EMONCMS multiple Publish to MQTT issue

jneves · 2020-01-01T14:45:10.007Z

Hi all,

I’m trying to have multiple “Publish to MQTT”, but all of them takes the line 1 value always…

Log to Feed value 946
Publish to MQTT value 946. Correct!
Power to kWh value 3.65
Publish to MQTT value 946. WRONG! Should be 3.65
Power to kWh/D value 2.93
Publish to MQTT value 946. WRONG! Should be 2.93

Can you please help?

Thanks

Robert.Wall · 2020-01-01T15:21:49.370Z

It is doing exactly as it says. From the ‘help’ pop-up text on the Inputs page:

Power to kWh: Convert a power value in Watts to a cumulative kWh feed.

Visualisation tip: Feeds created with this input processor can be used to generate daily kWh data using the BarGraph visualisation with the delta property set to 1.
See forum thread here for an example Creating kWh per day bar graphs from Accumulating kWh

Output: Does NOT modify value passed onto next process step.

and for Power to kWh/d

Convert a power value in Watts to a feed that contains an entry for the total energy used each day (kWh/d)

Output: Does NOT modify value passed onto next process step.

The pertinent part that explains what you are seeing is “Does NOT modify value passed onto next process step.” So, you need a separate Feed to accept the kWh values. You set that when you add Power to kWh & Power to kWh/d

I’m not an emonCMS expert so I can’t help you any more.

jneves · 2020-01-01T17:18:59.279Z

That I think is what I have…

Please check the screenshot.

Screenshot 2020-01-01 18.17.192390×695 98.4 KB

Robert.Wall · 2020-01-01T20:38:20.318Z

What you have is the value (496 or 377.00) being passed down in steps 1, 2, 3, 4, 5 & 6 UNCHANGED, as it says in the help. So your ‘Publish to MQTT’ should be publishing 496 each time. And it is. Clearly, that’s not what you wanted nor what you anticipated. What you need to do (apparently), and I don’t know how but I suspect virtual feeds might be involved, is send to MQTT the value of the feeds AC-Solar:AC-SOLAR-KWH and AC-Solar:AC-SOLAR-KWHD

Sorry, but I really can’t help any more.

[Edit: See my next post for how.]

jneves · 2020-01-01T20:56:07.548Z

@Robert.Wall thanks for your prompt answer. Let’s see if someone can help, your logic seems right, but the steps to do it, I don’t know neither.

Robert.Wall · 2020-01-01T21:06:35.663Z

I tried searching for “Publish feed to MQTT” and found:

Posting from emoncms to mqtt Emoncms

The “power to kwh” process doesn’t change the power value that it passes on to the next process. To do what you want you could use “reset to zero” followed by a “+feed” and select your kWh feed from the earlier “power to kWh” and publish that to mqtt eg 1 log to feed power1 2 power to kwh energy1 3 reset to zero 4 +feed energy1 5 publish to MQTT

So now I do know. It’s a bit tortuous - at the end of your list (after step 13) you need to add the reset, +feed & publish twice (once per feed). And obviously you don’t publish the wrong values in the old steps 4 & 6 but move those down the list.
(Whether I remember the next time is a moot point.)

jneves · 2020-01-04T15:16:59.134Z

Hi @Robert.Wall

You gave me the solution.

Here is the screenshot with the input!

Thanks

Screenshot 2020-01-04 16.16.422303×605 80.1 KB