Products > Test Equipment
Metrahit USB-IR DIY interface
noidea:
--- Quote from: 0xdeadbeef on June 25, 2015, 06:36:27 pm ---While the above DIY solution only works with the Starline series, I still think a similar solution could be possible for the older models.
The Sigrok wiki contains some interesting information regarding the 1x and 2x models.
Firstly, it states that "the IR signal is just serial data encoded in a SIR-like fashion, not IrDA or SIR".
While this is definitely not true for the Starline series, it might be true for the 1x/2x series even if the manuals of the adapters say it's SIR.
Furthermore the wiki says that the 1x series (send mode only) uses 8192 baud and the 2x series uses 9600 baud on the IR side and that both use a proprietary binary protocol.
It seems that apart from the Starline Series, only the 27I, 27M, 28C and Metraport 40S use a SCPI like ASCII protocol. So testing the IR communication with an 1x and 2x through an ASCII terminal is futile.
However there's a driver available in the Sigrok git repository which might be interesting for those trying to understand the binary protocol.
--- End quote ---
Hi 0xdeadbeef
Sorry to raise this one from the dead, I've just purchased a Metrahit 27i and this post came up when I searched for info on the USB IR interface.
I also found your IrDA USB project and was wondering on what you thought of my chances of being able to communicate with the 27I were before I go down the path of modding it to suit the older style casing and getting a PCB made and building one.
Thanks if you can help.
0xdeadbeef:
The Sigrok Wiki says that the 27i uses the same text style protocol as the newer "Starline" multimeters but also that it uses a different adapter, namely the BD232 or USB-Hit.
It also says that for these adapters "the IR signal is just serial data encoded in a SIR-like fashion, not IrDA or SIR".
I was told though that the BD232 uses "raw" IR without any encoding. Can't really provide any more details though other than some guy said he got it working with just an off the shelf USB to serial converter and a discrete IR diode circuit.
So I tend to say that my adapter (which kinda replicates the "USB X-Tra" adapter for the Starline series) most probably won't work as replacement for the older adapters like BD232 or USB-Hit.
VeniBenja:
Hello there, I have two very old Gossen Megawatt multimeters. A 16S and a 18S. The 18S had a lot of problems with the display. I couldn't read it any more. So i decided to open it and try to fix it. The fix where two stripes of paper on the LCD. With the liitle more thickness the rubber conection get much better contract. Now the quality is like a new one again. Because i had the multimeter already open i did some experiments with the IR interface. In this old meters it's just an unidirectional interface for sending data. I pushed the data and on butten and it start sending. I could see it with my phone. The IR LED is on a small board with 3 conectors. I mesured them. The one with the + is the data connector. It's the same for both multimeters. I connected it with the RX pin of an Arduino and piped the output to a terminal. I could direct read some symbols. After changing the configuration to 8192 Baud 6N1 i was suprised to see values in plaintext. Of course it was value of the actual mesurement. I didn't expect that it was so easy. The best is it works for both 16S and the 18S the same. :-DD :-DD :-DD
Next step i could test to connect it to the offical software. Also i think to buy some IR interface to make the original connection or maybe a ESP32 to integrate it in the case to have a bluetooth and wifi meter. Maybe i can use the powersupply for the IR LED for the controller.
Update: Sucessfully testet to connect my metrahit 16s 18s and 22s with Arduino Mega and read out data with sigrox driver.
Update2: The easiest and cheapest way to build an IR intervace for the Metrahit 1x 2x series seems to use a cheap IR distance sensor such as HW 201. It's just a fototransistor and comparator with IR LED. The IR LED could be used for the serial comunication but actually i just use the transistor comparator combo. I connected the output of the HW 201 to my RX pin. There is a poti on the HW 201. It's normally used for the distance threshold but i used it to get the correct UART Signal. I used an oscilocop to visual the Sigal, it's but you can also do it blind with opending the meter with sigrok and tuning the poti until you receive correct data.
I testet it on linux and windows on windows it doesn't work for some reasons. maybe the diver of the USB serial adaptor doesn't work with this strange baud rate bit combo. i also tested differend USB serial
plugs. The CP2102 doesn't work. The Ardunio Mega 2560 worked well also the pl2303.
thelastdodo:
Just wanted to let you know about another success story using the cheap alternative "Irdroid USB irDA Transceiver".
To make the mounting easier and robust, I created and printed a littel adapter:
https://cults3d.com/en/3d-model/tool/infrared-to-usb-adapter-mount-for-starline-metrahit-am-pm-a-e-s-series
It can be seen in action here:
https://youtu.be/wjbuir5mLuA
Greetings and happy tinkering!
horo:
--- Quote from: 0xdeadbeef on January 02, 2018, 10:44:12 am ---I was told though that the BD232 uses "raw" IR without any encoding. Can't really provide any more details though other than some guy said he got it working with just an off the shelf USB to serial converter and a discrete IR diode circuit.
--- End quote ---
That's true for the MetraHit 2x devices. See also the Gossen document Interface Protocol for METRAHit 22-29S/M Multimeters. I used this info together with the sigrok code to develop my project OpenMetra, already mentioned in this thread. :-DMM
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