Process List, Why cant you Divide?

Emoncms
1

Hi
On the process list, why can’t you divide or take away a fixed value?
I’m trying to get an average of two temperatures but I cant because the process list doesn’t offer a basic functionality of dividing, I am assuming there is a reason? or am I being dumb?

Also
To simplify tariff rate changes, I input the rate from NodeRED and publish to MQTT, I then times that input by the daily KWh when I want to calculate the daily cost. But I’m having odd values with the final calculations like £100 of electric used that day. For the life of me I cant work out what’s going wrong.

Regards
Dave

2

Maybe not dumb, just overlooking the fact that if you want to divide by 2, simply multiply by 0.5 :wink:
For subtraction, add a negative number.

1 Like
3

Thanks Bill
I’ve been sitting her for the last two hours with a calculator trying to work that out!

Regards
Dave

4

A bit further down the pulldown list are selections for adding and subtracting inputs as well as feeds.

5

I don’t know what’s going on with the calculating of energy using an input, fo example you can see that yesterday it is saying that 0.15M3 of water is £581.97.
I think its also related to restarts as yesterday my EmonCMS crashed again.

Emon

6

Post a screen cap of your process list for that entry, so we can see what’s happening.

7

I’ve posted screenshots of the process list and the NodeRED flows…

Emon 2
Emon 22008×918 164 KB

Emon 3
Emon 31085×500 57.2 KB

Emon 4
Emon 41136×457 63.8 KB

8

Which items on your supply process list setup page are the ones that handle water usage?

9

Sorry the Water and Gas process list are as below…

Emon 5
Emon 51954×811 146 KB

Emon 6
Emon 61948×928 159 KB

10

Are the numbers correct for the “Today’s Data” calculations shown above in post #5?

11

Yes today’s data is correct.

12

One difference between the gas and water calculations is a multiplier on line two.
(I’ve never done water or gas calcs with emonCMS, so I may not be able to resolve your issue, but I’m tryin’) :grin:

13

I appreciate your help Bill.
The gas is converted into m3 and dealt with in cubic meters as you only want m3, KWh and Cost. Whereas water you can quantify it litres.

14

Gotcha.

15

The accumulator function gives an ever-increasing tally (if memory serves) but you need a tally that resets each day. I remember reading about it, but I’ll be dipped if I can remember the details.

The question has been asked before, so you might have some luck searchng the forum for accumulator and daily reset or words to that effect.

16

Thanks Bill
I’ve had a search but couldn’t come up with daily resetting that was applicable to me, I have realised thou that when restarting the EmonPi, the daily total is the grand total of the accumulator and not just today’s figure.

17

did you see this one?

The post immediately following the one at the link sounds like it may be what you’re looking for

18

Thanks Bill
I did see that but didn’t read it all the way down as I thought it was a timezone issue,
I’ve put a couple of test processors in to see if they work.

19

Yeah, I probably should have linked to this instead.