Annex RDS forum

A few months ago I bought a multimeter at the Lidl supermarket chain. The Parkside PDM 300 C2.
I could not resist because it seemed very cheap: Then I have seen on the Internet that it seems very easy to hack it, since it has an accessible serial port and it can be easy to combine it with an ESP8266 module (and Annex, of course) to control our measurements on a Web page. For example, the variation of consumption down to micro amps.
My problem is that I do not understand the German language and there is a specific page, which, I do not know why, Google does not translate. It is this:
https://www.mikrocontroller.net/topic/4 ... to=new#new
Please, can a German-speaking colleague read it and give their opinion on whether what they propose is feasible?
Thanks.
https://www.mikrocontroller.net/article ... C2_Analyse

I found this to convert in spanish

http://translate.google.com/translate?u ... 8&oe=UTF-8


http://translate.google.com/translate?u ... 8&oe=UTF-8

Very thankful, Francesco.

i can help.

[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Sat May 15, 2021 3:32 ami can help.

I appreciate it, Panno.
The multimeter opens easily, with just four screws and without the obnoxious plastic tabs.
I have soldered a fine two-wire cable: one to the point of the printed circuit printed as TX and the other to GND. I have taken it outside through the female terminal marked 10 Amps.
My intention is to directly connect this cable to the RX (GPIO3) and GND inputs of an ESP8266, powered at 3.3V.
In the articles of "mikrocontroller" it seems that he warns against never making such a direct connection, and proposes to insert an optocoupler.
Questions:
Can you investigate me why they say this? Is it just because they connect the multimeter to the PC via a serial-USB converter?
Or because if alternating voltages of 230V are measured, it can be dangerous for the PC?
I only plan to use this system to measure currents and small voltages in direct current and it seems to me expensive and that it unnecessarily complicates the project the use of optocouplers (the one they recommend, with transport costs, would cost me more than the complete multimeter).
It seems that the multimeter delivers a serial signal to 2400 8N1, although I also see someone quote 9600. Does it talk about the voltage level of the signal somewhere? 5V, 3V3 or something exotic?
Any advice on this project is welcome.

HI ;

first of all : you need to use a high voltage optokoppler because the input from MM and the ground from THE INSIDE SERIAL Port are Connected ! this means you have full voltage here . this will kill your pc and maybe your live !

Original :
Ein optoisolierter Wandler ist hier praktisch
Pflicht, da der Multimeter über den Ground-Pfad des Serialports mit dem
Ground des Computers und damit mit PE verbunden wird. Es besteht eine
hochimpedante Verbindung zwischen dem Digitalground des Multimeters und
den Eingangsbuchsen!

so please be patient ! even if you will use small voltages i recommend an optokoppler.

Ok , ive read the full Thread

All in all if you use the optokoppler you can read voltage up to 60V. Inside the MM are some problems with some "near" pcb wires.this is why only 60 V are recommended.

A Wireless Bridge (with ESP) inside a safe Case (3d printed) solve the problems.no wires outside is the best.
Another Problem is some pc's have some voltage on the tower (ground) (apple like ) . so i recommend a Optokoopler also.

to test the system without optokoppler you can use 0-3 volt on input. the MM sends data with 2400 baud. 3,3 volt

Fernando ! ARE YOU ALIVE ?

[Local Link Removed for Guests] wrote: [Local Link Removed for Guests]Mon May 31, 2021 9:05 pm Fernando ! ARE YOU ALIVE ?

Panno, I appreciate your interest. I am not dead yet, although I am working on it! Now seriously, I have not advanced anything in this project and I have it stopped.
I have downloaded all versions of the ParkSideView program and with none of them I get a response from the multimeter.
However, through a serial port communications program, for example Putty, if it is seen that the multimeter sends data regularly and continuously.
Possibly it is because my version of the Parkside is different from the one used by the author of the program and has changed the communication protocol.
My initial idea is to use the code available on Gitub to adapt it to Annex, but if I have to start practically from scratch and try to interpret the meaning of the character strings that my multimeter delivers, it seems to me an excessive work for the result that I could obtain.
And mainly, I don't know if I would be capable.
Thank you again and forgive me for lost time.

Hmm , maybe you found a later a solution.
Btw : no Time ist lost because helping people make the world a little better ( sometimes )

Gtx