with the s/w and interface USB cable pack.

Supplied s/w on the CD was not getting installed on my Windows-8 Laptop due to the version issue. I downloaded the Win-7 version (that is the recent they have) from the Brymen's website. It got installed and working fine now.

For installing USB interface driver, I needn't require to install it separately, as when I plugged the usb cable in, Windows automatically detected and installed the driver and protocol from the already inserted CD.

I am using it successfully and baud-rate is enough for all types of logging. It also shows a nice wave form. You can log data for all the parameters that can be measured using this multimeter. I also used export-to-CSV file feature successfully and were able to do additional analysis using the Excel.

It is working fine and has an excellent accuracy. I love this multimeter and recommend to everybody looking for an advance DMM. :-+


Dave,
Thank you very much for doing the review of this meter, as from there only I got to know about Brymen and bought this.

Regards,

Simon Loell:
@Jadew / others.
Did anyone start monitoring this IR protocol?

I have both the BM869 and the USB/IR interface.

I don't know much about USB communications, but the IR part should be a bit more simple to sniff.

What is your main purpose of knowing the protocol?

If it's making a new PC interface for it, it would be GREAT! I use my multimeter for logging temperature a lot. It has 2 temp inputs, but in the PC interface only T1 is displayed. A huge bug in my opinion.

-Simon

jadew:
I tried sniffing the protocol, but not knowing the handshake doesn't get you anywhere, because the meter won't start transmitting, even if it's plain UART :)

@Simon, yes I'd like to make an IR interface, since I'm too cheap to buy an original one :P which honestly... it's super expensive for what it is.

As for the USB communication, I wouldn't worry about that too much at this point. The first step is to establish serial communication with the meter, in order to get some usable data out. The HID device should be fairly easy to implement.

Simon Loell:
Well I hooked my oscilloscope into the Rx and Tx diodes, and my findings are not so obvious I think.
It seems that the data is not UART protocol, but Brymens own. Maybe some direct indication of what segments are active in the display.
In my attached pictures it can be seen that a "1" is represented by two LOW bits, where as a "8" has a hole bunch.

Another strange thing is that the Rx and Tx diodes measure the exact same, and no I did not short circuit anything...

Last but not least. The packages are sent with a speed of approx 5Hz, which is even faster than the PC User Interface can update. It would be very nice with a UI with faster update speed.

I hope you can find some logic in my pictures. Since I have the setup, I'm not that eager to spend a lot of time on this projects. But if you need a reading or two to figure out the puzzle I can give it a try. As long as you're the brain in this backwards engineering ;)

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