The part number implies a device produced specifically for Mitsubishi .
I’m inclined to agree. Looking at the Manual, the ‘frequency’ part 5.1.1 does not include ‘optional’ in the description, implying it is available on all devices.
Under section 5.1.5
The frequency output can be wired together with the optional functions. However, not every
combination is possible.
In principle, the pins 2, 4 and 5 can only be assigned with one function at a time. A multiple
assignment is not possible.
That I think is poor translation and means that only one of the pins 2, 4 or 5 can be used at any one time.
Thanks. I will have a closer look later and put a multimeter on it.
Interestingly I managed to find the bit in the Ecodan manual for the flow meter. It only references an analogue reading, not the pulse.
So, I am thinking that the pulse is part of the standard flow meter, but has been labelled as ‘do not connect’ as this is an OEM meter and the pulse would never be used within an Ecodan installation.
You didn’t mention that before!
Yes, I think you may well find a pulse there, but the comment about pin use might mean it’s custom software and it’s not included.
If that’s the case, if you’re careful then monitoring the voltage output will probably still work, but you must make sure that everything you use to do that is isolated from everything else except the heat exchanger - i.e. you use an isolated mains supply to your Arduino and opto-coupler or radio to get the data out.
Thank you. I have setup a Arduino to read a handful of DS18B20 thermometers and issue the data via MQTT. I aim to get this setup over the next few weeks.
Happy to share the code if anyone wants it.
I am then going to get a oscilloscope and test the output of the flowmeter. I suspect that I will find an unused pulse, which I can connect via an optical coupler to a second Arduino.
@gck303 - George, did you connect your VVX20 Mitsi to your EmonTx3 in the end? I have an identical (Ecodan) pair of pumps, and am trying to connect to an EmonTx via the digital output . Any insights follwing on from your Jan post would be really helpful.
I guess plan B would be to assemble the dedicated board, which is where your post started off…
To intercept the signal from the flow sensor while the sensor is plugged into the ASHP controller we need to make a mini PCB adaptor. This is the plug that my Samsung branded VVX sensor came with, can anyone identify what plug this is and what connector will be required to plug into it?
@gck303 can you confirm if your Mitsubishi branded VVX has the same connector?
It’s a silly question - is there nothing anywhere on the moulding? Knowing the pin spacing and physical dimensions might allow you to narrow the choice down. It almost looks automotive.
The headers on the PCB look similar - is there any marking on those?
These parts seem to only be available from one supplier in China, I’ve ordered a sample MOQ of 50 PCS. Let me know if anyone wants some for testing?
The eventual plan is to make a little breakout PCB to sit inline between the sensor and the HP controller to intercept the signal from the Sika. It seems this exact same sensor is used in Samsung, Mitsubishi and Vaillant ASHP units, being able to read the flow rate from this sensor will enable us to monitor COP for these units without having to fit an expensive heat meter.
Here’s the pinout of the Samsung sensor, it’s yet to be determined if the Mitsubishi sensor uses the same connector and pinout, is anyone able to check?
I have an Ecodan that I am currently looking to add some monitoring to as I don’t have a level 3 RHI package, and getting the flow rate without the disruption of adding a meter would be very useful. The board on my FT6 looks to be using the JST type plug referenced by Gwil in the post above and the wires are coloured in the same order.
Ecodan’s use a different plug to Samsung. However, the good news is the same connections are broken out on the screw terminals below which makes reading from the Sika sensor much easier.
