Average 2 temps to drive PID

General
1

I have 2 fermentors in the same cabinet. Would it be possible to configure the PID process for the fridge to drive off the average of both fermentor temps?

2

No, at the moment it is not possible to use multiple sensors as input.

3

It would be quite simple to add though, I’ll have a look.

A block with a list of sensors and a choice between average, min and max, which can be used as a sensor itself.

4

I got started with an implementation.
The block takes a list of sensors, and combines them with mean/min/max.

Some open questions that I’d like to ask this community for feedback on:

  • When sensors are not found, they are just ignored now. Does that sound like the right way to handle it? E.g. if you have an average of 2 sensors and one is lost, the value of the sensor still remaining is used.
  • What is the best name for the functions, easiest to understand?
    • Mean/Average
    • Minimum/Lowest
    • Maximum/Highest
5

This is awesome, with my 50L fermenter, I always was wondering how much of a temperature differential between a thermowell at two depths, and if there was, this would provide a better input to the PID.

When sensors are not found, they are just ignored now. Does that sound like the right way to handle it? E.g. if you have an average of 2 sensors and one is lost, the value of the sensor still remaining is used.

I think this seems reasonable, when I was using some cheaper sensors, sometimes they would glitch out, so this could be a solution for a “backup” sensor, it at least could be a selectable mode of operation if this does not act as people want.

What is the best name for the functions, easiest to understand?

My vote:

  • Average
  • Minimum
  • Maximum

What is the use case for the CombineFunc::NONE? Any reason you wouldn’t just default to CombineFunc::MEAN? Based on the code it would just always be invalid.

6

Thanks for the feedback!

You make a very good point. In many enums of the software, I have zero as ‘unconfigured’ state. This ensures the system doesn’t act on settings that are not configured. In this case however, I think that indeed falling back to average as the default makes more sense.

1 Like
7

Just got my Spark3 yesterday, it’s awesome and really fun to play with. Gonna use it for a RIMS setup.
I would like to use the average temp from 2 temp sensors (temp out of Rims and in the middle of the mash tun). Do you have any ETA on when this feature will be added?

8

Possibly today, probably this week. The new release includes the Temp Sensor (Combined), and is ready to go live as soon as we track down some last-minute bugs.

9

Sweet, that will be fun to test.