# Troubleshooting Flow Meter comms on the Emonpi2

**URL:** <https://community.openenergymonitor.org/t/troubleshooting-flow-meter-comms-on-the-emonpi2/29035>\
**Category:** Installation\
**Tags:** emonpi2\
**Created:** [25 August 2025 11:15 UTC](https://community.openenergymonitor.org/t/troubleshooting-flow-meter-comms-on-the-emonpi2/29035 "2025-08-25T11:15:42Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![rvangraan](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/r/f4b2a3/32.png) [@rvangraan](https://community.openenergymonitor.org/u/rvangraan)\
**Post date:** [25 August 2025 11:15 UTC](https://community.openenergymonitor.org/t/troubleshooting-flow-meter-comms-on-the-emonpi2/29035/1 "2025-08-25T11:15:42Z")

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Hi there,

I’m trying to troubleshoot the following communications issue:

```auto
Aug 25 12:01:00 emonhp emonHub\[2294\]: ERROR MBUS Could not find MBUS device
Aug 25 12:01:00 emonhp emonHub\[2294\]: ERROR MBUS Could not write to MBUS serial port
Aug 25 12:01:00 emonhp emonHub\[2294\]: ERROR MBUS read_data_frame could not read from serial port
Aug 25 12:01:00 emonhp emonHub\[2294\]: DEBUG MBUS Invalid MBUS data received 0 bytes 0.4 ms, count: 1
Aug 25 12:01:00 emonhp emonHub\[2294\]: ERROR MBUS Could not write to MBUS serial port
Aug 25 12:01:00 emonhp emonHub\[2294\]: ERROR MBUS read_data_frame could not read from serial port
Aug 25 12:01:00 emonhp emonHub\[2294\]: DEBUG MBUS Invalid MBUS data received 0 bytes 0.5 ms, count: 2
Aug 25 12:01:00 emonhp emonHub\[2294\]: DEBUG MBUS Decoded MBUS data: None

```

Basically, my heat meter is installed and connected via the MBUS adaptor on the emonpi2. I can see it’s configured for `com_port = /dev/ttyAMA0`

This device exists:

```auto
 pi@emonhp:\~ $ ls -l /dev/ttyAMA\* 2>/dev/null
crw-rw---- 1 root dialout 204, 64 Aug 25 12:00 /dev/ttyAMA0

```

But I don’t see any messages in the log when I plug the dongle in, even though there is a red light indicating power.

 ![IMG_8921](https://community.openenergymonitor.org/uploads/default/original/3X/f/5/f5fa325bb0f59b4b93a6a990dee537c765118fce.jpeg)

 ![IMG_8920](https://community.openenergymonitor.org/uploads/default/original/3X/d/6/d69fdb05f89f50c0478ce1e80c6cc1693fc5d6c0.jpeg)

Is there anything I need to look at? Any suggestions?

Thanks!

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<div class="post-metadata">

**Author:** ![borpin](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/borpin/32/193_2.png) [@borpin](https://community.openenergymonitor.org/u/borpin)\
**Post date:** [25 August 2025 13:42 UTC](https://community.openenergymonitor.org/t/troubleshooting-flow-meter-comms-on-the-emonpi2/29035/2 "2025-08-25T13:42:02Z")

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> [@rvangraan](#):
>
> `Could not write to MBUS serial port`

It might be a permission issue. Other than that, I don’t know, sorry.

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**Author:** ![Robert.Wall](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/robert.wall/32/38246_2.png) [@Robert.Wall](https://community.openenergymonitor.org/u/Robert.Wall)\
**Post date:** [25 August 2025 19:05 UTC](https://community.openenergymonitor.org/t/troubleshooting-flow-meter-comms-on-the-emonpi2/29035/3 "2025-08-25T19:05:36Z")

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Another topic relates to this [SSH to a new emonpi2 (Heatpump level 3) / Flow meter not detected](https://community.openenergymonitor.org/t/ssh-to-a-new-emonpi2-heatpump-level-3-flow-meter-not-detected/29032)

To clarify, according to the preceding topic, this is a Level 3 Heatpump Monitor, and not a standard emonPi2.

@rvangraan On-line support for the Heatpump Monitor is included in the purchase price; if you cannot resolve the issue, contact The Shop: **[hello@openenergymonitor.zendesk.com](mailto:hello@openenergymonitor.zendesk.com)**.

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<div class="post-metadata">

**Author:** ![rvangraan](https://community.openenergymonitor.org/letter_avatar_proxy/v4/letter/r/f4b2a3/32.png) [@rvangraan](https://community.openenergymonitor.org/u/rvangraan)\
**Post date:** [26 August 2025 12:39 UTC](https://community.openenergymonitor.org/t/troubleshooting-flow-meter-comms-on-the-emonpi2/29035/4 "2025-08-26T12:39:45Z")

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I’ve solved the problem. The cable was bad and it the emonpi detected the port after swapping the cable.