M-Bus to emonHP readings stop working

Hardware
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1

Every so often, I find the results from the heat meter fed by the M-Bus reader connected to the emonHP stop. I have seen the readings restart like the one below without intervention. To manually restart it, I found I just need to unplug and plug back in the M-Bus reader from the emonHP. I thought it might be a power issue with the emonHP but it’s only drawing around half an amp. Has anyone else seen this?

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FYI - I’m using the USB A on this power adapter to power it 40W USB C Plug Fast Charge, UK 4-Port Multi USB Charger Plug Fast Charging Plug for iPhone 16 15 14 13 12 11 Pro Max SE XS XR Plus, iPad, Samsung Galaxy,Dual Port USBC Power Adaptor Type C Wall Plug: Amazon.co.uk: Electronics & Photo

2

Check the MBUS cable is routed away from other 240V cables, this can cause interference but this is rare.

The RasPi4 needs 5V 3A not all USB A to USB-C cables can handle this, check the cable is not the bottleneck. What happened to the supplied adapter? I would highly recommend using the original power adapter.

You could try using a different USB cable for the MBUS adapter? Just in case it’s a cable issue. I’ve had a look at your data, it doesn’t look like the issue happen infrequently.

3

Thanks Glynn - I route all data cables at least half a metre away from mains power. There are only some 5V cables next to it, so I tried moving the M-BUS adapter to a different position.

The power cable is not long enough on the supplied adapter so I used a power supply designed for 3A and cables designed for 5V/3A UGREEN 2 Pack USB C to USB C Charger Cable 100W 65W USB C Fast Charger Cable Compatible with MacBook Pro M3/Air, iPad Pro/Air, Dell XPS, iPhone Air/17/16 Pro Max, Galaxy S25 Ultra, Pixel 9 (3M) : Amazon.co.uk: Computers & Accessories. I did check whether there was a voltage drop with one of these and found it draws around half an amp: USB C Tester Power Meter 2 in 1, YEREADW Digital Multimeter 3.6-32V 0-8.0A Voltage and Current Tester Meter, Type C Voltmeter Battery Capacity Ammeter Power Bank Fast Charger Detector (USB Tester) : Amazon.co.uk: DIY & Tools .

I did hunt around for Pi adapters with longer cables, but there don’t seem to be any available.

4

It sounds like the power supply should be fine then.

You could try a different usb cable ife the mbus reader if you have a spare USB-C to USB-A?

5

Thanks Glynn - I moved the adapter and will try a cable change if that does not do it.