# EmonTX4 with extension board over USB?

**URL:** <https://community.openenergymonitor.org/t/emontx4-with-extension-board-over-usb/24495>\
**Category:** emonTx\
**Created:** [1 October 2023 08:45 UTC](https://community.openenergymonitor.org/t/emontx4-with-extension-board-over-usb/24495 "2023-10-01T08:45:40Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![psykok](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/psykok/32/26198_2.png) [@psykok](https://community.openenergymonitor.org/u/psykok)\
**Post date:** [1 October 2023 08:45 UTC](https://community.openenergymonitor.org/t/emontx4-with-extension-board-over-usb/24495/1 "2023-10-01T08:45:40Z")

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Hi,

I just starting some test with the 6CT extension board.  
Firmware works fine and I can see the correct value in the serial monitoring.

Unfortunately I not getting the data in omoncms.  
My board is connected over USB-C to my RPI. just wondering if that should work with the EmonLibDB firmware ?

Alex

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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:** [1 October 2023 22:13 UTC](https://community.openenergymonitor.org/t/emontx4-with-extension-board-over-usb/24495/2 "2023-10-01T22:13:41Z")

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Which sketch are you using?

As far as I can see, Trystan hasn’t published a sketch for the emonTx4 with the expansion board and the serial output in the format expected by emonHub - this format exists only in this 6-channel sketch: [https://github.com/openenergymonitor/emontx4/tree/main/firmware/EmonTxV4](https://github.com/openenergymonitor/emontx4/tree/main/firmware/EmonTxV4) (Lines 432 onwards)

I think you will need to use the ‘max’ demonstration sketch included with the emonLibDB library and change or add to the serial output whatever data you need, using the format from the 6-output sketch in the link above. Alternatively, you could start with the 6-output sketch and add power channels 7 - 12. If you do it this way, you must either turn off the radio or not add to the data sent by radio because there is a limit on the message length. I do not know if there is a length limit for the serial output into emonHub.

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**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:** [2 October 2023 05:32 UTC](https://community.openenergymonitor.org/t/emontx4-with-extension-board-over-usb/24495/3 "2023-10-02T05:32:34Z")

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> [@psykok](#):
>
> Firmware works fine and I can see the correct value in the serial monitoring.

What is the data format you are seeing?

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**Author:** ![psykok](https://community.openenergymonitor.org/user_avatar/community.openenergymonitor.org/psykok/32/26198_2.png) [@psykok](https://community.openenergymonitor.org/u/psykok)\
**Post date:** [2 October 2023 05:54 UTC](https://community.openenergymonitor.org/t/emontx4-with-extension-board-over-usb/24495/4 "2023-10-02T05:54:42Z")

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I managed to fixe the issue by following the solution describt in this topic:

> [@EmonTx4 not showing in Emoncms](https://community.openenergymonitor.org/t/emontx4-not-showing-in-emoncms/24236/16):
>
> Hello @lamixer replying here in reference to your support ticket, as I think the resolution of this might be useful for anyone else troubleshooting as well. Here’s my understanding of your setup so far: You have an emonTx4 with the 6CT extender running the EmonTx4 + EmonLibDB Continuous Monitoring Minimal Demo with rf firmware. You are trying to connect this directly via USB to a local VM running emoncms. The standard data format of this firmware is not compatible with data over seria…